The Biology of Zeius Remardii Kolenati Amd Zelus Socius Uhlee

The biology of Zelus renardii Kolenati and Zelus socius Uhler (Hemiptera: Reduviidae)

Item Type text; Thesis-Reproduction (electronic)

Authors El-Tom, Hassan Abbas, 1935-

Publisher The University of Arizona.

Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.

Download date 27/09/2021 17:27:37

Link to Item http://hdl.handle.net/10150/318453 THE BIOLOGY OF ZEIUS REMARDII KOLENATI AMD ZELUS SOCIUS UHLEE

(HEMIPTERA; EEDUVIIDAE)

Hassan A 0 El-Tom

A Thesis Submitted to the Faculty of the

DEPARTMENT OF ENTOMOLOGY

In Partial Fulfillment of the Requirements For the Degree of

MASTER OF SCIENCE

In the Graduate College

the: u n i v e r s i t y o f Ar i z o n a

19 6R STATEMENT BY AUTHOR

This thesis has been submitted in partial fulfillment of requirements for an advanced degree at The University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library0

Brief, quotations from this thesis are allowable without special permission^ provided that accurate acknowledgment of source is made@ Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his judgment the proposed use of the material is in the interests of scholarship^ In all other instancess however^ permission must be obtained from the authore

APPROVAL BY THESIS DIRECTOR

This thesis has been approved on the date shown below:

/S FLOYD Go WERNER Professor of Entomology AGKNOWIEDGiyCENTS

I am sincerely indebted to my thesis adviser5 Dr® Floyd

Ge Werner, Department of Entomology^ The University of Arizona, for his valuable guidance which facilitated the progress of this study®

I, also, extend my appreciation to all of the faculty and staff of the Department of Entomology, The University of

Arizona, for their many forms of assistance so freely extendedo

iii TABLE OF CONTENTS

Page

LIST OF TABLES * * . 0 0 0 © 0 0 o 0 © 0 0 © vi

ABSTRACT »ooeoo »ooe sfoo Q © 0 © 0 0 0 © * © a vii

INTRODUCTION o.oo. .°0 0 * 0 Q 0 0 0 0 0 1

MATERIALS AND METHODS a 0 0 © © 0 0 © © © 0 © 2

RESULTS AND DISCUSSION „ „ = o = 0 0 0 © 0 © 0 © 0 © 0 6 Zelus renardii Kolenati 'o o o 0 0 * 0 0 © © 0 © 0 6 Description of Stages 0 ® 6 O © 0 0 0 © 0 © e 6 Egg mass <> o » • o • o © O 0 0. 0 O © © © 0 © 6 Egg ©oeeooooe 0 O ©0 0 0 O©©0 ©© © 6 First instar nymph 0 o 0 O O 0 0 © © © 0 © © 0 7 Second instar nymph 0 Q © 0 0 O 0 © © © © © 0 8 Third instar nymph 0 c © O O 0 ©. © © © 0 © 0 0 8 Fourth instar nymph ® © © 0 0 O © © © © 0 © 0 9 Fifth instar nymph „ o © O 0 © O 0 0 © © O © 9 The adult 0 » o = » o 0 e 0 0 0 0 © ° 0 0 0 Cs 10 General Observations @ ® 0 Q 0 © Q 0 Q © © © © 0 0 11 Hatching process e 0 0 © @ 0 0 O O O a 0 0 © © 11 Molting process <, 0 0 © © o- © 0 0 0 0 0 e 12 Mating process o » ® e & 0 © a © 0 0 © 0 0 0 13 ■ Oviposition process o * 0 0 & © O © © © 0 © © 0 0 0 15 Host range => <, ® » , = O 0 © 0 © O 0 © . 0 © 0 0 0 © 16 Observations on feeding © © 0 O © * © 0 © O © 17 Cannibalism 0=000 0 000 © © 0© O © 19 Miscellaneous observations c © © © * 0 0 * © Q 0 21 Life Cycle © 0000000 0 0 0 0 0 © © 6 © 0 © © 22 Incubation period ® 0 0 © © e 00 © © 0 O 0 22 Duration of nymphal instars © © © © 0 0© © © 0 22 Premating and preoviposition period © 0 00 0 28

