~'HESIS

Presented in -oartial fulfilment of the requirements for the Dee:;ree of' J.Iaster of Science with Honours in Zoology.

THE E C 0 I1 0 G Y 0 F

H I C R 0 1.1 U TAci.IAl'JIAE (':; A L K E R).

By

R. J.D. Hilson "'

...... I

~L cm~Ei:rrs. 2..7 'b'-f­ Page. CHAPTER L INTRODUCTimi. ,55' !o (1,

1. Habitats.

"'• Lcwer ;:tyx fodder crop.

2. Ree.r:ing techn:i que2.

a. !:onthly feeCliEC test

·b. Re Jtic!:orrnlf:· tasma:niae

c. Pr to:cs

o.. Pa::"asi te

e.

technicp~es.

b. C.'::trifucation

6. Tr3.pping.

CHAPTER III

-1..

o,, Ir::a:::;o

c.

d. Pupa

2. Life-history.

a. II

b. Larva

c. Pupa

d. Imago

e. Overwintering

f. Feeding

c;. Distribution of Micromus tasmaniae

CHAPTER IV. DEPEP,SAL AliD POPULATIO~T FLUCTUATIONS.

~.. Populat.:Lon trena$ of e.phids and Micromus

tasmaniae.

2. Morts.li ty in naturi?.l population of :tficromus

3. Karking and releadng of adult Mioromus

4. Micromus tasmanioe

CHAPTER V.

1. Parasites.

a.

b. Eymenopterot:.s parasite No.2.

c. Hymenorterous

2. PrPdators.

a. 2rLlers

h. Psooids

c. Hemipterrm

e. !f!ites

3. Virus III

CHAPTER VI. BIOLOGICAL CO:::-TTROL OF _APHIDS. 60

1. 3iologic2.1 control

2. Outline of a. Micromus tasmaniae rearing

progre.mme.

a. Equipment

b. ;c,reeding replacement Micromus .

tasma.ni ae a.dul ts

c. Rearing Micromus tasmaniae for

largesca:J;e relAa.sing.

CEAP'l'ER VII.

Crossin5 populations

2. Veriation clue to sex, geoc;raphic location

and S83,SOn

CiiAP~E'R VIII. D::::::CUfSION 72

70, FISlJRES 2 - !1-5 i -

79

:SIDL I OGR.ilPHY

APPEHDICK I - 1lii T'!

LIST OF FIGURES.

Frontpiece 1Jicromus tasmani :::e i~maso

2. ~'ty:z- chou moellier in May 1963

3. 5ize variation in chou moellier plants

Distril,u_tion of the cahhages 'Yi thin the two plots.

5. Cablages of plot No.1 in March 1963

6. Ce.bbages of plot No.2 in December 1963 and the

thermograph shelter.

Cylindrical grease

Grolmd L:vel -::;ater trau.

Eicromus tasmaniae. Top. Anterior hel3.d Bottom. Mandi1:lcs.

i 0. H~ cromus tasmania.e heao, lateral.

11. Eicromus tasmaniae mouthparts. I1eft. Latium J<-Iaxilla

12. 1-~etathor:wic leg. Right. Prothoraeic tarsus.

and fem-'!_le

="=:...::.::=::. ~~c:::::.':':.'::::.=c~:::. wine;s. A. Forewing venation. B. Hincl:vling venation C. Jugal lobe. D. Frenulum.

15. tasmantae. 16.

17. ~-1icromus tasmaniae rmpe.. A. Unidentified nro-tru~~·er:mce J. I1a ters_l view of an ab­ dominal pap:i_lla.

18. onment 19. Micromus tasmaniae eggs. A. Sterile YJi::1ter egg at four weeks.

20. Duration of the larval st9ges in Micromus tasmaniae

h6inpariHi vri th average monthly temperatures.

21. The:-relationship of larval headwidth to l'l{ie•

22. ltoul ting second ins tar larva of Micromus

cocoon.

21; .• Duration of pupation in Micromus

25. Micromus !a~iae preima:o-inal maul t. A. Lateral aspect ..:.;. Dorsal asnect

em.ercer1ce times i11 tv.ro

Monthly cl cons tas1~1an.; a.e

larvae.

29. Incubation

i::1 sunmer and winter.

30. in the T·~ orth

Islanri.

31. Distril,utior. of :Micromus tasmaniae in the ~outh

Island.

32. Distribution of aphids in the chou moellier.

33. Distribution of hemerobiids in the chou moellier.

of hi' cromuf;. iTT '~ 36. lf:icromus te:smaniae mortality. A. Total monthly

c1e-8.ths o2Ee:c~vecL B. An11.lysis of deaths,

37. vdthin

cabbage plot 1.

38. ~e13.tionship of l~ce'.'ling numbers (attracte to

ll. u"'. r:',-'- v)\ a,nd .

39. caucht by the Lincoln College li::;ht

40. 1\~ict'omus tasmaniae fli,r:;ht t:Lmes at Lincoln College.

41. IL'lachris T:OP· Adult. ?ottom left. Eead of J "rv-c:.

_te :t!o. 2. ltdult. J't. '!en-!::::~8.1 J:, Dorsal

+)·l -, tasr:sn::LB e

( 1) Ca.G;e

(2) Lii

(3) Feeder

(lt-) Pup-<:tion tube

1ricrom'Js tp.smaniae. c > sexual and ;: ea2. onal

(Canterl·ur.r) v:;_;:>i?tion in form\ri.ng length.

represen1_:~tiorl of thP relative n1J.mbers

of stucUed. inr.ectE from Octooer to April.

~r:m Zes.land 7rheat

'l'a":~·le 2. ?~1:pat::i.o11.

observed. in the caob,1.ge

plots. VII

Tal)le l; .• List of aphid species used in the study.

Ta')le 5. The final count, number 76.

Tn~-·le 6. Hie~ .:tasmaniae markinc; and relee.sing. Tal:·le 7. Seasonal life histories ('f ----- Tal::le 8. pupae collected

in May 1963.

Table 9. Results of interpopul11tion eros

Table 10. Length of pupation by progeny of interpopulation

crosses.

Ta1·.le 11. Analysis of variance of fore-wing length in males

and femaL s in the C.<:.ntercur>J popu1 · tion (luring

spring and viin ter.

Table 12. of va.r4 a.nce in fore-wing lengths in males

and females of Ca.ntor1:ury, liawkes and

Taranaki c::in ter populations. 'f'HE Tj9RARY 1 ONIVERSITY OF CANTERBUI'tl' CHRISTCHURCH. N.Z. CHAPTER I. INTRODUCTION.

New Zealand relies upon primary produce for ninety percent of the nnational income. As our farming becomes more intensive insect pests (such as aphids and grass grubs) will cause greater losses to production. The aphids introduce viruses into the plants when they feed. The green peach aphid,

Myzus persicae, is a vector for sizty viruses including: lettuce big vein, lettuce mosaic, tomato spotted wilt, 'out it is the yellow dv.·arf virus carried by ~idosiphum padi which is causing the most serious production losses in cereals. In contrast to the d.e:>truction of crops by Pieris rapae (white butterfly) and

Persectania ave:Bsa (army worm), the symptoms of the virus may not r)e immediately obvious. Virus particles multiply in the host plants and any sap sucking insect feeding upon it may become a virus vector. The rate of aphid reproduction is determined largely by temperature and in summer a nymph may mature and re- produce five d~ys after being "born. Each individual aphid deposits not less than twenty to twenty-five progeny in each generation. If effective biological control is absent this increase is more or less unhindered and a virus may spread rapidly through a crop. 5oth alate anu apterous aphids are virus vector~i. Resistant cereal str"'ins exist but are fre- qucntly low producers, and so chemical sprays are applied to the more susceptible higher producing va,rieties. Biological control of aphiG.s hy the release of predators has not yet been attempted. 2 The following table shows how the virus (especially yellow dwarf) and weather have affected wheat production in the last three ye:::.rs. Although the acreaee sown has been increased, production has not improved due to the detrimental effects of bad weather and virus infection. In 1963-4 production wa:s: increased as weather anrl aphids were not a problem.

Year. Acreage. Bushels.

1960-61 186 '788 9,300,000

1961-6~ 186 ,288 7,800,000

1962-63 210,800 9,200,000

1963-64 203,000 9,900,000

Table 1. New Zealand wheat production and acreage from 1960-64.

This Thesis is a study of one apl:illlid predator which has possibilities as a biological control agent.

The original aim of this thesis was to study the life history of Mioromus tasmaniae, concentrating upon the morphology.

Work began in February, 1962 but ceased in May, 1962, after some preliminar'J reading and o"bservations had been made. The study I., was resumed in l.Trmuary, 1964 and experimental vmrk ceased one year later. During the latter period the theme of the thesis changed to ecology. Two areas which were studied in detail (a chou moellier fodder crop at Lo:;er 3tY'...:: a...'1d a cabbage plot in a home g~rden) introduced the author to the aphid pro1:1em of New Zealand. 7 J CHAPTER II: lVIATERIALS AND METHODS.

II. i. B:abO: tats.

Two main areas were studied during the course of this

Thesis, (a) Lower Styx fodder crop and (b) home garden cabbage plot.

(a) Lower Styx crop, Chou rnoellier, was grown on the property of

Mr. G.T. Hutcheon, Lower Styx Road, Marshl.1nds. Each year a chou crop of approximately three acres was grown to provide winter feed for a dairy herd. 1lhe seed was drilled in Novern1::er 1962.

V,'hen growth cer::.sed in May-June 1963 the plants stood between four and six feet trill. The last of the crop was harveste-d by early

Octol>er.

The soil is sandy and poorly drained. The rows of chou moellier were eighteen inches apart and individual plants were separate-d ty three to six inc·t,es, providing easy access,

(fig. 2). Growth over the pacirioclc was consistant except for two small areas, one in the midcile of the northern edge and the other in the south-west corner, where the plants were stunted.

Vegetative growth was concentrated at the tops of the plants, not rna) leaves growing from the stalk. The smallest plants -below the canopy (fig. 3) were found to contain as many

Micromus tasmaniae as the largest plants. A mat of rotting vegetation on the grou.nd provided cover for rna11y insects. In the north-east co::-ner of the pad,::ock: pine needles had a.ccumu- lated between the rows and the 1-:ahitat was unfavoural:le for heroero1~ii ds. The large pitted leaves held quantities of water and helped to keep the environment wet. 4

Along the eastern edge potatoes were planted and few

adult hemerooiids were found upon them. The many thistles which grew along the southern edge supported numerous l'h_

tasmaniae la~vae.

(b) A cabbage nlot of thirty to forty cahbages was kept 'Jetween

January 1963 and January 196~.. In this area systematic obser­ vations were made to provide details of population trends in M. tasma,nia.e. The cal,bages comprising the two plotsr were spaced as shovm in fli!gure l~-, where each circle represents a cabbage and numerals are reference nu111-::>ers.

1N11en the study was initiated, (,January, 1963) the plants were fully grown. J)y autumn (fig. 5) most of them had flowered and their vegetation deteriorated until August, Septem1;er and October when they were pulled out. In March plot two was planted alone;side plot one. The young cabbages ':;ere supporting aphids prior to the removal of the final cabbages of plot one.

The plailts grew quickly in the spring and formed hearts 1)y Feb- ruary, 1964 (fig. 6), when the study was terminated. In this way a habitat and food ;:ource was provided for M. tasmaniae for a year.

The individual plants varied in size, shape, texture and height, forming a range of ha1:i tats which influenced 1Joth aphid and hemerotiid numbers. ':!hen leaves fell from the pl~'1ts they accumulated in piles wcich provided shelter for .M. adults, larvae and pupae.

The soil is a rich black alluvium which did not dehydrate 5 or crack. Trees a'1d fences provided shelter except in winter when the area wa.s exposed to the south. Although not shaded, heavy clews, rain, and frost kept the environment wet and cold in winter.

II. 2. Rearing Techniques.

II.2a. MonthlY- Feeding test. Five newly hatched larvae were reared in ( 1 11 x 1-:l") glass tubes each month. Each aphid fed to the isolated larva was of equivalent volume to an adult

Rhopalosiphum padi. In the absence of naturally occurring aphids during winter, populations of this aphid were reared upon cereals in heated glasshouses (60 ~ 75°F). The nylon nets used in the raising of hemerobiids (see Chapt. II.2b) were util­ ized. A ryegrass-black barley mixture (eight seeds of each per pot) was found to produce maA.'imum foliage which did not readily deteriorate as aphid numbers increased. 'Jl:o counteract plant wH ting, aphids were introduced to freshly potted plants monthly and a copious supply of large aphids was thus provided continuously.

II. 2b. Rearing 1.1. tasmaniae.

Adults were kept in pint 'Agee 1 j a.rs and aquaria.

Folded filter paper or dead leaves formed the shelter. 'Shadow' nylon was used to cover the tops of the containers. A honey-water mixture was smeared over the nylon to feed the imagines, ·but aphids

(if available) were also provid.ecL. Fifty adults per jar could ·'oe kopt alive for periods up to three months in this manner.

Oviposj,tion on cotton wool occul"!red after the adults had been supplied with aphids. The eggs readily dessicatedif the 6

air in the container was too dry. The humidi~ was main-

tained at a suitable level ty moistening the cotton wool.

Petri d:ishes were the test containers in which to hatch larvae because they could easily be removed.

Larvae were raised in (4' x 1') glass tubes and petri dishes. The cork of the tube was wrapped in cello- phane and this prevented the larvae entering the gap between

cork and glass, so reducing the deaths due to squashing when

the top was removed. Filter paper in the tube provided shel-

ter (e. g. from light) and a substrate upon w.hich to maul t. It also reduced environmental pollution ·r;y absorbing excreta.

Virus epidemics occurred if larval concentrations were too high (over 30) in tubes. Residual skins of aphids (esp. Macro-

siphum rosae) if in large numbers, seemed to transmit virus in- fection so were removed regularly. Tu1)es were sterilized before reus age. In the absence of aphids the larvae readily sucked one another, l·ut normally losses were small.

Pupati.on sites were provided in the tubes 1;y folding paper to form a ga.p of l"' ss than one quarter inch between itself and the glass. An ink. spot was placed on the glas.S. overlying the pupa an.d its location and da.t&. of spinning was marked on tissue paper strips wrapped round the tube. The ink spot was removed when the imago emerged from the pupa. The length uf pupation waf.. the time between the date in the circle on the tissue paper, ar1d the date upon w'bich the dot had {)een removed. The paper inside the tube spaced the pupae and prevented clumping.

The pupae inside the turce required no ad• i tional attention. 7 M. tasmaniae were reared in thermostatically heated glass-houses (60-75°F) at Crop Research, Lincoln 1962 and at

Ilam, in those of the Botany Department of the University of

Canter~~ury, in 1963. The hemerobiids were confined by nylon nets to cereals, growing in eight inch (diameter) porous pots.

The plants were hosts to aphids upon which the lacewings fed.

11 11 The nets were made from (30 x 20 ) rectangles of 'Shadow' ny- lon. The thirty inch edge was made~-into a hem through which a twenty r)y one inch elastic length was threaded. The ends of the elastic were se1vn together as were the two twenty inch edges of the rectan~le. The elastic held the not close to the pot. A wire frame made of a five inch diameter circle of wire with three fifteen inch legs supported the net. String W§S used to close the top of the net above the frame. Exposure to sunlight made the nets brittle and elastic rotted with time cut they were very useful.

A two foot square glass cage wa.s constructed in autumn

1963 in which a forty watt light bulb was placea_ as a source of illumination and heat. Soil was placed in the cage and cereals were plante'i. It was hoped to be acle to raise large numl;ers r:t: aphi'us on the plants so lacewings could be reared. Although the thermostat kept the temperature at 65°F the lighting was insuffic­ ient and the plants were anaemic.

II. 2c. Predators. 1.~:ihen an insect was suspected of being predatory it was ca.pturec~, kept alive in the presence of M. tasmaniae and its reactions were observed. 8 II. 2d. Parasite rearing. Anachris zealandica imagines were kept in preserving jars with nyJ,on tops and were fed honey and

water. Larva hemerobiids released into the jar were para-

si tized ty the imago hymenopterans. The larval parasite

emerged from the M. tasmaniae larva twenty days after its ovi-

p6si'fi6ri. All stages cc,uld l:ce reared without difficulty in

one jar.

II. 2e. Interpopulation crossing in M. tasmaniae.

Eggs collected in May, 1963 .from Hawkes Eay, Taranaki

and Canterbury were hatched, the larvae reared and allowed to

pupate. The adults emerging from the pupae were sexed and

sorted into one of the six crosses or three controls comprising

the experiment.

The trial was initial1y undertaken in a glasshouse but all populations except the Canterr:ury control died soon

after releasing into cages. It was repeated successfully when

the insects were reared in pint 'Agee' jars.

II. 3. Staining techniques. All stages of M. tasmaniae were preserved in Anthropod fixative. (Weaver and 'l'homas. 20gms

chloral hydrate, 2.5 cos glacial acetic acid, 5.0 cos 4JJf~ for-

maldhyde, 100 cos H 0). Specimens were mounted in polyvinyl 2 alcohol (formula WA of Salmon 1952) and placed in a heated (60°F) 2 oven for four weeks. Although not a perm.a.nent mounting medium,

P.V.A. proved. satisfactory if the cover.s',lip was sealed to the

slide, 11y enamel paint.

Imagines were oiled gently in ten percent potassium

hydroxide-water solution for five to ten minutes to produce 0 / clearing. This method was especially useful in the interpre-

tation of genitalia.

Specimens were em!:,edded in wax and dissected with pins.

A Reichert binocular microscope and a eyowa (model KHS-2-6) monocular microscope were used throughout the study. Measure- ments were taken with the Kyowa fitted with a micrometer eye piece.

II.4. Marking.

Marked adult M. tasmaniae were released into the

cabbage and rhubarb plots. Numerous dyes and pa.ints were tried

on the adults before t 'tms discovered th.'lt enamel house ~paints were ideal. Licking of the paint (ancJ~ ensuing death) was pre- vented by placing the paint dot well back on the forewing.

Different colours and aptterns were UEed to distinguish between the different ba,tches released.

II. 5. Virus Isolation Methods.

The isolation of virus polyhedra was carried out cy

a) Giesma staining

and b) centrifugation.

Dead larvae, pupae and adult M. tasmaniae were ground into a fine dust. After the addition of water a brmvn, strong- smelling solution was produced.

a) i/ a drop of the above solution was dried slowly on a slide,

ii/ giesma was added to the slide

iii/ after one minute the stain was washed off hy distilled water.

iv/ staining and washing was re- 10 peated.

v/ a coverslip was placed over the stained (blue) area.

vi/ the coverslip was sealed to the slide with nail polis;h.

The slide was examined under an oil immersion micro- scope and the virus polyhedra were readily distinguishable by their resistance to stain.

b) Centrifugation. Density-gradient columns were prepared of sucrose and potassium tartrate solutions in (1 x 4.5 em) guartz centrifuge tubes. Gradients were made by layering success- ively in the tubes .3 mls of sucrose solutions containing 400, 300,

200, 100 and 0 gms of sucrose per litre of distilled water. The potassium tartrate columns consisted of layered . 3 ml solutions containing 600, 500, 400, 200 and 100 gms of potassium tartrate per litre of distilled water. The columns were kept at room temperature for two hours to allovr the la;rers to settle. The ground insect solution was diluted to 1/3rd, 1/6th and 1/60th of its original concentration and .1 ml of each solution was layered on separate columns. The tubes were spun in the u:j tracentrifuge

(Spinco model L) at 12,000 revolutions per minute for ten minutes at 40 C. After removal.. from tbe Spinco the tubes :ere placed under a fifteen watt low pressure mercury vapour lamp which passed an ultraviolet beam t> rough their contents. Particle layering was evident in the 1/3rd and 1/6th dilution gradient columns and four particle zones were vd thdrawn from each tulJe ty sterile Jiypo,iermic syringes. 11 Each isolated zone was poured into 3 x J inch glass

tubes and spun in a :)erval centrifuge for fifteen m~inutes a.t

12 ,GOO revs. per minute. In each of the solutions particle

aoourn.1~clation resulted in the formation of a pellet on the bottom

of tm tblbe. Pellet smears were placed on slictes and giesma

staining carried out.

In all phases of virus isoh.tion sterilized equipment was used and care was taken to prevent virus contamination from benches, floors etc.

II.6. Trapping.

In the chou rnoellier observations were made whi:te

moving slowly amongst the plants. Transections as a method for calculating insect numbers are ideal for small brassica and fodder crops but were not found satisfactory here as the pla.Dts were too tall.

In the chou moellier variouz types of traps were used: a) cylindric:,1l grease trap (fig. 7) consieting of a tin cylinder

six inches in diameter whj_ch was fixed on to a six foot long

stake. The tin was painted yellow as this colour has been

shoV¥'11 to be the colour most attractive to aphids (A. D. Lovre

Pers. Comm.}. A strip of plastic was wre.ppecl rou!1d the cyl- inder and its ends pinned against the tin -oy a piece of wire.

A clear car grease (Shell Compound Grease 0) was smeared over the surface of the plastic with a stick. The grease was later

off the plastic and dronued i.nto 70;1~ aJ_cohol to free the - ~- insects. _1\l though traps were effective in all types of weather 12 they needed clearing weekly, which was not possible. Four traps were placed round the perimeter of the crop.

b) G-round level grease traps were made for usage in- side the crop. Flattened rectangles of plastic were pinned to

( 12" x 16") pieces of wood and covered in grease. The trap was pushed into the soil to just below the level of its surroundings.

Protection from the weather was provided by a cover made of hard­ board (20" x 15"), supported by six (8") legs.

c) rrwo ground level water traps (fig. 8) were used in

11 the fodder crop. A tray of galvanised iron (20" x 12" x 2 ), painted yellow, was ple.ced in the soil. The tray was filled with water and detergent. A e;rill at one end prevented the tray from overflowing. The surface tension of the water was decreased by the soap and captured insects were unable to escape. Large hardboard covers were ma.de to protect these t-raps as can be seen in the photograph.

An assortment of nets and beating trays were used.

Insects were caught individually in a..n aspirator.

Aphids were always collected with the hemerobiids ao that canni- balism could be prevented. No praotic

The author endeavoured to count the total M. tasmaniae population within the cal1bage plots by inspPcting all the cabbages.

Thr counting enta~Lled careful unfolding of all 1i ve vegetation, an inspection and replacement. All o·c:tr::.ed veeetation (e. g.

1eaf corners) was unrolled, checked for lacewings, then re-rolled.

All hemerobiicts on a plant were C<'Unted and their sex (if possible), 13 colour, activity, type of death and proximity to food was noteo..

Leaves which had cietached themselves from the plant were checked in the same manner.

For the first two months of the study inspections were made at two-day intervals, but after this, once every fourth day.

As the cabbages r)ecame better knovm bias may have occurred, so the counts were made from different ste_rting points.

A thermograph was recording in the garden for forty three weeks of the year.

In the homegarden four lights (40 and 60 watt) were left

on between dusk and midnight. The area in the vicinity of each of the bul1)s v1as cleared at hourly intervals 1'y the author who collected the hemerobiids alive. The adult l

This trapping started in November, 1963 and ceased in Mnrch, 1964.

At Lincoln College a 60 watt our::: vms useCJ_ to attract all insects flying at night throughout the year. The light was situated in an orchard and was switched on 'between 6 pm and 2 am.

Insects attracted to the li,o;ht were killed by ethyl acetate fumes which were emitted from impregnated plaster in a tray beneath the bulb.

A suction trap built at Lincoln College provided infor- mation ar.>out M. tasmaniae flic·ht times. A steel frame supports a fan, a1Jout five feet above the ground, into which insects are dravm. They pass dovm a gauze funnel anri at the base are caught 14 upon greased discs which changed every one ~~d a half hours.

The specimens were removed from the .c,:;rease when the latter was soaked in alcohol.

Two sets of dusk observations were made in the home- gqrden by sitting ano. watching the lacewings. All movements and activities were recorded until darkness prevented accurate observation.

Carbon dioxide was used to anaesthetize all the in­ sects captured during this study and was used extensively for the handling of individual specimens. 15

CHAPTER III. LIFE HISTORY AJIID MORPHOLOGY OF MICRO:M:US TASMANIAE.

1Nalker (1860) was first to describe Hemerobius tasmaniae. McLachlan (1869) and Hutton (1899) placed it in the genus Micromus. Kimmins ( 1941) placed into the genus Eumicromus and then (1958) moved it to the genus

Nesomicromus. 'Tjeder ( 1961) synomynisecl this generic com- plex under the name Micromus, so the present species should

There is a paucity of literature a1)out the order

Neuroptera. and the author used Killington ( 1936) and Tj eder

(1961) as the main sources of information. Most papers deal with the systematics of the order and little ecological infor- mation is given. The morphological nomenclature varies consider-

{l.bly and the author followed the systems of T_jeder and Killington.

III.1. Morphology.

a. Imago. 'l'he adult (fig.1) is a small brown insect

(~ to 1 em.). A pair of long antennae are projected forward from the'head. The compound eyes are large ana. dark. The large wings form a canopy over the abdomen. Delicate, slender

protrude under the wings. tasmaniae viewed dor- sally is very narrow.

i/Head. At rest the head is held with the fe_ce in- clined steeply downwards (in Drepanacra 1:·inoc~ula the head is pulled into the wings). AnterioraJ.ly (fig. 9) the hee.d a.ppears triangular, ]'rom a lateral (fis.1 0) aspect the head is flattened and wedgeshaped, tapering f:rom the anmennae be,se, to the mand.i.- bular apex.

The epicranium is large and dorsally convex. It

is demarcated laterCJlly from the post-ocular lol,es ty the

temporal sutures; anteriorally by a V-shaped suture separ-

ating it from the frons.

The frons forms the centra.l portion of the face.

Only its dorsa.l and ventral toundaries are obvious. The

frons is separated from the ::;ena ty the frontal sutures and

from the clypeus 1w the clypefrontal suture.

The mandibles are la.rge and chi tinized, triangular

in shape, with sharp in-curved points at the apex. E€Lch has

a hollowed ventral surface, a tooth on the inner margin and a

prominent articulatory condyle.

In the labium a medial square lingula is separa.ted

from the submentum ty a sulcus. Anterior to the sulci on

the mentum is the .iunction of the labial palps. The ualus .>. ~

consist of three stout segments and both palps are used in

holding food against the mandibles. The submentum is trian-

gular and ends high up on the ventral surface of the head.

_!1_ p·1.ir of five-segmented maxillary palps lie ventral

to the labium(fig.11). In the median portion the cardo is

divided into two segments, the lJasio - and distocardo. The

tria.nE,ula.r stipes 1-·ears the pa.lifer which supports the ma}::illary

palp. The basal palp segment is rounded and -oroad, :the second

to the fourth are elongate cut the fift.h, the longest, is fusi- form. The basigalea, galea, and lacinia comprise the base of 17 the maxilla. The basigalea permits ~lexure o~ the oval galea

and square lacinia.

The two membraneous pits lying between the eyes each

contain a small pedicel segment which precedes the large rounded

b.asal segment, the scape. This is f'ollowed by the segments com-

prising the antenna which is equal to one half the total length

of the body of the imago.

The compound eyes are large a.nd hemispherical. They

appear dark in colour, but in different lights they may look

brown or green. The foramen orbitale is small.

ii/ Legs. A pair of legs are borne on each of the

pro-, mesa- and metathoracic segments (fig.12). The last pair

is the longest and largest. The coxa tapers to the trochanter.

The femora are long, flattened laterally and narrow proximally.

The tibia is the largest segment in the leg and in the hind legs is responsible for their greater length. All tibiae carry apical spines upon their distal extremities, one on each of the prothoracic limbs and tv1o on each leg of the hind pairs of legs. Each tarsus consists of five segments, the final one bearing claws, apical bristles, and an empodium.

iii/ Abdomen. In M. tasmaniae the abdomen is held horizontally whereas in Boriomya maorica it is always curved.

The abdomen comprises ten segments, the first eight of which bear spirLwles. The sternites and tergites are heavily chi tinized. Anatomical differences exist in the genitalia and associated structures of the final two female and final three male abdominal segments. 18 a) Male genitalia. Dorsally the ninth tergite is divided into a pa:i:r of ectoprocts which form the walls about the genitalia. Each ectoproct has a small ventral protruber­ anoe, the catroprocessus, and a trichooothrium. Ventrally the ninth sterni te is undivided, elongate, and protrudes pesteriorally from the abdomen as the suogenital plate (useful for sexing in­ dividuals). The copulatory organ (arcessus) arises medially on the eighth segment. This is a large, chitinized structure curving to the tapered tip. The base of the arcessus broadens to the gonarcus. Beneath the arcessus lies a pair of parameres

·which come to a common junction anteriorally but are divergent posteriorally.

Externally, the whole region is covered in setae,

(fig.13) the longer ones, at the base of· the ectroproct, close the gap between the last tergite and sternite.

b) The small tenth sternite gives the end of the abdomen a rounded appearance. Spira.cles, setae and trichobothrium are present (fig.13). The ninth tergite is divided down the midline. The spermathecae are very small and weak.

M:. tasmaniae has two pairs of membraneous wings of different size out similar form. The wings are held steeply, roof-like over the body. The inner wing margins meet over the dorsum of the abdomen vrhile the outer margins al­ most touch the substratum upon which the insect stands. The wings are distinct from those of B. maorica which are oval and 19 The cross venation is less numerous in the hindwings than in the forewings (fig.14). A convex: jugal l{lbe, on the forewing is covered in short, stout setae. A triangular humeral 16be is opposite the jugal 16be on the hindwing, and bears several long frenular bristles.

'Microtrichia cover the whole surface of the wings but macrotrichia lie only on the veins and at their tips. At the distal extremities of the veins and veinlets, there are numerous small clumps of macrotrichia which give the wing margin a spotted appearance.

The forevring is coloured light -orown with two darker bands of brown running transversely across the midccle. The hindwings are transparent and irridescent.

v/ Sexual dimorphism. The length of the fore-wing, from the thoracic joint to the lYing extremity, was measured.

Using statistical methods (Chapter VIII.2) it was shown that sexual dimorphism is significant, and that M. tasmaniae females are 1)ig.~er than males in 'both summer and winter. Figure 15 shows the size difference of the sexes.

b.~ The egg is 0.72 mms. long, o1,long, rounded at both ends, &~d bears a micropyle. The test is smooth, slightly transparent:-, off white in colour and reflects light.

c. Larva. Apart from the size the third instar larva resembles the second instar. It is fusiform in shape, being wi:iest in the region of the metathorax and the first abdominal sesment and tapering gradually towards the head and anal extremi~J. It is somewhat dorso-ventrally flattened. 20 They are active and run swiftly with a side to side motion of

the head. The tenth segment is used as an anal 'foot' except

when the larva is running rapidly, and is used when climbing

and as a hold when feeding.

The first instar larva is small (1.8 mms) and has a

large triru1~ular head (the broadest region of the bo~), numerous long setae, long legs and empodiae. It is ccloured. white with

brm•m spots. The second and third instar larvae have rela-

tively smaller heads, more setae, shorter legs and shorter

empodiae.

The third instar larva.

i/ Head. The head bears two pincer-like jaws (fig.16).

The mandibles and maxillae have tecome fused to form the siphon­

ing e.pparatus by ·which the larva obtains all its food. The heavily chitinized head supports the labial end ma."'

The ora~ cavity is not open to the exterior. The head is roughly triangular. The eyes consist of four to six ommatidia.

ii/ Thorax. This is made up of three we~kly defined leg bearing segments. The prothoracic segment is subdivided into an anterior coll&,r, bulbous central portion (bearing the legs) and a posterior band-like part. The mesothorax can also be subdivided but not the metathorax. Sclerites are conspic- uous only on the first segment.

iii/ Legs. The legs are of similer shape but the final pair are longest. The coxae are widely separated (in contrast to the adult condition). The coxa is broad and articulates with the chitinized coxal process on the central 21 thoracic surface. The coxa is attached to the trochanter.

The femur and tibia are long and broad. An empodium and set

of two claws is present at the end of each leg.

iv/ Abdomen. This consists of ten segments of

which the first, ninth and tenth are poorly defined. Each

of segments one to eight, oears a pair of spiracles. The

ninth segment is elongated with a large dorsal plate. The

tenth segment has two dorsal ulates and acts as an anal 'foot',

using a pair of eversible processes to anchor the larva to the

substratum.

d. Pupa. The exarate pupa lies in the cocoon with

the head under the thorax. The head liears two compound eyes

and a set of powerful mandibles (fig.17). The palps form in

the ventral midline.

The thorax consists of three segments, the first of

which t)ears a pair of large spiracles on prominances. The

wings cover most of the central ~ortion of the pupa. The legs

are folded tightly against the body.

The curved abdomen forms the bulk of the pupa. Each

segment bears spiracles. A small protuberance attached to

segment nine remains uniQentified (fig.17A).

The pupa is covered in sensitive setae, wtich when

touched cause the pupa, to twitch violently. Continued stimu-

lation leads to rapid opening and closing of the jaws. The

pigmented eyes are photo-sensitive and sudden exposure to light causes the pupa to tvrist violently.

The white pu~a passes through shades of brown and 22 eventually, upon maturity, the eyes, jaws, wing cases and

head are almost black.

Abdominal segments three and four carry two papillae

in the mid-dorsal line, each of which bears one set of hooks

pointing anteriorally and another set pointing posteriorally

(fig.17B). Al tho'Jgh the hooks are wi thcl.ravm when touched,

it is not possible for the pupa to withdraw them completely.

Killington (1939) suggests that they may function in anchoring

the pupa vr.i thin the cell. Alternatively, ~iii thycombe ( 1923)

suggests that they may aid escape from the cocoon. The

author cannot agree vri th the first hypothesis lJecause there

is no need. for the pupa to be stationary within the cell as

it is already in a protected site and there is no evidence of

the hooks holding the pupa in the cell. V!i thycombe 1 s proposal

appears more valid but it is difficult to picture how anterior

facing hooks could be used during emergence.

III. 2. Life History.

a.~

i. Embryology. The first changes are observed at

72 hours (fi~.18) when the contents become a creamy yellow

colour and the micropyle a brilliant white. At each of the

anterior lateral margins eye rudiments appear. There is a

slight browning of the egg in the posterior-dorsal area.

After 96 hours, general darkening has occurred.

The eyespots are more conspicuous. Four light brown bands form posteriorally. These are rudiments of the abdomen which is curved over the dorsal surface of the thorax. 23 At 120 hours the egg is darker. The eyes each con-

sist of four well defined ommatidia.

At 141;. hours the conspicuous abdomen has contracted..

The micropyle has shrunk. The dorsal surface of the chorion

forms a series of longitudinal lines.

At 168 hours an anterior indentation in the test

appears and the eyes more posteriorally. The dark abdomen

is small. At the junction of the lines in the chorion the

egg burster can be seen. This is a median, longitudinally

placed, chi tinized ridge which is V shaped, the apex of which

is cutting edge. The eyes are two black masses.