Fertility 0 0 0 0 = 0=0 * 0 0 © 0 © O © © © © 0 0 29 Fecundity 000 0 0 0 0 0 o 0 © 0 0 © © © © G 0 O 0 32

It V

TABLE OF CONTENTS— Continued

Page

Zelus socius Uhler o o *"* o e 0 9 0 33 Description of Stages » © 0 © 0 0 © 0 O O Ch 33 Egg mass 0 o o * * * © © 0 0 O 0 0 0 O O 0 0 33 Egg o O O O <5 O © O © 0 © 0 0 0 0 0 0 O 0 33 First instar nymph 6 © © © 0 0 0 0 O ©■ 0 0 O 3k Second instar nymph 0 0 © 0 0 0 O O 0 3k Third instar nymph * 0 © © 0 © 0 0 © 0 0 0 0 35 Fourth instar nymph 0 © © 0 0 0 0 O O 0 36 Fifth instar nymph 0 © © © © 9 0 © 0 0 9 © 0 36 The adult o o © o © 0 © 0 * 0 * 0 0 0 0 O 0 0 37

General Biological Observations © 0 © 0 0 0 0 ° 9 O 0 38

lafe Cycle o © o o e 0 o © © © © ©' . 0 0 0 0 0 0 0 UO

Fecundity 0 0 0 0 » » e © 0 0 ° 0 0 O °. 0 0 i|2

RATDR&L ENEMIES 0 * * * * . * * * © 0 © © 0 © 0 0 O 0 0 0 U3

Predators 0 © 0 0 © © © © 0 0 0 © © 0 0 0 0 0 a

Parasxtes © © © © © # © © & 0 © 0 0 © © O 0 Uit

SIIMMART © © © © © © © © 0 0 0© 0 0 © © © 0 © 0 0 O 0 U8

APPENDIX o©o©eoooo»oo © © 00 ©000 O 000 51

DITEBAIHRE CITED * * , © * * * , © © ©.0 0 0 O 0 0 38 LIST OF TABLES.

Page Table

1 Cannibalism in starved newly-hatched Zelus renardii nymphs © » ©© © » » © © © © © © ©.- ©- ■ © © © © © 20

2 Duration of the first instar of Zelus renardii in days © 23

3 Duration of the second instar of Zelus renardii in days S © © © O O OOO&OOO 0 ©©0 0 0 ©e6 0 0 0 © 2li

it Duration of the third instar of Zelus renardii in days © 2$

3 ■ Duration of the fourth instar of Zelus renardii in dayS ©oooo © o© o© oo ©©©ooo© ©oooo oe 26

6 Duration of the fifth instar of Zelus renardii in days © 27

7 The effect of timing of mating on the preoviposition period of Zelus renardii o © ©©©©©©©©©©©©©© 30

8 Duration of the instars, of Zelus socius in days o o © © i|l

9 Number of external eggs of Zelus renardii in relation to field infestation by Telenomus n© sp® parasite in August and September ^ 196k ©©*©©©©©©©©©©©«, kS

10 Some biological aspects of the parasite Telenomus n© sp © reared in laboratory from Zelus renardii egg masses during August and September, 196^ © © ©.©©©© I4.6

■ vi ABSTRACT

Zelus renardii Kolenati and Zeltts socins Uhler were reared in the laboratory*

The immature stages of both species have many characteristics in common but also have some striking differences® Some biological ob servations were made5 these were more or less the same in both speciese

The life cycle from the laying of eggs to the emergence of the adults varied from 27 to 63 days in Z0 renardii® and from 29 to U? days in