• Emergence of the larva from the egg.

Abdominal movements are the first indicn.tions of

emer,::;ence. The combined action of body movements and in-

creased blood pressure distends the larval mouthparts and

leads to the projection of the anterior tip of the egg curster

thro'..!gh the chorion just below the micropyle. The ba.se of

the lmrster produces a slit as the egg tooth moves posterior-

ally. The front region is forced forward. The head end prothorax protrude through the slit. The la.rval mouthparts

are held by the emli:r-

and the larva twists to reach the substratum and moves away.

The embryonic moult is left in the egg shell. The 24- egg burster remains attached to this moult and is seen pro­

,iecting through the slit in the egg.

Eggs will survive frosts but not long periods of freezing temperatures. The eggs are prone to dessication under experimental conditions but this is unlikely to occur in natural habitats. Figure 29 shows the time taken for winter and summer eggs to hatch. Eggs laid in v'rinter took longer to develop and 35~~ failed to hatch. In summer only

27.~ of the eggs did not hatch. Figure 19B is a winter egg four weel

b. Larva. M. tasmaniae larvae undergo two ecdyses.

The period spent as any one in star is affected by season, (Fig.

20). These larvae were raised in identical environments but as the temperatures decreased, there was a corresponding length­ ening of the period spent as a larva. Hea.d vridths of larval populations of knmm age were measured (Fig. 21) and the meas­ urements fell into three groups which probtJ,bly indicates the three instars.

The larvae select sites upon which to moult (dead leaves at the base of the plants) and they are never exposed.

The larva stops feeding and the eyes migrate alightly poster­ ior/0!1ly within the head. The anal papilla exudes a secretion which sticks the abdomen tip to the substratum. Violent jerk- ing of the head and bo~ occurs. A series of waves pass along the abdomen from posterior to anterior, initiating the shedding o:f the cuticle. Thoracic expansion causes the integument

to split down the midline., and along the epicrania.l and frontal sutures. The thorax and ventrally bent head emerges

through this slit. The thoracic appeno.e.ges are wi thdrewn,

the limbs .are moved ana. the larva twists· to the substrate

and leaves the moult.

Normally, shedding of the skin takes two to five minutes, but if the larva cannot free its mouthparts (as is

common) it may take longer. Death may occur if the larva

cannot free itself. Many moulting larvae undergo ~cdysis while hanging upside down (Fig.22).

1.'lhen touched a larva moves away or else raises its abdomen ancl ejects a drop of brown waste from the anus. Small drops of this fluid excreta are passed during larval develop- ment. The third instar larva secretes a sticky anal fluid indicating that silk is being produced.

The larva has a black head, yellow thorax and abdo- men with two longiturlinal brown stripes. M. tasmaniae larvae are distinct from ~ maorica larvae which are more bulbous and coloured da,rk brown. r ~. Metamorphosis from larva to pupa occurs within a white cocoon of sllk. Coverage is provided by a wide range of materials, most commonly rotting leaves, plant axils and under clods of earth. Usually the cocoons are found singly but for~J-four were seen on one dried-up lea£.

Once the site is selected the larva uses extension 26 of posterior segments (rather than whole body movements) to reach the points at which to attach silk. It first spins an outer loose canopy, the~ produces a tightly spun en­ circling inner envelope (Fig.23).

The process of spinning takes two to ten hours depending upon site and temper<:e.ture. At lower temper&tures

(e.g. ·winter) the larvae frequently do not spin a complete silk cocoon. The amount of silk incorporated appears to be correlated vri th the condition of the larva at the tim~ of spinning (unfed larvae tend to spin only a loose canopy while well fed ones seem able to spin dense cocoons).

Once the cocoon is completed the larva is called prepupa. The head, abdomen, legs and mouthparts are drawn in ventrally. After four days the prepupa changes and the eyespots and mouthparts can be seen in new positions beneath the larval cuticle. The head breaks through the integument and by slight body movements the pupa slowly frees itself.

The skin is slid off posterinrally and is left in the base of the cell.

If removed from the cell the prepupa is unable to walk or to spin another cocoon. The time spent in this stage varies with the season (five days in summer and thirty days in winter).

c. Pupa. The time spent in the cocoon varies with season (Fig.24). A complete result of the pupation times for the year :Ls e;iven in table 2 where the average time taken for each sex to pupate is shown. Except for May there was no 27 Ereat difference in the time taken by each sex to pupate.

During winter the pupae have a reddish tinge which is not present at other times of the year.

FEMALE TOT.AL 'Month MALE l'fumber Average Number Average Number Average -- Feb. 121 14-. 6 Mar. 68 18.3 Apr 28 32.4- May 14- 55.5 12 4-5.4- 26 50.8 Jun. 6 72.3 3 69 9 71.1 Jul. 21 60.9 33 61.5 54 61.3 Aug. 8 4-8.25 5 4-3.2 13 4-6.3 Sept. 6 28.6 5 29.0 11 28.8 Oct. 67 21.23 69 21.64- 136 21.45 18.98 Nov. 34 I 18.82 42 19.11+ 76 I Dec. 19 15.6 27 15.8 46 15.72 Jan. 9 14 6 13.8 15 13.92

Days.

Table 2. Micromus tasmaniae pupation. Average time taken for each sex to pupate in each month.

i. Emergence. The preimago chews its way out of the cocoon and selects a site upon which to moult. The head and neck stretched slowly forward and back, up and dmm. The al)domen is raised and lmrered as a series of waves of expansion

(which separates the new from the old cuticle) pass from pos- terior to thoracic ends. At no stage does the abdomen have contact ~ith the substratum. The head continues to move up

and down. The posterior pair pf are raised, extended

fully and lie alongside the abdomen.

As the thorax rises, the old cuticle splits mid­

dorsally along the prothorax, to the head and to the meso-

thorax. The jaws open and close rapidly. The head moves

back 1 through the slit but is bent ventrally. As the

antennae are wi thdra'tm the head moves dorsally. The freed

legs are activated, the body tvrists and the imaco twists to

the substrate and walk away from the pupal moult (Fig. ) •

The folded wings are moved into a vertical position

(so that their inr1er margins almost tou~h) a...'ld uncurl slowly.

Once expcmde d, the wings drop in to their normal position over

the abdomen. The colour pattern is complete i'rithin 24 hours.

r'hile the wings are elevated the anal appendages are

conspicuous. A black pellet of waste is visible inside the

abdomen. After secretion of the pellet the abdomen is lowered

and the genitalia assume their natural position.

The process of emergence t~kes five to seven minutes

~t 66°F. but at lower temperatures the adults cannot alw~ys free themselves from the old skin.

The times of emergence for winter ru1d spring popu­ lations (Fig, 26), shows there are tvro peaks of activity (dawn

and dusk). The latter population showed a vrider range of ac-

tivi ty. There was no emergence be~7een 10 pm and 4 am.

d. Imago.

i. Mating takes place throughout the year except in 29 mid-winter. It occurs mainly at night, but many Qay observat-

ions vrere made. If environmental conditions are sui table (food,

temperature) imagines mate two to three days after emergence from

the cocoon.

The male lacewing approaches the female, who remains

stationary if re~ponsive. The male walks around the female a

number of times, gradually moves close and begins to touch her

antennae with his ovm antennae. The female does not move.

Continually touching her antennae the male moves as close to

the famale as possible. The male twists his abdomen at right­

angles under the female 1 s l'rings and re-peatedly touches her a1)domen

with his own. Contact is made and the two individuals are united.

The male moves his anterior in an arc, and in so doing comes to lie under her wings with only hishead and thorax visible. To

accommodate the male in this position the female arches her

abdomen. The tvro may remain up to an hour in this position.

Frequently the female walks about with sufficient speed as to prevent the male being able to walk backi'Tards so he lifts his legs off the substrate and is carried.

The presence of a copulating pair is sufficient to attract other individuals and up to four adcii tional males have been seen lying beside females.

In the cabbage plot mating of ~ tasmaniae was ob­ served for six months of the year and 75 unions were counted.

This table gives the results. 30

Month Unmarked adults Marked adults ~otal Mating Mating Matings

Feb. 9 2 11 Mar. 1 1 2 July - 1 1 Nov. 1 - 1 Dec. 15 4 19 Jan. 40 1 41

Total 66 9 75 ·- Table 3. Micromus tasmaniae matings observed in the cabbage plots.

Of this total 27 occurred upon fallen vegetation. 59 matings involved two insects and in the remaining one to three additional imagines were present with the mat:i_ng pair.

ii. Oviposition. Eggs are laid in selected places during the third to fourth day after copulation, close to aphids, in shade, upon epidermal hairs, and in spider webs.

Captured females readily laid eggs during the first two days of captivity. Although egg laying ceases after two days on arti- ficial food, it can be restored by the introduction of aphids.

Adults raised experimentally will mate in captivity but egg production is not high (20 to 50 as compared with 50 to 100 laid by wild females).

Oviposition occurs between midnight and davm. The eggs are usually laid singly. They are glued to the substrate by an adhesive fluid exuded during oviposition.

iii. Life expectancy. Marked imazines released 31 into the experimental plots survived for 52 d~s. M. tasmaniae adults were kept alive up to 117 days in cages (in absence of predators). A total of 149 days has been recorded as the life span of one female. There are six to seven generations of M. tasmaniae per annum in Canterbury.

e. Overwintering. As stated earlier winter eggs, larvae and pupae tru

The author marked large dry cabba,ge leaves bearing pupae and placed them among the cabbages and they were 1)1o·m1 a distance of up to six feet in three days., proving that vTind is capable of dispersing leaves. No stages of M. tasmaniae were found in the soil round the cabbages when they were removed.,

'!then the chou moellier was fed off, the mat of detritus between the rows was exposed to the wind which dispersed the dry leaves about the farm. Some 1eaves removed from the hedges con- tained pupae.

In conclusion, the pupae overwintering on the leaves and in the soil provide the nucleus for next seasons population, but eggs, larvae and imagines may also survive the winter.

f. Feeding. The author endeavoured to discover the types of insects consumed, feeding req_u:\.rements, influence of season upon feeding, and the reactions of host and prey on one another.

This hemerobiid feeds on Psyllidae, Psocoptera, eggs 32 of Diptera, Coleoptera and Lepidoptera) small dipterous larvae,

(d.g. Syrphidae) and probably some small adult lepidopterans, hut in all cases only upon small, soft-bodied insects. The

Aphididae make up the greatest percentage of the food ea.ten, and so most experiments used them as the food source.

Aphid. Host plant.

Aulacorthus ~lani (Kl tb) Potato Lettuce Ovatus menthae (\Hk) Mint Macrosiphoniella s

~· Economically important.

Table. 4. List of aphid species· used in the study.

This is a list of the aphids used in the study and the plants upon which they were found. Other species were probably used, 33

tut due to the difficulty of differentiating between species,

except by close examination, it was possible for them to remain unidentified.

The larva uses its pincer-like jaws to penetrate the prey, whose body fluid.S;'are siphoned out. The antenna,e are held upwards and backwards, almost at right a..n.gles to the head. The palpi are directed down and out of the way.

Figure 27 shows how the larva holds the prey in the air, not permitting it any contact with the substratum. V1hen the jaws puncture into the integument of the prey the larva starta to withdraw the fluids. The maxillae moYe backwards and foiYWards against the mandibles. The pha~JUX is opened and closed, pro­ duod.ng suction.

The la.rva usu.9lly impl:a.nts its jaws into the soft aodomen of the prey but may attach elsewhere depending upon the angle at which it meets the e.phid. The pigmented fluids can be watched passing through the head into the oesophagus, where they accumulate. The aphids are not killed immediately and continue to struggle until exhausted of their contents.

The skin is cast aside. After e~ch meal the larva cleans its mouthparts by scraping them along the ground. ·while feeding, the larva uses its anal papilla as an anchor.

Most feeding takes place during the day. Larvae stop feeding prior to eopysis, or when starved, larvae become ve~J agitated in the presence of ~hids. They rush erratic- ally about pushing their ,jaws into every object they meet, in- eluding sucked aphid skins. Frequently these larvae 'bloat' 34 themselves by consumj_ng too many aphids, until they are too heavy to walk easily. Iim this stal~Je they cannot escape the attacks of parasites.

A first instar larva can suck a M.acrosiphUlll; rosae dry in three hours but a thir

10 and 15 minutes. Larvae reac1ily eat lh tasmaniae, eggs, one- another a..nd pupae.. A starved larva was conscious of the pres·ence of an aphid on the other side of filter paper but:)could not find it.

Figure 28 shows resUlts obtained in monthly feeding tests. Each month five newly hatched larvae were isolated and supplied with mature aphids, (usually Myzu~ persicae, and

Rhop~osiphum ~adi) until they pupated. The graph shows how many aphi(ls each individual, ate during its larvl\tl life.,

Winter feeding behaviour in 1'1i. tasmaniae accounts for , the anomalies; shown in this grapho When the temperatures de- crea,se the larvae become 'increasingly inactive and less e.ggre·ssive.

It took 35 days for June larvae to eat an average of 58 aphids i.e.

1.4 aphids/day, and 9 days for December larvae to eat an average of 19 aphids i.e. 2.11 aphids/day.

Natural food supplies decrease winter so there is greater expenditure of energy to get an equal number of aphids.

However, during winter the experimental larvae allowed aphids to vralk over them ana: amongs:t them; the larvae reacted to their presence only when ready to feeo.o It was at this time that high numbers of aphids died naturally, producing the peak on the lowest line of the graph. 35

The effect of feeding upon the size of the imago of

M. tasmaniae was also discussed in Chapter III under Sexual

Dimorphism. 1i·finter populations contain many small ap.ul ts. By

starving two populations of 1arvae it was hoped to produce smaJ.l

adults. One group produced very small adults, while the other

produced normal adults, sug.:sesting tha.t food is not the only

factor 1imi ting imago size.

a) Prey Reaction. Aphids may be able to elude a

partly aggressive la.rva by walking quickly away, but they cannot

stop a starved one in this manner. lvfature aphids repel larvae,

by kicking at them, except for the largest third instars.

Many aphids, such as brassicae, live in ve~J large

colonies which seem to provide some kind of protection from pre-

dation. ~ilhere aphids are more widesprea

wheat, the lacewing larvae and adults have no difficulty moving

amant?; them. Ini.ividue.l wandering aphids make un most of their

food.•

B. brassioae :i.s covered with a. dusting of whitish

mealy powder. This dust is produced ty wax-secr":lting glands

on the dorsal surface of the abdomen. The wa:·r. fouls the jaws

of the larvae to such a degree that feeding m9.y be prevented.

In a mixed c~lture of li.persicae and B. brassicae larvae learn

to differentiate between them, and :i_t is almost certainly the p::·esence of ;mx which causes them to react in this way.

Honeydew is excreted ·:Jy the aphid.s through the a...rms.

1!. rosae is a large aphid vli th two long ahdominal cornicles from 36 which a yellowish mass is sometimes secreted. \'Then attacked, the yellowish sticky mass ( cornicular secretion and honeydew) may be secreted over the predator. The mass settles and solidifies on the head,may impede feed:'.ng anri death 1JY star- vation occurs (e.g. a third instar Boriomya~ic~. It is

:r;)Ossible for small larvae to get caught in these secretions and to starve, cemented to the cornicle. This danger affects predators attacking the larger species of aphid and does not appear to occur vii th smaller species. The mouthparts of the imagines are such that this difficulty does not arise and all species of aphid may be eaten. No aphiris were seen to escape starved imagines.

b. Selectivity. The larvae M. tasmaniae exhibits powers of selection. All larvae eat late nymphs and seem unattracted to small nymphs. Adult aphids are not sought as they readily kick and their integuments are difficult to pene- trate. Very few, if any, alate aphids are eaten, when apterous forms are available.

Small larvae show preference for medium-sized nymphs but occasionally feed on larger aphids vrho are able to drag them around.

The plant which supplies sap to the aphid gives it a characteristic taste (in the experience of the author). £h. padi collected from clover was not eaten, cut this species when raised on ceregls was readily eaten. M. sanborni is eaten but not readily. ~ brassicae is tNcen only if no other species is provided. M. rosae is eaten, but as with the former species the 37

population becomes unhealthy, and virus outcreru~s may occur.

ii. The jaws are used for biting and chew-

and the entire bo~ of the prey is devoured. Adults readily

feed upon honey and water but aphids are their natural food source.

(They consume 1 to 4 per day). A long cleaning of mouthparts

precedes each feeding. Imagines actively search for aphids

(especially at dusk) and will fly to the largest colonies. Eggs

are ah:ays l:dcl l?hen aphids are close by.

g) Distribution of M. tasmaniae.

Collections were borrowed from the Auckland Institute

and Museum; Plant Diseases (D.S. I.R.) Auckland; Dominion Museum

anrl the Ca;tterbury .Museum. Locations from which the above speci- mens were caught supplemented the author's collection~ and figs.

30 and 31 were produced to show the distribution of the species

New Zealand.

The species is found throughout much of ~Tevr Zealand.

Six specimens were ctlllected at 3000 feet and one at 4000 feet

the Cass region of the Southern Alps, incl.icating an al ti tud­ inal range from sea level to 4000 feet.

The species was also collected outside New Zealand on the Kermedec Islands, Chatham Islands, Auckland Islands and at Edgerol in Australia (Northern New South Wales<). The species vms originally described from specimens caught in Tasmania. CHAPTER IT. DISPERSAL AND POPULATION FLUCTUATIONS.

1. Population trends of aphids and 1h. tasmaniae.

It was necessary to study the aphid population in the

chou moellier to comprehend the relationship between this insect

and M. tasmaniae.

The aphids (Myzus uersicae, Brevico~rne brassicae) first reached the crop in the south-west co!'ner late in Janua!'"IJ, at which

time the plants were between one and two feet tall. Earlier aphid flights had not become established as the landowner was irrigating

the crop vd th a large spray unit, which washed them off the plants.

Irrigation vras discontinued in early February and aphids were well established by the middle of this month. (Figure diagramatically represents the aphid concentrations observed).. In February some additional populations settled in the crop. By March, aphid numbers along the northern face were high and they were spreading to the east edge of the chou moellier. In April aphids were dis- tributed over the entire crop with highest numbers present along the north and east sides. There was a very marked decline in

May and only two concentrations remained. Few aphids vrere present in June and none in July. During the five months of aphid infest- ation the main body of the population moved from the south west to the south east corner of the paddock via the northern side.

The areas of the crop: inhabited by Anachris zealandica and Micromus tasmaniae are represented in figure 33 by symbols.

The insect density is shown by concentration of the symbols .•

Lacewing adults were found in large numbers from January onvrards, 39 being most common in March and April, ai'ter which their numbers declined. The imagines were the easiest lacewing sta,ge to find, being found upon most hanging dead leaves. Large numbers were seen mating (up to three pairs on one lea£). No mating was ob- served after April. Captured females readily laid eggs on their first night of captivity.

Pupae were difficult to find early in 1963 out large latches 'llere found in autumn on dead hanging leaves, on rotting dead lee.ves on the ground, and round the base of the stall<:. Up to twenty pupae were sometimes found on one leei'. In :May, pupae were common ·hut a creat numoer were dead.

Larvae ·were found upon most parts of the plant, usually close to the e.phid colonies. Most specimens found were station- ar-J and feeding. Larva vrere found singly but occasionally large groups of smc:.ll larva vrere observed.

Boriomya maorica and Drepanacra binocula imagines were c~.ught in small numbers during March and April (Fig. 33).

M. tasmaniae concentra-tions moved from the south-west face of the chou moellier to the south-east face by IYay of the northern face. Appendix- 4 gives the numbers of individue.ls t~~en from this locality during 1963.

In the cabbage plot, aphid movements were again studied.

In Januar.J, the greatest concentration in plot No.1 was found upon the cabbages along the south side (fig.4.). By late summer the aphids Q:h. persicae and 1h_ brassicae) had spread over the vrhole· area. The rapid deterioration of the plants on the north side caused the aphids to leave and only plants on the south side retained aphids during vlinter.

In plot No.2 the cabbages along the eastern side had large colonies established by mid-November. Not until the final two months (December and January) did the aphids establish them-­ selves on the other plants of this plot. At the cessation of study (in January) aphid numbers were very high throughout the whole area.

The results of the year's population trends of~ tasmaniae in the cabbage plot are stmmarized in figure 34 (detail is e;i ven in Appendix 1). Adult M. tas~aniae vrere present all year except for b'To brief periods in October a..11.d November. InJa:te summer adult numbers steadily decreased but a few were present most of the winter. In November numbers multiplied rapidly and had reached a peak when the study terminated. A total of 4267 adults had been counted.

Although there was an apparent absence of pupae during

Februa!"J, in March they rapidly increa::'ed to an autumn peak.

Pupae were absent only during late winter. Appendix 3 gives the totals and types of pupae counted in the plots. Normal pupae (P)

3 were always the most numerous but dead (F'"'C), spent (P ), and para- sitized (p•) pupae 1vere all found in substantial numbers. 1997 pu:pae were observed.

Larval ~ tasmaniae were found in greater numbers (5257) than any other stage of the lacewing's life history. Larvae were present for ten months of the year, as were their prey, the aphids.

The total number of larvae counted includes larvae of all ages, many of which were small first instars. 41 Eggs were laid upon all parts of the vegetation for

most of the year, for~J-two being counted in the June-July-August

:period. In late October eggs were laid in vast numbers.

The author correlated temperature and :M. tasmaniae

nwnbers counted (fig.35). temperatures fell steadily in

autumn to their lowest level in May, after which they fluctuated

about 45°F until early September when they increased. Although

there is some correlation between the two l:i.nes of the graph it

is apparent that temperature alone does not determine population

size of ~ tasmaniae.

Plant shape (open, normal, tight), plant vigour (good,

medium, poor) and aphid numbers (high, medium, low, none) influence

the numbers of ~ tasmaniae counted per plant. The lacewings were

most common on those cabbages which were open leaved, vigorous and

supporting many aphids (e. g. plBnt 69 with 437 hemerobiids), but

were less common on ulants with few aphids, tight foliage and poor

vigour (e.g. plant 55 with 2 hemerobiids). The correlation of

these ca1:;hage characteristics (each cabtage was allotted marks for

advantageous characteristics) with the number of lace'l'rings counted

revealed several anomalies where tideal' plants had supported few lacewings and Yisa. versa. An example plant cabbage number 70 which harboured 92 lacevrings. This plant was given a low rating,

as a host plant, because it was not grow::.ng well, was tight leafed

and had fevr aphids. By virtue of its position between two exceed-

ingly good host plants this oabnage was able to support more lacewings

than it would have if growing elsewhere in the plot. 'non con- forming' plants could be ,explained in a similar maJmer. 42 In conclusion, it can he seen that all .the above factors plus temperature influence !h_ tasmaniae numbers found in an area.

The availa.hili ty of food would he thee greatest single factor de- termining population size of this predator.

In the final count (No.76) sixteen of the cabbages were completely dismantled, and all lacewings were counted, in an attempt to estimate the error in the sampling method used by the author. The results of this count are shown in Table 5.

For 16 cahbages. For totg_l of I)lot 2

Count 75 Count 76 Difference Count 75 75 + the difference

X 109 168 35% 155 238 p 0 21 1oo;s 1 100

1 29 264 89Js 59 536

X 154 128 flight 226 226 n :s p 192 218 pop. gvrth. 265 265

1 307 Lc73 51~;s 1~-65 716

Totals 1171 2081

X Adults p Pupae 1 Iv!icromus tasmaniae. 1 Larvae I A Population from plants.

B Population from ground vegetation.

Table 5. The final cabbage cotmt, number 76.

There existed considerable difference in four of the categories 43 of the two counts (i.e. the three plant inhabiting stages and

larva found up on the ground). It was possible to estimate the total number of hemerobiids (2081) present in the area at the end of the stuqy. The protective colouration, smallness of the, insects an:l abund.ance of vegetation a~l combined to make obser~ vations of the lacewing difficult.

As the study progressed it became apparent that many hemerobiids were inhabiting fallen vegetation. Originally ,

cole1ted on fallen leaves vrere crecli ted to the total of the nearest plant, but not after :March, 1963. (Appendix 2

s the totals collected from this part of the environment and the dates unon wi:ich.they were counted). A total of 11,544 lacewin13s were observed in the cabbage plots during the study

A..nd 57.2 ;:; (6591) were found on the:'fallen vegetation. Ylhen it is consi:iered leaves fell only in autunm ~o:md summer it is apparent that this of the environment was most favoured.

The lacewine;s vrere ahrays found on those parts of the plant pro­ viding most shelter and when the gi'ound vegetation supplied an abundance of cover it was reac:'Lily inhabited.

Additional information on the autunm hemerobiid popu­ lation was gained from a Pa.panui vegetable garden between January and May 1963. At the start of the stu~ large populations of both hemerobiids and A. zealandica were present upon a row of lettuces. These plants deteriorated durinc; the next three months (January to April) and the aphids established themselves upon nearby pumpkins, where the lacewings continued to prey upon them. Vri th the onset of cold weather, the pumpkins wilted and 4lt.

were removed. The auhids next auueared on beans and M. tafunaniae ~ -- -- followed. The 'ceans did not survive the frosts and died. Late

in May, the bea..'1S had gone but celery w~s growing well. Both

aphids and lacevQngs thrived when sheltered by the leaves. Through-

out the period, a gradual decline, in lacewing numbers was observed

as food became scarce, parasitization increased and temperatures

decreased.

Tvr9 small plots of' wheat were planted in the garden in

winter 1963. By September the plants were inhabited by

H.!l.oidosiuhum padi (the cereal aphid) in sufficient numbers for the

support of many l~oawings by e~ly October. As the aphid numbers

increased, the plants deteriorated and the aphids had left by

December. The cereal turned brown ~nd s~eltered many adult

N. tasmaniae. Regular population counts v1ere made durin.:; this

period.

A rhubarb patch was the immediate neighbour to the

ca.b1Jages of' plot No.2. This vegetable provided good shelter and

a supply of' aphids. (Appendix 5 gives the detailed information

collected from this patch). Although female hemerobiids predom-

inated in early counts the males dominated after mid-December· when

no aphids were present on these plants.

2. Mortality in natural populations of' :M. tasmaniae.

Throughout the study the author counted dead lacewings

(in the cab"bages) and endeavoured to establish the c~se of' death. " Figure 36 (A' shows the monthly total dead hemerobiids observed

and numbers of adults and larvae killed by spiders. Figure 36 (3) is an analysis of' the deaths. Spiclers killed many adult lacevQngs 45 (marked and un-marked) but the maj ori PJ died of unknown causes.

Spiders were responsible for 60% of the larvaJ. deaths observed.

Many pupae were parasitized by A. zealandica.

3. Marking and releasing of adult M. tasmaniae.

Eleven batches (140 individuals) of marked adult~ tasmaniae were released into the cabbage plots. Table 6 summar- izes the results obtained from these experiments. It can be seen that in seven out of nine com~1leted observations marked insects vrere recounted for more than thirty days after releasing, anl in three 1Jatches were present for fifty clays or more.

Date Last Number Number Time Symbol J.n released record released counted field

1 B 27 - 1 20 - 3 12 16 53 G 28 - 1 12 - 2 12 3 16 4 R 3 - 2. 1 }+ - 3 12 19 40 Gy 9 - 2 30 - 3 12 26 50 R· I 12 - 2' 22 - 3 12 26 39 3 G· I 19 - 2 9 - 4 16 18 50 B· 6 - 3 9 - h. 12 10 35 2 ·R 11 - 3 29 - 4 16 34 34 R· 27- 7 7 - 8 12 5 12 R• 15 - 12 18 - 1 12 16 35* ·R 22 - 12 26 - 1 12 6 36*

B G Green * Incomplete R Red 1-4 movements sho~vn in fig 37. Gy Gray

Table 6, :Mi cromus tasmaniae marking and releasing. 46 The movements of four eelected marked adult batches are

shown in figure 37. The greatest distance covered by an a.dul t

(bottom right diagram) which was thirteen feet. JU though move- ments to the surrounding vegetation vrere not checked, some adults were found outside the area (top left diagram). Most adults did not move far from the cabbage upon which they b.ad been released.

In the spring of 1963 the cabbage plot lacewing popu- lation was slow O.eveloping. The author considered :u. tasma.niae ingression into the cabbages was possit,le, as food a.nd cover were abundant. :M. tasmaniae wa.s already well esta-blished in the wheat and rhuba.rb patches. Fif-b.r-eix U. tasmaniae inagines captured in the rhul1arb were marked and released into the rhubarb between

Ooto1·er 26th a,nd november 27th. Thirty-seven of these a.dul ts were recaptured in the rhubarb e.nd tvro were founcl in the ce.bbage plot, one foot a7ra:y.

L~. Hicromus tasmaniae flic;ht.

This lacevring is not a strong flier. It drifts slovrly

through the air 1 its large ·wings being influenced by ary ecldy of air it rreets. Duslt: :Ls the time of maXir1um a.cti vi ty and on the

24th November observations were made (6.~.0 - 7.53 pm.) at the rhubarb patch. The evening was clear, vrarm (60°F) and calm.

Forty-eight insect action~ (flights between plants) were counted, twenty of ·which were short.

One female r.:. tasmaniae flew out of the rhubarb to some roses, then to a flower e.na. finally to a lemon tree, a total o.ist:::.nce of thirty feet vrb.ich was covered in about eight minutes.

Many adults vrere seen drifting among the flov;er beds. ::'orne 47 adults flew into nearby parsley and fed upon aphids.

Twenty-two a

Irises.

December 1st was a clear, calm night with temperatures about 61°F. Movements were observed between 5.10 and 7.~-5 pm:. e.nd seventy one insect actions were counted. Tvrenty-three adults left the area. .Although many adults stood on the tope of the leaves> they did not fly off. Those lacevlings which left the area usually climbed twenty or thirty feet vertically in the air before slovrly drifting away.

The light trapping at Fendal ton between r:ovember 1963 and March 1964 resulted in the capture of 1800 lacevTings ~ tasmaniae 1685 and.£.:.. maorioa 115). The detAils of this colloctins are given in appendix 6 which show·s that the per­ centage of females attr~;wted to lie:hts was slightly higher than that of males. Figure 38 compares the nie;htly total CB.ptured vii th the temperature at 9 pm. on these evenings.

Light trapping at Lincolh College produced smaller numbers of hemerobiids than did the traps at Fendalton. The results obtained from this source are rel)resented by figure 39

(the details are given in appendix 7).

The Lincoln College suction trap provi<:.l.ed detailed in- formation on the times of M. tasmaniae flights. This :"peoies

may fly at any time of day or night vTi th maximum activity occurring at dusk or a little after. Figure ~.0 represents a section of the data provided from this source and illustrates 48 times at which each sex flew. The sexes flew in equal numbers (58 9 : 59 cS). The results are similar to those obtained by Dr. T. Lewis at Rothamstead, England (Pers.comm.) who captured some species of lacewine over 17 hours each day, with me~'Cimum activity at 2300 G.M.T. Most species, he said, flew at night wi. th two surges of activity, one at about tilid­ night and the other around or just after sunset. 4-9

CRAFTER V. PREDATORS , PARASITES AND VIRUSES.

Micromus tasmaniae has at least one (possibly three) parasites, five p:':'edators and a virus.

1. Parasites.

a. Anachris zealandica (Ashmead)

(Order : Hymenoptera.

Super family : Cynipoidea.

Family : Figitidae.)

This insect is a widespread prima;l:'1J parasite of lh_ tasmaniae. The actul t A. zealandica oviposi ts in the skin of third instar lacewing la.rvae. Many adult yarasi tes nay lay in one host, but only one para::i tic larva develops. The lacewing la.rva pupates 1')ut does not moult 3 - I+ days after spinning the cocoon, as would an unparasitized prepupa. After twenty d•JYS, a numbr-r of clear spines can be seen protru(ling through the in- tegument of the host. The A. zealandica larva leaves the hosm when only the l:atter 1 s head has not been eaten, approximately 21 d~ys after oviposition.

The larva (fig.4-1) is 0.72 mms long, has two rows of eight spines along its dorsal surface, and a loose cuticle. The heal capsule is ohitinized and supports small mandib].es. The head is curved ventrally under the thorax. Vfuen fee.ding the internal organs of the abdonen move backwards anrl forwards, es- pecially in the caudal prolongation. The abdomen is tapered to the anal opening.

The larval A. zealanc-lica consumes all of its host. If 50 the cocoon is damaged and an exit is present, the larva may

The parasite larva at this is ooloured dark gray tut turns white after secreting a large bl'3.ck ffi

The form of the larva changes as it becomes sack-like. The integument is shed and the white pupa, which has an insectine shape, r8mains. During the next 13 days the pupa changes from

··;hi te to black, the compound eyes, thoracic appendages, antenns.e, abdominal segments and the constriction between the thora:x: and abdomen, are visible through the thin· transparent pupal skin.

Movements of the pre imago split the pupa down the mid­ n.orsal 1ine ani. the combined actions of legs and l:;ody push the skin posteriorally. Once the wings are free·i from their cases

The ad.ul t A. chews throw:;h the cocoon, forming an exit through w~1ich :tt escapes, le:wing the preimaginal moult in the cell. Many adults are una·~ le to free themselves from the pupal skin and die.

The small, shiny bl::tck aC •. ul t is 2. 5 mms in length.

The heavily chi tinized head has l:J.rge black compound ,;yes, large mandibles and short moniliform antennae (fig. 1.,.1). neck is not visible. The tra:'lsparent, cone-shaped :E'orevrings are larger th'ln the irridescent hi'1d'trings which have setaceous posterior margins. Each forewing 1•ears a. large conspicuous stigma. The narrow link betvreen thorax and abdomen is formed by the two most anterior abdominal segments. The 1)ulk of the abdomen comprises the remaining segments which are broad and expanded. Each long, slender bears an apical spine and claw. The adult is covered in m-tcrotrichia: l'ri th macrotrichia in isolated clumps. It was not 51 possible to sex the adults superficially although identified

were larger than the average adult.

The presence of A:_ zealandioa in a M. ta.smaniae cocoon may 1)e inCiioateCi by a colour change in the silk from white to yellow.

Hating. The fem8le is approached 'Gy the male who rubs his antennae along hers. Tfue stationary female is mounted, the male gripping her thora.x with his claws. As their posteriors come into contact the male 1 s head and thora.."'l: start to svray rhythmically from side to side, sweeping his antennae across those of the female. The short precess of mating may be re- peated a number of times.

Oviposition.

strongly, walk much of the time. As they walk their

B.ntenna.e are spread laterally, vibrating against the substrate.

The aCiult m~w investigate many ol)jects with its antennae. If the

ect is a third ins tar }t1. _:!::~aniae, oviposition s place immediately (younger larvae are not attacked). The female hymen­ opteran spreads her , doubles her a1~·domen under her thorax and ejects the ovipositor in the direction of the host s. The ovipositor is a fine, transparent tube which is forced into the host 1 s thorax. The larval 1acew~.n:; reacts to the att<:.wk by

Walkins away c>.nd by a violent waving of the abdomen. The parasite follov;s its prey, and several attacks may be made oy up to four adults sim,Jltaneously, but the intensity of the attack quickly wanes.

The are extremely active in the presence of 52 light but are inactive in its absence. The head and thorax of

the inactive adult is twisted in an arc :ro that the whole body

is curved in a semi-circle. Tem·Jeratures may exceed 65°F but

the imago in darkness does not move. A. zealandica, will remain -----'-~.;;.;.._

active even at 4-0°F if the light intensity is not diminished.

Winter Spring. Autumn 1962 1963

Oviposition to 20 21 25 25 appearance of larva. Larva to Pupa 6 8 13 151 Pupa to emergence 13 24- 33 Emergence to death 30+ 39 60 60 t------~-- Total 69+ 92 131 236

+ approximate figure.

Tal:le 7. Seasonal life histories of' iL'1achr:l.s zealandica in days.

In all seasons a similar :i nterva1 is to.ken between

oviposition and lerval emergence (Table 7). There is a slow-

ing c.1ovm of' develop-' ment as the temperatures drop. This figure

shows the rate of rlevelopment of' ~ zealandica during winter

1962 and winter 1963. The former season was mild and warm and

only 4-6 d.ays were spent as a pupa.• The latter season w~s cold

and long in which 151 riays '.rere spent in pupation. A. zealan.3.ica

ove~m.nters as a prepupa or pupa.

A. zealandica was found in 1:·rassicas, vegetables,

thistles and cereals in Hawkes Bay, Taranaki, Kaikoura and

Canterbury. It is probabl~ that the species is widely distrib- uted throughout New Zeal::md. In the Styx chou moellier the 53 highest parasite numbers were recorded upon thistles along the western edge, fevr being foun:i inside the crop. Inside the crop it was always cold (35 - 40°F) and illumination poor as the c:'l.nopy of leaves disrupts the penetration of light. The low light in­ tensity and low temperatures may make the environment unsuitable for A. zealandica which remained round the edge.

The annual cycle of the parasite is such that only one

(autumn) population peak is reached. A. zea.landica e.dul ts were present in the chou moellier from January to :Me.y 1963. In spring

1963, the first b_ zeBlandica imago was found in the wheat patch on the 1st D2cember when there was one actul t lh. tasma.niae present.

'i!hen the rhubarb plot contained. 24 adult hemerobiids anc1 19 larvae

(Ilecember 5th) the presence of one pare.si te a'l.ul t was noted. In the cabbages it ·,-.•as not until December 29th that the firs.t ~ ~ l:mdica was Cliscoverect, with 339 hemerobiids ( 194 adults, 29 pupe.e and 1 'S6 larvae). The late inva:::·i on of the cahl·<>ge plot >y the parasite :i_s ~~iscnsseri later in this chapter where it is attri1m- ted to the 'searching' metho:s used by this insect. Once este.bli;·hed ~.n the babi tat the parasite numbers increase rapidly.

The parasite larva a~'peo.rs in the hemerobiid cocoon a~rproxima tely three weeks after oviposition. 2eventeen days (14.1.64) q£ter the observation of the first adult (29.12. 63), the parasitized pupae were found in large nurr.bers, suggestins tha.t no A. zealandica were present ·before late December in the cabbages.

During late summer and autumn the parasite numters in­ crease rapidly to a peal: in lfarch after which there is a rapid decline. The last adults were observed at Styx on the 23th April and on the 5th April (1963) in the cabbage plot.

The absence of' A. zealandica f'rom the caKage plot for nine months cannot be fully explained. The late appe~rance of' the a.dul ts in the brassicas can be attributed to their lace of' reproductive success on this vegetable unles laoe~~ng numbers are very high. ':'.'hen 'searching' f'or larval lacevdngs, f::.:._ zea.l- andica aclul ts quickly zig-zag up a plant and along the leaves

"before flying to the next plant. 'rhe course taken by the insect, when on the plant, includes few lateral diversions. Thts tech- nique is ideal for cereal crops (e. 3· wheat) because the H. tasmaniae larvae are found on the vegetation as the insect walks upwards. The smooth upper surfaces of the rhu'oarb leaves rrovided little protection for the lacewing J.e.rvae w:.ich lay along the veins, whc:re their predators easily found. them. However the pitted cab1~age leaves provLleCl. shelter for the la.rva an : they were not found by their para.si te. The 'searching' technique of the para.- site is not as effective in brassicas as it is i.n cereals.

In May 1963 collections of M. tasmanie.e were made from different localities and they showed the pa~asite infestation characteristic of autumn (taole ~).

Pupae Adults Locality Normal Parasitized Dead Total zealand:i.ca.

Hawkes Bay 488 236 201 925 Many

Taranaki 306 102. 47 355 None Canterbury 164 55 143 362 None 858 393 391 1642

Table 8. Analysis of~ tasmaniae Pupae collected in May, 1963. 55 Four collections were made in Hawkes Bay and of 925 pupae, 25jlo were parasitized. Three Taranaki collections produced 355 pu:pae of which 29Jla contained papasi tized. In all three areas many pupae were dead but only in Hawkes were adult parasites present in the field.

b. Hvmeno·oterous uarasi te No.2.

This hymenopteran belongs to the family Ichneumonidae and ·is Dossi<::Jly a member of the genus Hemi teles. It wa.s not possible to establish that this is primary parasite: it may be a secondary (i.e. a parasite of zealandica). Only ten speci- mens have been found, nine larvae and one adult, in the chou moellier at Styx~

The larva of this spec~ es is small ( 1. 8 mm), maggot- like and gray with transparent integument. The .l9.rva which spins a cocoon s two days to do so. Little spinning occurs on the first day. The elliptic :::.1, finely spun cocoon being com- pleted about itself on the second ::Lay. The larva excretes a mass of brovm pellets (which are deposited at one end of the cell),and then pupates.

The larval skin is remo1red by a series of body contor­ tions and the white pupa rer.1ains. The large compound eyes of the pupa are the first structures pigmented. The pupal abdomen is doubled under itself and the ovipositor lies along the mid­ ventral line. Yiin13 buds and legs are forme:l as in A. zealandica.

The pupa is re to emerge from the cocoon when it is almost completely black.

The pupal skin splits and the ima13o emerges, expands 56 its wings, moves its legs, antennae and mouthparts before

chewing through the silk of the cocoon to freedom. The adults

are very active insects which fly strongly. Figure 42 (A & B)

shows the form and structure of the adult. They have extremely long legs, stree.mlined boiLies and elongate anal appenclages.

Adults which emerged from cocoons mated, and one

It was not known whether or not tl:is larva had 'c·een previously

attacked by A. zealandica.

ACJ.ul ts of this species were -kept alive successfully

on e. honey and water diet for five weeks in 1 Agee 1 preserving

j 9.rs.

c. H,ymenonterous parasite No.3.

1\.n unidentified b_ymenopteran larva v;as fo~lncl in the

abdomen of an acJ.ul t female H. tRsmaniae. The larva was j_dentical to the larva of ~ zealandioa, h.:winc; the same shape, size, two rm'\s of e:i_ght dorsal Rpines, small hr;ar0L' caudal prolongat:_on and ohitinizedmandibles. The host was heal thy and ,~ra.vid with a

greatly distended abdomen. It was not yossible to establish whether the parasite was in the alimentary canal or free in. the abdomeno No other M. tasmaniae adults were found pare:si tized.

2. Predators.

a. .SPiders.

Spiders l'rere present in all parts of the M. tasnaniae

Adult M. tasmaniae could. walk ou-: of spid8rs webs but larvae vrere tre.pped in the silk. These predators ;·rere responsible for many deaths in autumn and lHte summer, and of the 167 deaths 57 recorded in the cabbage plot, 70 were at:bributed to spiders.

The numerous small s:piJers, as a s;roup, represented a most import­ ant predator ofthe l

b. Psocids.

Psocids were found in all environments occupied by !::h_ tasmaniae. These GElAll insects are able to suck lacewing eggs, but it is tEll:i.kely that they would cause great losses as they ap:peare i to have c;reat rl:i.ff:Lcul-bJ penetratin.c; the chorion of the

c. Heminteran.

A-.11 unidentified anthocorid nymph, was found to be pre­ d'3.ceous upon the pupa of 1.1. ta:::maniae. The rostrum of this small

(, 5rnm) red insect >7as poked throuc;h the silk of the cocoon until the pupa rras contacteo.• Anthocorids <'''.!'8 knom1 to 'oe predatory upon a1;hius, thrips, insect eg,::s an::1 sra,?,ll le:pic1o;_:Jterous larvae rut are not restr:.ct8d in their hosts. It was not pos:oitle to raise the nymphs to maturi~J.

d. Coleontera.

Lady1,ird larvae and adults '/:ere the most B{;gressi ve predators of the aphid community. These insects, althoush present all year, did not reach high num'::Jers in the cabbage plot until mid-summer. Four M• tasmaniae deaths ~'rere recorded as being caused by these insects. All str:1.ges of lace·Hing are· vulneraole to ladyoird predation.

e. Mites.

Large numbers of mites were sometimes founo. in la,cew:i.ng cocoons; they were probably scavengers, feeding on dead pupae. 58 It was not known how the mites penetrated the silken mesh of the cocoon or the conc'J.ition (~leau.or alive) of the pupa at the time of entry.

3. Virus.

In a.utunn1 and vrinter ~ tasmaniae larvae may die as result of virus infection. A spontaneous epidemic may occur in experimental populations if deacl a)hids are n·: t removed.

Pupating larval E.!:_ tasmaniae incorporatins dead a'Jhids in their cocoons freq ~ently die. The integument of the dearl larva or pu:9a turns black with complc·te liquefaction of the body con- tents, 1mt does not rupture. Al thouc;h the dead im ect dehydrates, no decrease in virus potency occurs.

Any virus particle introduced into the ~•ody of its host will regenerate itself. Host reaction l:y the forming of molecular :90lyhedra provides a site for virus concentration.

The steady increase of virus particles leads to death of the cell and eventually of the host. A;?hids vreTe :lipped i.nto solutions made from clead I'll. tasmania.e larvae end. pupae, and the aphicls were then fed to six starved adult and to 15 starved larval lacewings. One adult died of virus infection c·ut five survived. Of the larva which pupated, eight were parasitized by b._ zealandica, five survived and two pupae died (possi'oly of· virus infection}.

The 'virus' solutions after fractionating produced four layers which were isola ted. and spun in the Serval. .:.lides, made from the resulting pellets ~'hovred: Description. Layer.

A consisted of fine dots

Opalescent B particles were domina~t

1------General G many bacteria opalescence

1------Pigmented + D bacteria and aggregations \--diLl>..--" p e 11 e t of granular material.

Seven of the 167 lacewing deaths recorded in the cabbage plot were due to virus j.nfection. . Although bacteria were iso- lated, the putridity characteristic of bacterial action was not seen ,and it is probable that none of the deaths observed was clue to bacterial infection. 60 CHAPTER VI. BIOLOGICAL CO::TTROL OF APHIDS.

1. Biological Control.

In recent years aphids he.ve been exposed to a range of chemical sprays of varying to:x:ioi ty. These insects have a high reproductive potential and a rapid 1-mildup of immunities should occur within the next decade. The sprays frequently contain dangerous residuals and are costly, l)ut can be relied upon to provide immediate control.

Biologic.g.l cont!'ol by foste!'ing natural enemies is initially expensive but may become a che:=tp, effective, long term control measure. This thesis has provideJ basic infor- ma tion a"bout one na;turnl enemy of the aphid i.e. !'ilicromus tasmaniae. This lacewing, ha.s a".number of advantages as a biologic.3l control e.gent (Chapter VIII).

only two insects which oou:.d be used for aphid control The author observed three or four hymenopteran aphid parasites which are present in the field before the spring aphid flights occur. Research could reveal their potential a.s bioJ,ogical control agents.

In Cr,lifornia a Jarge, aggressive ladybird is being used successfully as a·r, aphid predator. There, a.s in Australia, these beetles may be 'bought by the pound for releasing among pest infested crops. Th:i.s ladybird has recently been introduced to

New Zealand but has yet to be studied properly. :2ince aphids affect the economy of Nevr Zealand, a full sce.le ecological pro- 61

gre.mme, sl}ould be initiated. Puhlic money has been spent upon

1 aphid vrarnins systems 1 -rd thout properly planning the prelimin- a.T"J experiments. It is 5ood that the Government provides funds for aphid research but the resulting research should be scien­ tific s.nd continued to completion.

The author is convinced that M. tasmaniae could be useful as a biological control !?.gent and the~t B. m-9.o:c-ica would also :prove to r)e effective if studied. No large scale field , t8st was carried out during the course of this thesis but there is every ind.ication that such a test would prove t:r. tasmaniae to 1'e an effective control agent. Both imagines an:i larvae could be released. as predators. Larvae are the r1o~t difficult sta::::e to keep in captivity anc1 would te the most effective in the field. '!'he scatterin,:; of egs:s 8.1)out a pest environment would oe the 1)est way to introduce these prec1ators. Imasines oo,Jld be releac:ed, !yut cLue to the c(ifficul ty in raidng large numl,ers, it woulo. be impractica1Jle and expensive.

2. Outline of a M. tasmaniae rearing progremme.

The aim of such a ppograwue should be to produce large c:upplies of H. tasmaniae egc:,s which could be distributed at sl10rt notice to crops.

a. Eauipment.

Cages : 2 1 by 2 1 by 2 1 made of four gla,ss walls (or two glass and two hardboard), a wooden floor, a tin tray sliding above the wooden base, a wooden roof vri th a gauzed central por- tion (for ventilation). The frameworli is punctured by holes for ventilation and for gassing with care on dioxide (fig. 4-3 ( 1)) ~ 62 The roof would be fitted with an outer fla.nge to permit close contact with the walls of the case (fig.43 (2)).

Feeder. (Fig.43 (3)). This consists of a reservoir of honey and Tiater inverted into a circular bath. Gauze pre- vents the aciul t lacewings from drmming but does not impede feeding. The lateral 'waJ.kups' permit many insects to feed simultaneously. One feeder would serve each cage.

Pupation pipes. (Fig. 43 (4)). These are designed to attract pupating larvae. The two sides of pipe are hinged doi'm the midline so that the pipe may be closed (to permit pupat:Lon) and opened (to let the a.o.ults escape). The 6 11 x 1 11 pip~Jelevated from the cage floor by two sl-:ort supports.

b. Breeding replacement M. tasmaniae adults.

Each cage could hou:::e 10-15000 adu1 t J..<:1.cevrings. Dried lP.aves may be placed in the cages to provide shelter. V•ihen rearine replacement ao.ul ts, the programme couJ.d be subdi videcl into a series of steps i.e.

a) l'emoving eggs from breeding adu1 ts,

b) hatching the eggs (in an emp"bJ cage) ,

c) feeding the larvae,

d) providing sites for larval yupation,

e) placing the pupation pipes in empty cages.

f) feeding the imagines aphids, to stimuJ.ate them

to mate and to oviposit.

r:tep a) wouJ.d involve the remova1 of the cotton wool. strins from the cages and their replacement by new pieces of wool.

The eggs would hatch (90-100JS) in 6-8 cl.ays at 65°F (Step b). The larvae ·would leave the cotton wool in search of food.

Step c) would present the major difficulvJ in this metho:B.. Techniques for raising aphids 'in bulk 1 have been developed but would need to be perfected (Chapter II 2. a).

Reserve supplies of aphids must be inexhaustitrle so as to counter any failure in culturing. Aphids will thrive if growing plants, strong illumination (bra.ckets of fluorescent tubes), circulating air and tempere,tures about 70°F are pro- vide d. The aphids can easily be raised on the required scale once the equipment has been assembled.

The larval lace·wings must be fed aphids e,s soon as they emerge from the eggs or else cannibalism will occur. The larvae should always be fed 'detritus free' nymphs. The aphids are shaken off the plants on to large (l~' x4') perspex sheets which contain a small Glectrostatic field of sufficient force to attract all the old maul ts. The aphids st,aken from these sheets are quite clean. If the larvae are well fed the time spent as lar:vae will be brief iiDd all the larvae will pupate at the same time.

The pupation pipes are holes in which the larvae can pupate (step d). Numbers of pipes placed in each cage would cater for all the larvae and allow the populations to be easily subdivided. The pipes are removed when aiL the la.rvae have spun

(step e~ and are placed in the cages in vrhich the new breeding popul8.tion is to be established. The pupae could be used to establish a new popula.tion or to rejuvenate ageing stock.

c. Rearing !!!. tEtsma.niae for ls.rge scale releasins• The adult lacewings will mate and begin laying imrned- iately if provided with aphids. They v1ill survive for three to four months on hoi1ey-vrater solutions from the feeder. It may l,e vrorthvrhile to sex the a.dul t le.cevrings and to remove most of the males, which ViOUld allow 2. grea.ter number of females to be kept in each oae;e .. Males could be reo zed easily by an experienced technician.

'':ben egss are req·.. ire:i, a large mass of aphids (e. g. two saua:c'e ~:_nches which r8pre sents approx.1 ,000 individuals), should be put in each cage. The special cotton-wool hearing lid. should renlace the normal top. Small hooks could. be use·~•- to hold vrool to the lid. Adult tasmaniae will lay two to four days being provided with aphids.

The eggs would be removed when the cotton-wool is re- placed. The cottonwool should be placed in containers

and •iisnerse·i throur:rhv the i~ested cron.- The eggs must be pro- vided 7ri th a humidity. vlill occur

6-8 ays after on , 1•fi th normal s temp9ratures. The larvae will crawl out of a (~ e.rk conta:J.ner toward. a·l..righted exit.

The d2.rkness may prevent crmnibalism amongst the larvae.

':.'hen the cages are eT'lptied or the insects may be anaethe.ti::;ed with car>:, on dioxide; they will fall into the tin tray a:nd c£:.n "be removed.• Spent and. aginc; adults could be treated in tl:is way and then :::•r-;,1eased into an sted crop.

10,000 s· in a cage could 500,000 eggs wh:Ech could ;;roduce adults in 3-Lt- vreeks. The 500 ,000 ( 6 6: 9 ) adults would be ac·le to produce e)·, out 10 nillion egc;s 11~1ich w·ould be 65

larvae in seven days. The total environment~l population supplied from the stock of one cage could be over 13 million after only a month. In practice such a huge population may not be produced in such a short time but it demonstrated the reproductive potential of M. tasmaniae. 66

CFJJ\PTER VII. INTERPOPULATION CROSSES.

1. Crossing Pouulations.

Micromus tasmani ae populations may reach high numbers in most localities in ·which hemipterans survive. The lowlands of' New Zealand (sea level to 1500 f'eet) are continuous, encircling the alps. Cook f'orms a 1iarrier to insect migration, but winds and the movement of vec;et.'1bles between the two islands allows ?f. tasmaniae to have a complete New Zealand distribution

To esta1;lish whether morphol , genitical or be­ havioural have arisen in the tasmaniae po1ulation of New Zeala..11d a eros test wa.s carried out. Adults were collected from three sites:

(i) Inglewood and I~epperton, TaranaJd.

(ii) , Havtkes '3ay.

(iii) LoY1er 2-b.rx, Canterbu~J.

The consisted. of three control and six cross populations. It was not possible to provide the lacevrings 'vri th aphids upon live plants. The experiment vras atter;pted in a glasshouse but only one population survived. The reason for the failure was not ascertaine~l_, but the presence of insecticides may have caused the failure.

The was repeated and results are summarized in Table 9. 67

c c Hh T t c t G h T o T h H t H o Parents 4·4- 4· 3 3·4- 3·3 3·3 2·3 3·3 3·3 3·3

Eggs 1 32 53 37 79 4- 11* 19 61 Larvae 1 32+ 49 35+ 73+ 3 12 15 51+ Pupae 1 28 40 30 33 2 10 13 34-

Imagines 1 22 40 29 31 1 8 12 30

Eggs 0 80::: 30= 17 19 0 20 2 27 Larvae 0 80::: 30= 15 10 0 20 2 27

c Ca._nterbu!"J Error

H Hawkes Jay + Larvae removed

T ::: Approximate value

Capitals ::: Ji!e.les Small letters ::: Females

f First filial f Second filial. 1 2

Ta1Jle 9. Results of interpopulation crossings.

The number of eggs laid 1~y the crosses varied betvteen one and seventy-nine, but each cross uroduced at least one vici.ble larva.

One or more adults were rearec::l. from the progeny of each of the crosses. Two of these f populations contained. less than two 1 adults, a._nd produced no offspring (i.e. the Canterbury control; and the Cantercu!"J female, Taranaki male cross) of the remaining seven crosses all laid eggs and produced second generation larvae (f ). 2 There Wr:>.s no evidence of behavioural or a morphological ba.rrier to reproduction, no major difference in chromosomal patterns in the three localities (as f larvae were vid..ble) and no genetical 1 68 barrier (as viable f were produced). 2 The experimental conditions were lmnatural, the adults living in close proximity in a jar, beingfed on honey and occasional

aphids, and in the absence of predators. As each cross contained

only a small number of adults the indi viclual (genetical, morpho- loeical etc.) ·weaknesses of the parents could have caused defects in the results. This, or chance alone (since the numbers ·Nere

small), may account for the failure of two crosses to produce f 2 larvae. Although the Canterbury control died., an iclentiaal popu- lation reared alongside procluced f larv2-e. 3

Hale Female Loce,li "bJ No. Average No. Average

c c 1 19

Hh 10 21. 12 20.6

T t 18 21.3 21 22

c h 15 21.2 16 21.9

c t 16 20.8 12 21.6

H c 15 20 14 21.3

H t 5 21.8 3 21.6

T c 1 21

T h 2 21.5 5 22.2

Total 82 20.9 84 21.6

Time in days.

Table 10. Length of pupation by progeny of inter popula.tion crosses.

Table 10 shovis·'the average time. of pupation. 1.'he cross pupae took no longer to develop than did the controls. 69 Examination of mounted specimens ·revealed no morpho­ logical differences 0etween the three selected groups of specimens.

The ex1;eriment revealed no ba,rrier to reproduction t·etween the lh. populations tested.

2. Variation due to sex, s;;eo.grauhic location and season.

Sexual dimorphism, geographical and sAasonal variation were investigated_ by statistical metl;odtJ. The length of the forevr.ing from its junction with the thorax to its cliste.l ex- tremi ty was measured. f: ..:u:mles comi~.ted of thirty individuals of' each sex from the three locali t:i.es.

of Variance

Source 2s .df f.:ls F

Seasons 997.5 1 997.5 10.9316 • 01

2ex 11~7!+0.5 1 147L~O. 5 161.5lt.14 • 001

:~easons (;~ ::'ex: 154.6 1 1511-• 6 1. 69l!j NS

10534.9 116 91.249

Total 26Lf.77. 5 119

Scale 1 unit = 36 mms.

Table 11. Analysis of variance of fore-wing length in and ferr.ales in the Ce_nterbu!"J ation during the spring and winter.

The signif'icant main effects indicate that there are clear sex and seasonal differences in wing lengths vrhile the non-significant interaction demonstre-tes that difference in

·.ving len.:;th 'between sea.sons is the erune for loth sexes. The 70 females are the larger sex.

Analysis of Variance.

Source Ss d£ Ks F

G·e ographice,l 168.52 2 168.52 .8649 NS

Se:c 17681.20 1 17681.20 181.4852 • 001

Creog. C'!.! Sex 1605.48 2 1605.l~ 8.2400 . 001

·::i thin 16952.00 17~· 97. ~25

Total 36407.20 179

Scale 1 unit = · 36 mms. Table 12. A::1?lysis of variance in fore-vring J.ength in males and fem:tles of Canterbury~ Hawkes 3ay and Tare.naki w·inter popul.~:.tionso

':l't'.ile the sex: m1dn effect is significant, as in the prev:tous ~m.alysis, the non-dsnificant geocraphice.l m.:::.in effect indic:ttes that w:i.nc lencth does not differ significantly over the three regions chosen. Eo·:rever a slight, thou~h si:-;:nificant inter-

·'?.ction tetvreen gPo3raphical distribution a.nd sex susgests that

-:ri th more widespread se.mpling, differences in fore-wing length v7i t'": geoz:::ra.phioal clistril:mtion might te found.

Geoe;re.phio variation was further exa.mined.. The average fore-wing length for :'loth sexes of :~even populations (Edgerol,

Northern rT. S. '.'! .. ~ Auckh.nd Isl8.nds, Chatham Island and four lfew

Zea.land popuL.1.tions), was plotted (fig.L,4).

In the 11. tasmaniae collc cted in summer e.nd spring (A) > size varied from north (smallest) to south (la.rgest) a..11d appeared to be a fQ11ction of latitude. 71 In the winter populations (B) there is no evidence to substantiate the trend indicated in (A). It is posdble that differing environmental conditions (e.g. a warm winter with no decrease in adult size) may account for these results.

More widespread collecting should solve this protlem. 72 CHAPTER VIII. DISCUSSION.

The interrelationships of two species of aphid (Eyzus

persiciae and :Srevicoryne brass1 cae), _Micromus tasmaniae and the

cynipoid parasite of 11. tasmaniae, Anachris zealandica were studied

and the relBtive numbers of the three from October through to April

are shoi'm diasramaticalJ.y in fi:;ure 45.

The first aphids came on to the plants early in October.

They increased steadily to a spring peak in la.te November and early

December. Flights occurred in Deceml::er a.nd alate aphids left the

haoi tat. The slight decline in December was caused cy heavy pre-

dation and by losses to the flights. The population steadily

incre;;wed in January and Februa!"J to a peal( in March. The cooler

temperatures and shorter clays initiated the second aphid flie;ht

(rEarch to April), after which numbers decreased; none were present

in Nay.

M:. tasmaniae appeared in November and increased to a peal< in January. In Februn.X"J a slight decline in hemerobiid numbers occurred, after v;hich the population recovered to reach the peak in March. An e:x:tremely rapid decline in late A=i:;:'il was caused by disease, prede.tion, starvation and unfavoura1;le clima.te.

b._ :;ealandica adults were present for 3-4 months of the year. They appeared first in late December after which they rapidly increased to a peeJc in mid-March. The parasite population declined rapidly in :March.

The late appearance of the stud.i.ed insects in spring may be attributed to the abnormally long 1rinter in 1963.

All the population changes are interrelated. The aphids 73 established themselves in small colonies in October. As the

tem:peratures increased the reproductive rate of the aphids in-

creasecl and many nymphs were 1:· orn. Although num1)ers increased

steadily many of the adults were parasitized by the numerous

small hymenopterans and dipterans present in spring. The average tem:perature for ~Tovember was 53.6°F (55.6°F in October) 1:·ut a;phid nunl)ers incre~tsed. al tho'.. lgh temperatures wsre low and pare.si tiz- ation heaVIJ.

The slight decline in aphid numbers was c:'msed by the losses to predation ani to the spring flie;hts. 'IL tasmaniae be- ----~- ca.me established in m:i.:l-Novemt.er and helped in elocli.nc'::· the aphid incree.se Ct'.lri:'lg December. T:Jr mid-Decem',:er the temperatures in- cr<"ased (mor:th avera::;e ·was 57. 2°F) , the plants were ;:ro7ring well and the re}'roducti ve rn.te of the aphids vras maximum. Colonies

~revr f!.U~ ckly e.nd new populations W'3re ec.tt=c~J.i_sl•ecl lJy aphids arr:i.vi:'l~ vri. th eaoh north-vrest wind in thi.2 month.

T'·e hemero8:. ids thrived and increased rap~_,u_y RS the

In late·,·Dec- en:cer A. :;:ealano.ic2. a.dul ts were observed iD thco field an-l they attacke.l the H. tasmaniae larvae, which nere present in large num'bers. ]\[any larvae were parasitized and three weeks after the appearance of the first p~1.rasi te aO.ul t, parasitized pupae were seen.

All populations increased in January as temperatures were high (afferage 63. 7°F). The parasites increased at the expense of the lacewings in February and. :.hrch. ~he e.phids were still in- creasins a1 thoush many p::.~erl?~tors suo~ as la.clyllirds and syrphids

YT8re aicun!:j the neuropterB.ns, dipterccn.s r:cnd hynenoptera.ns to re- cluce their numbers. The aphiJ.s reached. a peak in M9.rch at which

time many left the habitat as the plants deteriorate,).• Numbers

decrea.sed rapi,Uy until May '8'hen none were present in the field.•

In the absence of A. ze.<:J.lanrlica., ;'uring Ap1~il, M•. tasman-

iae num0ers rr::ached their hi'Shest figures. The lacewing decline vras also extremely rs,pid.

The cynipoid parasite zealandica vtas nresent 1_2:1 the locality for 3-L~ months, in which time it was very a,ctive and para-

si tized lacewing larvae. killed. only 2 9;~ of larvae 2..nd pupae collected in i1IB.y fror:1 Taranaki (the hi,shest re- corded % of lace"Jiin:;s attacked). The 29){; represents the 1:1a:~im11m influence this parr..si te has U}Jon the le.cewing population and is not exceedin::;ly hich.

T::e le.teness of the pe.ra.site's arrival in the ha;bitat indic::J,tes t:1n.t this s need not 1!e considered as an important pred.".tor of H. tas~aniae in spring, when the latter insect could be used as a ~:iolozice.l control agent of aphids. Even· if the :parasite were present in the habitat, it does not -prevent the le.cewins larva from feeding normally and S}Jinning. If a larva had 1')een released to eat a-phils, although it became parasitized, it would still eat

'cet·geen 14 and 66.

The parasite would not, therefore upset any.biological control programmes using !.:_ tasmaaia.e as a predator of e,phids.

In natural conditions the aphid predators have: little influence upon the huge aphi

Ho1:ever, the author observed an effect in spring of hymenopterans and dipterans which did much to limit the first aphid colonies. The lacewings eat more than two a.phids each per day, and in

January this would accotmt for 3-5000 aphids daily. The syrphids

"lvould remove similar quanti ties of aphids each day. T'ne most

voracious predator, the ladybirrl, did not ap~)ear until late January

and had no chance to effect prey numbers.

~las been suggestecl (chapter VI) as a bio- logical control a:;ent of aphids. It is important to find out all

that is possible about the likely movements of acmlts and larvae if

they were released, in large scale, upon crops needing aphid pro-

tection.

Aclul t :M. tasmaniae were marked and released into the cabcage plot. 'rhe results (Cha.!,)ter IV) showed that they did not move far from the noint of The greatest distance moved by an adult was thirteen feet. Tl'ro adult is long-lived in the field ~1ein3 found. up to 7{£ weeks after releasing. Only seven of 140 adults releasecl were killed 11y prea.ators. The 128.6% recoYery of me.rked. adults substantiates author's opinion that few adults will leaYe a ha'i;i tat if it contains food.

Dusk observatlons of lacewing activity (Chapter IV) showed that a(lul ts do lea1Te the environment at night, i.e. 4-5 lef't and only 6 returned. As observations were not made later in the evenings to see if th-9 a:iults rAturne~i, the results are inconclusi Ye. Ap~;endix 5 shows that the total population of the rhubarb did not fluctuate as would be expected if large scale emigration was taking place. In spring when adults and larvae may -oe released (for aphid control), flie;hts would not occur as ni:sht temperatures rarely exceed 4-5 0 F. Figure 38 sho7rs that this 76 temperature must be exceeded if hemerobiids are to fly in numbers.

Larval movements of M. tasmaniae could not be studied in the same way. The le.rvae feed all dny and are also active at dusk.

Proltided food is reasonably apessible, there is no reason why larvae should not remain present in a habitat. Larvae have not been ob- served leaving aphid infested vegetation.

There is clear evidence that M. tasmaniae populations will f:o1low the aphid concentrations. As plant comE tions alter, the size of aphid colonies is ~fected and so are the prede.tors. The aphid concentrations shifted in the chou moellier (Chapter IV) and the lacewing concentrations followed the same route. In a Papanui hornegarden and in the calJ''age l'lo"::s simile.r trends were observed.

'.'.'hen aDhid numbers decline almost to absence, E •.:tasmaniae adults may leave a habitat (as or;curred in the rhubarb). Harked adults d.id not leave the ar<>a wi"ils aphids were present, 'cut c1id so when a.uhids vrere scg.rce.

The author has sug.::sestei (Chapter VI) that E. ta.sTianiae be used in a:ohid control. The rearing and releasing of these in::-:ects on a large-scale was consiClerect anri shoi'm not to be !:iiffi­ cult. This insect has many adve.ntages, some of which are:

( 1) They show no evidence of leaving an aphid infested habitat.

(2) The M. tasmaniae population is concentrated in those reGions of the habitat sup:9orting most aphids.

(3) Adults end larvae eat only pest species (except syr:9hids).

(4) The females reproduce well, laying 50 to 100 esgs each. 77 (5) In summer a generation ta}.:es 22-28 days.

(6) Pred:·tion by spiders and zealandica does not cause extensive losses in spring.

(7) Adults are kBpt alive easily and are long lived.

(8) The species occurs natu:::-ally t~.roughout New

Zealand (figs. 30-31).

(9) H. tasmaniae, is common, as :ts shovm the rates of collecting (Appendix l1.), lisht trapping (Appendices 6 2-: 7) e.nd by oabl>age plot observations (Appenuix 1).

M. tasmaniae could be used as a biological control agent for aphids in spring when the ephid'.infestations c;::.use most d~mage to cereal crops. Th~~s insect r;o:1ld he on the plants 1vb.en the ,asing the cereal imports necessary at present. Only research eo.n reveal the full potential of these insects, ··mt they may rrell proluce a lone term and cheap control measure for aphids. 78

abd. a1:;domen h. f. a. ely. anterior clypeus ~n.• 1. "'-"'''"·~·al ::.o1)e an. anus h2T-.- h.ypan

pa. paramAres cl. dorsal p.oly. post cly]!eus d.• ':.y, dorsal blood Yessel pe. pe:licel distncardo pfr. palifer ·~.h.~. dead leaf pn. pronotum n, P. orsal p:;~.pD19. pr. prepupa pt. pterostigr:e. e. e~re pu. pupa e. • et;g burster eot. ectoproct sc. scape emp. errr;_:JO.J.i nm sol. sclerite cranium se .. seta. epi.s. e:picranial suture s.g.a. subgenita1 plate sm. :::u"'.mentum so. sole f. :fronB sp. spir~:wle I"' e. femur spm. spermatheca fr. fre!!.ulum spn. spine f.s frontal snture st. stipe st. D. stalk ase ga, c;alea stc;. ·a£ig:oa ge. cenea gl. e;oEapoprwses laterales ta. tarsus sone.rcus th. thore.:-: ti. tibia ti.s. tisial spur ~,_. 0ook to. trios or h .:L. tr. troohe,nter tri. tricho'Jotb.rium ts. tempore.!_ suture hf

d h 1-

Fig 2. Styx chou moellier in May 1963. Fig 3. Size variation in chou moellier plants. p:._oT TWO PLOT ONE

I I ~ubarb Qi 0 0: 8 I I 8 8 0 0 I 8 I eG I I I 8 I 8 80 88 8 8 I /w I I 0 u0r::~ s" I I ~N I 0 @ @ I 0(0 8 I 51) ~253 ,,"'"'/)

57) 54 @ / 8 ,"' (®/ sGG 0 ®§· C0 0 GG 8 8 @see 88 @ 8 8@GerC\ 28 ~ e~ 0 Wheat 0 80 I / Wheat : Q 0e 00 1 0 \:~ 2 3 4 feet. Fig.4. Distribution of the cabbages within the two plots. Numbers: plant references. Fig 5. Cabbages of plot number 1 in March 1963. Fig 7. Cylindrical grease trap .. Fig 8. G-r:dlUnd l evel wat er trap., e------

ma .p---- ___ _

----lb

Posterior

Fig. 9. Micromus tasmaniae. Top. Anterior head. Bottom. Mandibles. ant- __ ---

epi.s- __ _ ------d.c

------me ------st

------la.p

Fig.10. Micromus tasmaniae head, lateral. . I la.p----

Fig.11. Micromus tasmaniae mouth-parts Left. Labium. Right. Right maxilla, ventral. co------t r------

ti ----·

' ' ····emp

-.. ----t i.s

to

-----emp '• '-c Fig.12. Micromus tosmonioe leg. Left. Metothorocic leg. Right. Prothoroc i c tors us. 7 8 9

------ect ----~-

VII V Ill IX

_.. ar

'' ' ~.g.p. ' '' 'I 'I ' 'I 'pa I hy

7 8 g

------·ect

Fig. 13. Male and female ------· g I genitalia of Micromus tasmaniae. pt ' ''

A c

,'Ml J' 1 ___ - - --~..l.It'l:::.P::~~- ~ ~ M2 ',,t o 3 : i t.. , 1A \ Cu1 a 2A Cul b

' ' 8 '' fr----- _

D

M3 +4

14. Micromus tasmaniae wings. A Fore-wing venation. 8 Hind-wing venation. c Jugal lobe. D Frenulum. Fig 15. Sexual dimorphism in adult Micromus t_asmaniae .. _..._-d.b.v.

/-ti

6

1

Fig.16. Micromus tasmaniae third instar larva. ,sp ' 2

e_------

3

md------­ 1 la.p__ ------ma.p__ ----- 2

ant 3 ------w ------

5

6 \ 9 8 7 I I I I p B -~ ~-d.p

Fig. 17. M icromus tasmaniae pupa. A. Unidentified protruberance. B. Dorsal papilla, lateral view. HOURS

0 Lateral

72 Latera I

,m I I I 96 Dorsal

144 Dorsal

e.b abd, I ' ' '

1 6 8 Dorsal

Fig.18. Micromus tasmaniae egg development. A

B

Fig 19. Mi c r~ tasmaniae eggs • A. B. '.Vinte·r egg at f our weekso 65 00 OF 55 50 45 40

40 1.1) ~ 0 '"'0 c 30 ·- QJ E i= 20

10

FM AM J J AS 0 N OJ 1963 1964 Month r;;J First Ins tar ~ Second lnstar ~ Third lnstar D Total time spent as a larva Rg. 20. Duration of the larval stage 1n Micromus tasmaniae compared with average monthly temperatures. 14 ', 5 11 11 ' ' ' ' ' ' ' 2 2 3 4 ' ' ' ' ' ' 13 ' ' ' 9 18 25 5 4 5 3 2 ' ' ' ' ' ' ' ' 3 5 ' 11 5 3 5 ' . ' ' ' ' 12 ' ', 1 6 7 4 5 2 4 ' ' ' ' ' ', ' 2 3 2 ' ' ' ' ' 1 1 2 5 8 8 4 ' ', 1 2 3 ' ' ' ' 2 4 3 ' 2 ' ' ' ' ' ' ' ' Third in star ' ' ' 10 ' ' 11 21 35 42 16 29 2 ' (/) ' ' ' ' ...... ' ' ' ' ' ' c ' 3 6 2 5 1 ' :::> ' ' ' ' ' ' ' ' ' ' ' ' ' 9 5 3 ', 8 19 8 5 ' ' ' ' ' ' 3 3 5' ', 7 3 2 ' ' ' Second ins tar ' ' 30 1', 8 41 44 ' 2 ' ' ' ' 39 30 1C ' ' ' ' ' ' ' ' 7 71 46 18 1 ',, ' ' ' ' 2 1 ' ' ' ' First ·mstar ' 6 4 1 Scale. 1 unit = ·036mms.

1 2 3 4 5 6 7 8 9 10 11 12 Time tn days =-j g.21. The relationship of larval headwidth to age. ,la.p I I I

.rnd......

ant_. ... -

Fig.22. Moulting second instar larva of Micromus tasmanioe. X 21

Fig 23. Mi cromus t asmaniae cocoon. so

60

50

~40 0 u c ·- 30

10

F M A M J J A S 0 N D J 1963 1964 Month

Rg.24. Duration of pupation 1n Micromus tasmaniae. Fig. 25. Micromus tasmaniae pre-imaginal moult. A Lateral aspect. 8. Dorsal aspect. Spring Midnight Neon

12 2 4 6 8 10 12. 2 4 6 8 10 ...... 70 . .. u . ·' .. ... u .. ~ B r- r ...... 60 '· 10

20 '

140 30 L L (\) (\) ..D. ..0 § 38 ·. 40 ~ ... . z ,. •. 20 .. 50 l

.. 10 60

.. . n n ~ m B M 12 2 4 6 8 10 12 2 4 6 '0 10 Madntght Noon

Winter.

OFemale []Male

Fig.26. Comparison of imagine emergence times in two Micromus tasmaniae populations. Fig 27, Micromus tasmaniae larva feeding upon :Ma cro s iphu~ rosae. 70

If\ 50 L Q) .0 E :I c

"0 ..c 0. <( 25

20 / .' 20 ' 15 ,/ .. maximum ;" ,,"'...... __ ... \ 10 ,/ '-.~~ \'\, minimum ' 10 ' ' 5 ' .... , '·------· uneaten

F M A M J J A S 0 N D J 1963 1964 Month

Fig.28. Monthly aphid consumptions of Micromus tasmaniae larvae. Summer 1963 600

sco Hatched 997

"0 400 Unhatched 386 Q) ..c Total u 1383 +-' 0 ..c 300

L

Winter 1963 Da s taken Number 15 4 17 3 1 ~~ 13 Hatched 55 27 12 28 1 Unhatched 31 37 3 38 6 Total 39 1 40 1 43 2 44 1 46 2 48 1 50 1 53 1 Fig. 29. Incubation period of eggs of M icromus tasmaniae in summer and winter. ------.Paihia 2

·------Whangarei 2.3

Kaiwaka 3------~------Waiheke Is. 2

Massey 2------­ Waitakere 2------=.... Titirangi 2------Green Lane 2 N ------Maramarua 3 _,-Tauranga 3 ' ;Whaka ta ne 3 /:Opotiki 3 W-+--E '' ' ' I ' Piripiri 3-----­ ' I' Te Kuiti 3------·.:=--.. ·- ... S Taumarunui 3-, Leppert on 1·, ',_ ---Tolaga Bay 3 __ ... Gisborne 3 New PlymouthJ>­ ~:---- -L.Wa ikaremoana 2 Inglewood 1------~--~--

------Napier 2.3 ""···::.:·--·Hastings Marton 1------1 1.4 Bulls 3------Havelock North 4 Fblmerston North 2-- ---­ ... ":..:--·:=: ------Waipukarau 2.3 Levin 3------. ----::- <::··--·Hinerva 4 Otaki 1------­ ------~~---Takapau 1 Kapiti Is. 2------tf' ·-·Rakautatahi 4 Paekakariki 3---- '---Eketahuna 3 Karori 2------

' ' ' ' 'wairiuiomota Valley 2 Eastbourne------­ 2

KEY. As in figure 31 Fig.30. Distribution of Micromus tasmaniae m the North Island. .-Nelson I . ' ' N

L.Rotoiti 4-----­ W-+--E Murchison 1-- __:-:.::;----~

s

Hokitika 2----

Martins Bay

' ' ' ' ' ''·Mandeville 1

Elgin 4 KEY 1 Personal ccllection Eiffelton 2 Museum collection Pleasant Point 3 Recorded in I i tera ture 4 Micromus not found.

Rg.31. Distribution of Micromus tasmaniae in the South Island JANUARY FEBRUARY

MARCH APRIL

MAY JUNE & JULY

X ~------~l ~ g 4 ~ 4 X X X X X X X Q~ ~------~~x~------~------~ A 00000000000000000 AJI~ N High I Gorse hedge. Pot a to patch. ~~ium JAphid numbers. Willow .trees . Absent Pine trees.

Fig. 32. Distribution of aphids in the chou moellier. JANUARY FEBRUARY

X

MARCH APRIL

0 0

~ 0 0 X 0 B 0 0 0 B 0 0 X 0 0

MAY JUNE

0 l 0 0 0 0 0 0 ® 0 0

0 0 ® 0 0 0 0

Anachris zealandica. Drepanacra bi nocu Ia. . . B onmya maorrca.

Fig. 33. Distribution of hemerobi ids in the chou moellier. 120

~I 100 II I I I I I I I I ,~~-\ ~ BO / II / \ r- 1 I / .L+·...... ,. I 60 / '~-, ,r·-·' }l. .• ~r -\ -..,..,~ La rvo I \, 1 I \ "1<,. .--- / ...... , I .X. \ )(' 1 I " >(. I •/ A I 40 1 y;' \ 7-. clu t J t~.' \, •• ...._, I X, I " \ I X_ I ' ' )< 20 '(____ '· --- ...... / JAN FEB HAR APR 20

15

10

5

MAY JUN JUL

10

5

--~-- AUG SEPT OCT 140 140

120

100

80

60

40

20

NOV DEC JAN 1964 Fig 34. Micromus tasmaniae population fluctuo- t ions 1 n the cabbage plots. 1 BO · 160 140 OF

GO

100 55

BO '-...... ------50 60 45

20

FE13 MAR APR 50

...... """ ... •, 45 •,' ....,._ ------20 40

~ 10 35

AUG SEPT OCT 35 2100 70 30 1800 65 2: 100 .,.------.... 60

55 50

45

NOV JA'l

Fig. 35. Relationship of M icromus tos man iae numbers and temperature. A Cabbage Plot. 160 1

130 .A .70

60 ..

•.

-o 50 :: --R:lras it i zed 0 QJ .: pupae. -o .. --Total imagines U) 40 ' and larvae. L dJ dead. .0 :--Dead pupae. ~ 30 z

20

10 : -·Deaths caused by spiders

F M A M J J A S 0 N D J 1963 1954 B

~pider pquaslid Drovvnd Ladybird Virus Wnknov.J Rlras'te TOTAL Adults 22 5 7 3 - 35 - 72 L.orva 4 1 1 6 - 7 1 2 - 67 Marked 7 1 - 1 - 1 9 - 28 RJpa - - - - - 199 25 2 4 51 70 7 1 3 4 7 265 252 618

Fig. 36. Micromus tasmaniae mortality A. Total monthly deaths observed. B. Analysis of deaths. 0

0

oo 0

I l l LPoint of releasing. 0 1 2 3 4 5 FEET

Fig. 37. Distribution of marked tl.icromus tasm.Jniae within Cabbage Plot l Dota for 1-4 shown in t::~ble6. 100 1963

90 80 ,., I \ I ' 70 II ' I ~ \ : \ I '•,., I\ , I I GO 50 1'/ \ ,'''....._, I I \ I I ,, I ;, I '; IV -,1 50 / \I f., I V I , 1 40 40 : v I I 30 !

\{) L NOV DEC 161 15100

~ 90 z so GO 70 r,·--''\./ I 60 50 .__ ,,1

50

40 40

30

20 30

10

JAN 30 ..... , ,'\ 551 'I __. '-' \ 20 , / \ ,/'Average tempemture 50 \ ,..... __, '/ between 7 & 12 pm. I /' 10 45 \/ Lacewings captured.

FEB MAR 1964 Flg.38. Relationship of lacewing numbers (attracted to I ight) and temperature. Locality, Homegarden. Fig.40. Micromus. tasmaniae flight times at Lineal n College. 1963-4.

5

9 1 1 13 15 17 14

Dec Jan

50 40 Ill ~30 ..a E 20 z,o:J

20 30 10 20 30 10 Dec Jan. Feb.

Fig.39. Lacewings caught by the Lincoln College I ight trap. 1963-4. spn--

hd-----

md-- Ventral ----spn

cp Fig. 41. Anachris zealand ica Top. Adult. Bottom left. Head of larva. Bottom right. Final larval instar. X 25

Fig 42. Hymen opterous pa.rasi te number 2 , adult. A Ventral B Dorsal. 2'-___.. (1)

--~--Gauze I I I I I I I I I I 1 I 2' \ I' ! I

'-·Sliding tin bottom.

0 0 0 0 0 ' ' ' ..... Ventilation and gas inlet.

+---- 5" ---+ Plastic hooks I I -2''-- '\ .... ,. ... ,,I ' .. ·• ·l r .....:)) ~.,, .,0? =~"'C) "\.:<::..._s~--x·u-...,_..,... ( 2) ·-----·Honey and ' (3) water store. ' 'Cot ton wool C.S. Lid Feeder ,Gauze / / _./... I I . I I --Walk-up. I .· . I

<------6 II--- Pupation Tube

t 1 " !

(4)

Fig .43. Equ i pll'}en t for mass rea r1 n g of Micromus tosmaniae...... ~ (/) ui (f) >.. >.. - z >.. a L ...__.. L Q) -a ::J :::J c ..0 E ..0 ~ L. 0 L (/) a a a (\) l.Dcality (\) ..c L <1.1 ~ +' +' c ~ u <1.1 +' a c a 0'1 c L 3 ::J a ..c -a a a 210 <( u u w u {:}. I

200

(/) 190 +' c ::J .r: 180 +' 0'1 c \ <1.1 170 0'1 c _.-Female. ~ 160

1 50 ...-Male / 140

Fig .44. M icromus tasmaniae. Geographic, sexua I and seasonal (Canterbury) variation in fore­ wing length. Spring Summer Autumn

/ ,.--\. / \ M icromus / \ / \ tasman· e // \ / \ / ,.. -+·.<. / i ": - ,( .>r ,L ~ :i ~ !- \- )(. " .t Aphids___ I /------.~· \- .}11. \.. -1 .ll' • )t..:}C ~--\ I .x -r \- /,/ -~.}11. ~ \ •.•.• ~ I // ,~· ~ \ ,/' •.•.•x >. I \ ,.,., .%;1( \ ...,....-' . .-•· ; I ___ ·"·- \,_,_ 0 N D J F M A M

Fig. 45. Diagr'amatic representot ion of th relative numbers of studied ects f rorr1 October to Apri I. 79

ACKNOWLEDG-EMENTS.

The research undertaken during the course of this thesis

was aided by many people whose help I gratefully acknowledge.

The many relations and friends who collected specimens

for me.

Dr. A. Harrison who made the Lincoln College insect traps

available and Miss M. Blackmore for her help in sorting specimens.

Dr. H. Smith of Crop ResearcD., Lincoln, Dr. J.M:. Kelsey

and Mr. A.D. Lowe of Entonology Division, Lincoln, for their advice

and help in the form of equipment.

Mr. E. Valentine of' Entomology Division, Nelson, for helping

in the identification of parasites.

Dr. T.E. Woodward of Brizbane University for insect

identifications.

Dr. T. C. Levds of Rothamstead Station, England, for supply­

ing information about hemerobiid flight times in that country.

The Botany Department of the University of Canterbury and

the Entomology Division at Lincoln who made thermostatically con­

trolled glasshouses available during winter.

Dr. A.D. Thomson of Plant Diseases Division, Lincoln, for

giving freely of his time and equipment for the isolation of the

virus.

Dr. R.A. Cumber of Plant Diseases Division, Auckland; the Auckland Museum, Dominion Museum, Camterbur,y Museum and :Bishop Museum so of Hawaii who all made their Micromus collections available to me.

Dr. V. Stout for many helpful discussions.

Professor Knox who permitted me to un6ertake all the research at my home.

Dr. R.L.C. Pilgrim for suggesting the topic and for supervising my preliminary studies.

The Technicians of the Zoology Department and especially

~o Mr. J. Darby for his enthusiastic help with the photography of this Thesis.

Mr. ani Mrs. A. H. :Nelson of Takapau, Hawkes Bay .whose

made it possible for me to collect lacewings from Hawkes

and Taranaki.

Mr. G. Hutcheon, of Lower Styx, upon whose prope~ty the chou moellier was grown.

Mr. T. Jessep of Entomology Division, Lincoln, whose assist~nce, advice and time was so readily , frequently at con- siderable personal inconvenience.

Mr. K.A.J. Wise of the Bishop :Museum for his helpful a.dvice, thoughtful criticisms· and support throughout the study.

Mr. J. Pollard of the Psychology Department of the

' University of Canterbury who helped with the statistics·.

Miss A.C. Nelson for proofreading, numerous suggestions and encouragement.

Dr. R.S. Bigelow, my supervisor, whose interest,advioe and construdtive criticisms were greatly appreciated.

My parents for permitting me to use a large sector of 81 their garden and allowing me to cultivate pest species in it. I thank them for their unfailing support and encouragement throughout all phases of the study. BIBLIOGRAPHY.

Abercrombie , W. Studies on cell number and the progression factpr in growth of the Jap:anese beetle larvae. J. of' Morphology. Vol 59. No.1.

Acker, T.S. 1960 The comparative morphology of the male terminalia of' Neuroptera (Insecta). Microentomology Vol 24. No.2. Pg.25-84.

Allee, W. c. , Emerson, A. E. , Park, T. , Schmidt, K. , 1949 Principles of' Animal Ecology.

Brues, C.T., Melander, A.L., Carpenter, F.Iv£. 1954. Classification of Insects.

Cottier, W. Aphids of' New Zealand D.S.I.R. Bulletin 103.

Cumber, R.A. , Eyles, A. C. 1961. Insects associated with the major fodder crops in the North Island. N.Z. J. agrio. Res 4 : 426-40.

Cumber, R.A. 1962. Insects associated with wheat, barley, and oat crops in the Rangi tikei, :Manawatu, Southern Hawkes Bay and Wairarapa:. Districts during the 1960-61 season • .N.Z. J. agric. Res. 5:163-78.

Hinton, H.E. 1957. Some aspects of diapause. Sc·i. Frog. No.178, April, F309-20.

1958. Concealed Phases in the metamorphosis of' insects. Sci. Frog. No.182, April, P260-75. 1960. The ways in which insects change colour. Sci. Prog. No.190, April, P342-50.

1960. A new classi~ication of insect p~pae. Proc. Zool. Soc. Vol 116 Pg. 282.

Hudson, G.V. 1904. New Zealand Neuroptera. London.

Hughes, R. D. 1960. Induction of diapause in Erioschia Brassicae Bouche. J. of Expt. Biol. Vol 59.

1962. A method for estim~ting the effects o~ mortality on aphid populations. J. Anim. Ecol. Vol 31, No.2, P 389-96.

Imms, A. D. 1957. A General Textbook of Entomology. Methuen. lullington, F.J. 1936. A Monograph of the British Neuroptera. Vol 1 and 2.

Kimmins, D.E., Wise, K.A.J. 1962 A record of Gryptoscenea Australiensis (Enderlein) in New Zealand, with a rediscription of the species. T.R.S.N.Z. Vol 88, No.4.

Lamb, K.P., Lowe, A.D. 1961. Studies of the Ecology of the cabbage aphid on brassica field crops in Canterbury, New Zealand. N.Z. J. agric. Res 4 : 619-42.

Lamb, K.P., 1961. Some effects o~ fluctuating temperatures on metabolism, development and rate of pnpulation growth in the cabbage aphid, Brevicor-.tne Brassicae. Ecology. Vol. 42, No.4, P740-5. Lowe, A. D. Role of aphids in spreading virus diseases. Proc. of 15th N.Z. Weed Control Conference P280-6.

Millar, D. 1956. Bibliography of New Zealand Entomology. D.S.I.R. Bulletin 120.

Nakahara, Yf. 1960 Systematic Studies on the Hemerobiidae. Mushi Vol. 34, Pt. 1.

Peterson, A. 1955 A manual of Entomological Tebhniques.

Rivers, C.F. 1957. Advances in Insect Virus Research. Proc. of Sth. Lond. Ent. and Nat. History Soc. 1956 P101-10.

Salmon, J.T. 1955. Notes on Staining Techniques for Polyvinyl Alcohol Mountants. The Microscope , 1 0 ( 6).

Snodgrass, R.E. 1935. Principles of Insect Morphology. McGraw Hill , New York.

1948. Facts and theories concerning the Insect Head. Smithsonian Misc. Coll. Vo1.122, No.9.

1954. Insect metamorphosis. Smithsonian Misc. Coll. Vol. 142, No.1.

Taylor, R.L. 1931. On '~Jar's Rule' and its application to sawfly larv1'te• Annals Ent. Soc. of ~. Vol.XXIV. P451-466.

Thomson, A.D. 1962. Photographic detection of zones after centri­ fugation in density-gradient columns of particles containing nucleic acid. Analytical Biochem, Vol. 4, No.1. P46-51. 85 Thomson, A.D., Reynolds, M.K. 1963. Puri~ication and electron

microscopy o~ carnation mottle virus. N. Z. J. agric. Res. Vol. 6, No.5, P394-408.

Tillyard, R.J. 1918. Studies o~ Australian Neuroptera. StuQy iv Family Hemerobiidae.

vii Li~e History o~ Psychopsidae elegans.

Proc. Lin.11. Soc.o~ N.s.vr.

1923. Descriptions o~ new species and

varieties o~ lacewings\ ~rom New Zealand belong­

ing to the ~amilies Berottidae and Hemerobiidae. T.R.S.N.Z. Vo1.54, P217.

Tjeder, B. 1961. Neuroptera Planipennia IV Hemerobiidae.

South A:tlrican Animal Li~e 1 Vol. VIII P296-408, 242 ~igs.

Tuxen, S.L. 1956. Taxonomtst's glossary o~ Genitalia in Insects.

Wiggleswortl,, V.B. 1953. The Principles of Insect Physiology. v;i thycombe, C.L. 1923. Notes on the tiology .of some British Neuroptera (Planipennia) Trans. Ent. Soc. London, P501-94.

1924. On some aspects of the Biology and Morphology of the Neuroptera. Trans. Ent. Soc. London, P303-418.

'.'tise, K.A.J. 1963. A List of the Neuroptera o~ New Zealand. Pacific Insects. 5 (1), P53-58.

Zimmerman, E.L. 1948. Insects of Hawaii. Vol.1. APPE...f\IDIX 1.

Lac.ewing numbers counted in the cabbages.

X Adult 0 Marked adult l Micromus ts.smaniae. p Pupa. L Larva J B Boriomya maorioa.

Date X 0 p L B Total.

29-1 36 1 5 42

30-1 38 2 7 1 48

2-2 53 2. 8 1 64- 1+-2 48 7 5 60 6-2 58 4- 15 77 8-2 53 1 16 70 10-2 55 9 4- 68 12-2 4-4- 10 9 63 1lJ.-2 21 6 8 35 16-2 34- 7 11 52 18-2 36 8 13 57 20-2 35 8 7 50 22-2 4-4- 3 40 87 1-3 27 8 35 70 3-3 25 5 34- 64 5-3 35 7 2 55 99 7-3 21 4- 1 69 95

10-3 31 4 1 109 14-4- 87

Date X 0 p L B TotaL

12-3 34 11 8 65 118 14-3 32 10 15 63 120 16-3 19 6 24 56 105 20-3 19 5 23 47 94 22',-.3 12 5 29 67 11} 24-3 19 3 37 66 125 28-3 9 3 58 83 15} 30-3 9 4 68 86 167 5-4 13 1 71 34 119 9-4. 15 3 67 37 122 13-4. 6 1 60 15 82 25-4 18 1 10 12 41 29-4 11 2 4 11 28 7-5 7 5 12 24. 11-5 14 6 7 27 31-5 12 10 7 29' 8-6 8 4 12 24 16-6 11 2 5 18

24-6 1 7 2 10 22-7 1 3 4 - 8 30-7 3 3 4 1 11 3-8 1 1 7 1 10

7-8 1 1 10 1 13 23-8 2 7 1 10 31-8 3 3 1 7

12-9 1 1 Date X 0 p L B Total.

16-9 1 1 20-9 0

28-9 0

6-10 1 1

10~10 1 1 2

18-10 1 1 22-10 2 2

26-10 3 3 6 30-10 2 2

3-11 4 2 6 7-11 2 1 3

11-11 13 3 16 15-11 8 2 10

19-11 1:; 4 17

23-11 15 7 22 27-11 16 1 9 26

1-12 34 1 6 41 5-12 46 7 53 9-12 40 3 23 66

13-12 55 6 35 96 17-12 96 5 3 53 158 21-12 112 5 5 99 221 25-12 108 5 20 117 250 29-12 192 1 28 164 2 387

2-1/64 179 3 57 165 404 6-1 183 86 201 470 89 Date. X 0 p L B Tota;l 10-1 24-4 111 259 614 14-1 310 1 106 387 4 834 18-1 279 1 177 405 4 865 22-1 290 217 392 2 901

26-1 379 1 266 515 10 1171 30-1 464 365 1252 19 2081

11 ,541+

APPENDIX 2.

Analysis of pupae counts in the cabbage.

p Normal pX Dead l 1

2 2

7-3 1 1

10-3 1 12-3 6 2 8 14-3) 15 15 16-3 16 8 24 20-3 19 4 23 22-3 18 2 9 29 24-3 19 6 12 37 28-3 33 13 2 10 58

30-3 4-4 11 1 12 68 90 __Date. p P'""C Ps p• Total 5-4 40 11 10 10 71

9-4 36 11 7 13 67 13-4 25 5 10 20 60

25-4 6 1 2 1 10

29-4 1 1 1 1 4 7-5 3 2 5 11-5 3 1 2 6 31-5 9 1 10 8-6 3 1 4 16-6 2 2 21!--6 7 7 22-7 3 3 30-7 4 4 3-8 7 7 7-8 8 2 10 23-8 7 7 31-8 3 3 ·22-10 1 1

9-12 3 3 13-12 5 1 6 17-12 3 3 21-12 5 5 25-12 20 20

29-12 26 4 27 2-1 54 3 57 6-1 63 20 3 86 94

Date. p r Ps p• Total 10-1 86 20 5 111 14-1 79 17 4 6 106 18-1 103 19 17 38 177 22-1 132: 26 17 42 217

26-1 133 28 42' 63 266

TotaJ.. 1053 199 126 252 .1§21.

APPENDIX 3.

Hemerobiids inha'oi ting fallen vegetation in the cabbage plots.

A Adult p Pupa I Micromus tasmaniae 1 Larva M Marked adult I Date. A p 1 M Total

14-3 1 5 11 17

16~3 2 20 12 34

20-3 4 2lf- 12: 40 22-3 1 19 8 28

24-3 1 31 lf- 36 28-3 2 47 13 62

30-3 1 46 13 60 5-4 60 2 62 9-4 1 50 4 55 13-4 1 43 1 1 46 25-4 2 6 1 9 92 Date. A p L M Total

29-4 4 3 3 10 7-5 2 1 2 5 11-5 2 1 3

8-6 1 1

24-6 1 1 2

7-8 1 1

10-10 1 1 2

22-10 2 2

26-10 3 3 7-11 1 1 23-11 2 2

27-11 3 3 1-12 4 3 7 2 18 4 22

9-12 12 3 9 24 13-12 6 2 9 17

17-12 18 3 29 50 21-12 38 5 75 118 25-12 95 19 61 175 29-12 35 27 141 203 2-1 63 56 144 2 265 6-1 114 81 176 371

10-1 155 111 250 516 14-1 183 106 387 1 677 18-1 151 177 358 1 689 22-1 170 217 342 729 Date. A p L M Total

26-1 225 265 457 1 956 30-1 226 265 716 1207

Total 1746 3130 6 6390

APPENDIX 4.

1964. Lower Styx Lacewing collections. ~maginesNormal l l ;: ~;::t (not usually collected) Pupa 1/.icromus 1 tasmaniae. P Parasitized by .Anachris zealandi[a J 2 P Parasitized by Hemiteles sp. J. Larva D Drepanacra binocula B Boriomya maorica. A. z. Anachris zealandica (adults) Rate :::: hemero'biids caut4d per minute. ~ ,.

Date Imagines P Px P 8 P 1 P2 Larva D B A. z. Rate 23-1 7 5 24-1 8 2-3 141 11 2 2 12-3 20 3 31 1 1 1.16 17-3 81 28 90 1 6 2 .66 23-3 22 63 6 13 80 1 2 1. 0 7-4 43 159 10 50 3 71 3 2 3 21-~- 213 29 4 1 66 5 1.5 25-4 72 16 2 4 12 .67 28-4 132 33 2 10 26 2 1.33 30-5 25 150 141 28 5 5 2.66 2-7 23 9 8 4 2 2 .4 25-8 2 28-9 94- APPENDIX 5.

M. tasmaniae counted in the rhubarb plot.

Date. Adults Unsexed Marked Larva Pupa

27-10 3 1 9

30-10 3 2 3 6

2-11 5 2 3 7

3-11 2 2 3 6 1

5-11 7 9 1 1

7-11 3 1 2 4

9-11 4- 3 3 9 11-11 4 4

15-11 9 10 3 2

19-11 8 11 3 4

23-11 18 19 3 3

27-11 13 12 2 13

1-12 14- 15 3 5 5

5-12 13 9 2 19

9-12 6 2 1 22

13-12 8 18 19

17-12 12 20 1 13

21-12 9 23 18

25-12 17 23 6

29-12 13 27 1 1

2-1 12 30 3 1

6-1 13 20 2 2 95 Adults Date. 9 0' Unsexed Marked Larva Pupa 10-1 23 4-3 20 10

14--1 22 31 12 6

18-1 21 25 13

22-1 10 26 3

Total. 275 387 59 37 192 2

952

.APPENDIX 6.

Light trapping results ~rom the home garden.

Date. Micromus tasmaniae. B. maori ca. Female Male. Unsexed Fernale Male Unsexed Total.

lp-11 1 4- 5

5-11 2 2 6-11

7-11 1 1

8-11

9-11

10-11 1 2 3 11-11

12-11 6 13 1 20 13-11

14--11 19 19 2 40 15-11 35 20 55

16-11 16 13 2 31

17-11 4 2 6

18-11 3 2 5 96 Mioromus t3smaniae. B. maori ca. Date. Total Female Me,le: Unsexed Female Male Unsexed

19-11 9 9 8 26

20-11 4 lt- 8

21-11 1 1

22-11 2 2

23-11 5 4 1 10

24-11 20 12 32

25-11 4 1 5

26-11 1 1

27-11

28-11

29-11

30-11 9 4 2 15

1-12 15 1 44

2-12 2 2 4

3-12 5 3 1 1 10

4-12 5 4 9

5-12 23 19 1 43

6-12 7 12 3 22

7-12 4 3 2 9

8-12 6 8 2 16

9-12 11 8 19

10-12 6 5 11

11-12 6 7 1 14

12-12 3 3 1 7

13-12 1 1

14-12 4 4 M. tasmaniae. B. maori ca. 97 Date. Female-Male Unsexed Female Male Unsexed Total.

15-12 1 1 2

16-12 12 5 17

17-12 4- 3 7

18-12 10 4 3 17 19-12 17 12 1 1 31

20-12 1 1

21-12 1 . 1 2 22-12

23-12 2 2 4

24-12 6 5 11

25-12 4 3 1 8 26-12 25 32 6 1 64

27-12 14 14 3 1 3 35

28-12 9 16 2 1 1 29 29-12 11 8 4 23

30-12 3 1 4- 8 31-12 45 4-5 2 1 93 1-1 28 32 7 67

2-1 5 4 1 2 2 14

3-1 9 8 2 1 1 1 22 4-1 5-1 6-1

7-1 28 37 7 72

8-1 21 19 3 5 48

9-1 73 85 3 3 4 1 169 9S M. tasmaniae. B. maori ca. Date. Total Female Male Unsexed Female Male Unsexed

10-1 17 13. 1 1 1 33 11-1 10 10 3 1 24

12-1 2 1 1 4

13-1 7 3 3 1 2 16 14-1 9 9 2 3 23 15-1 32 22 4 1 3 62

16-1 24 43 6 3 76 17-1 28 18 3 5 1 55

18-1 8 3 4 1 1 17 19-1 7 4 5 3 2 21 20-1 10 6 4 9 2 31 21-1 3 1 3 2 9

22-1 5 2 1 1 9

23-1 7 4 1 1 13 24-1 7 10 2 lj- 1 24

25-1 1 1

26-1 39 22 4 3 68 27-1 4 5 9

28-~ 3 3 6

29-1 3 4 1 8 30-1 3 3 6

21-2 5 8 1 14

22-2 1 2 . 3

23-2

24-2 3 1 4 00 .J ,/ :M. tasmaniae. B. maori ca. D~te. Total. Female Male Un;3execl Female :Male Unsexecl

25-2 1 1 2 26-2 2 2 27-2 2 2 4-

28-2 1 1 29-2 3 3 1-3 7 7

2-3 Lt- 1 5 3-3 1 1 4-3 2 4 6 5-3 5 1 1 7 Totals 850 738 97 74- 32 9 -1800

APPENDIX 7.

M. tasmaniae captured. by lights at Idncoln College.

1h_ .. maori ca. To':llal. Date Male Female Female Male 19-12 1 1 . 24/27-12 2 - 2 27/29-12 4 5 9 29/31-12 1 1 31-12/5-1 2 15 17 6/7-1 8 6 14- 8-1 2 2

9-1 1 7 1 9 10/12-1 1 1

14-1 1 _THE LIBRARY 1 UNIVERSITY OF CANTERBURY f"4R ISTC: HU~CH. N.Z. 100 DatE). Male Ji'ema1e Total J?cma,le Male

15-'1 6 4- 10

16~1 11, 12 26

17/19~1 1.1- 11- 8

20-1 6 1 8

21-1 L: 1 i 6

23-4 1

211/~6-1 23 ;22 !15

7/9-2 29 26 2 57

4 0/11,~2 2 1+- 6

1 L1/16-2 1 1

18-2 2 1 3

19-2 1

20-2 2 1,. 1 7

2-3 1 '1

Tota.1.s 108 122 ~L ')7·7 3 ~-~

THE UNIVERSITY OF CANTERBURY