Zo sociuse The life cycle of Z® renardii from egg to egg varied from

35 to 78 days® The preoviposition period of Zc renardii was not af fected by the timing of mating® Repeated mating seemed to produce more fertilized eggs than one mating in this species® One Z0 renardii fe male laid 928 eggs in 18 massesj a field-collected Z® socius laid 58 eggs in three massese

A parasitej Telenomus n 0 sp0j, was reared from Z® renardii egg masses® The infestation was strictly limited to the marginal eggs of the masSo The. total life cycle of the parasite varied from 16 to 21 days®

vii INTRODUCTION

There has recently been a renewed interest in predaceous and parasitic insects as factors in the natural control of pest insects0

The present study is concerned with two species of predators <,

Zelus renardii Kolenati and Zelus socius Uhler are members of the hemipterous family Reduviidaes subfamily Harpactorinae o They are regarded as general predators on insects and may be quite abundant on crop plants @ No attempt has been made to evaluate them as predators in this study« The life cycle and immature stages have never been worked out in detailo These have been the principal subjects of this works

The number of generations per season and fecundity need to be deter mined before any field evaluation of their value can be made* Z0 ren ardii was easily reared in the laboratory., and many observations have been made on this species0 Z0 socius was not easy to rear, but enough observations could be made that a general comparison with Z0 renardii is possible* All stages of both species are described, so that they can be recognized in the fields One egg parasite was discovered and this species was also studied in a preliminary way@

1 MATERIALS AMD METHODS

Zelus renardii Kolenati and Zelus socius Hhler are. predators and require a daily supply of living prey insects 0 The individuals used in this study were kept in six-dram shell vials5 203 cme in diam eter s and provided with prey0 Leaf hoppers collected from bermudagrass with a sweeping net were used for a period® Both nymphs and adults were triede The genera Carneoeephala9 Draeculacephala5 Aeinopterusfl

Aceratagslli a.j and probably others were represented 0 A fresh branch of bermudagrass was placed inside the vial and leafhoppers of a size appropriate to the size of the reduviid were introduced by means of an aspirator® The bermudagrass dried so quickly that it did not maintain the leafhoppers for more than five hours# However^ Zelus renardii could be reared rather successfully on leafhoppers^ with 8 to !?0$ mor tality in the first instar and 0 to 5% in the other instars # This method was abandoned, chiefly because the leafhoppers varied greatly in abundance, and because the bermudagrass could not be swept when it was wet from rain or watering#

Aphids on the leaves of roses and oleanders were also tried for

Zelus renardii# A mortality of 70% in the first instar for rose aphids and 98% for oleander aphids indicated that aphids would not be satis factory prey insects# The very high mortality with oleander aphids may have been due to the presence of toxic substances in the aphids derived from the plant#

2 3

The prey finally used were adults of wild-type Drosophila mel anomas ter o These were reared on canned pumpkin in one-gallonwide mouthed jars5 and were inactivated by refrigeration for about one hour before they were introduced into the Z'elus vials e The actual transfer to the vial was made by using the Zelus vial as the specimen tube on an aspiratoro Carbon dioxide could have been used for the inactivation but was not used because it caused a distasteful acid reaction when in haled through the aspirator tubee The rearing vials were provided with a strip of toilet tissue in the nymphal rearings, or of hard paper for adults a This served as a foothold for both predator and prey, and as a site for the discharge of excrement <> casting of exuviae s and. oviposi- tion0 The method was adapted from that used by Balduf (1950) for rear ing Sinea diadema (Fabr*)« Both species of Zelus were reared success fully 5 with a mortality of from 3 to lk% in the first instar and 0 to

6$ in later instars e However,, the method proved not to be completely satisfactory for Zelus sociuss which was difficult to maintain in lab

oratory culture 0 Laboratory-reared houseflies were used for feeding adults in some caseso

In order to obtain egg parasites for study5 egg masses of Zelus renardil from the laboratory culture were placed around the campus of

the University of Arizona,, The eggs had been laid on hard paper strips^ which could be suspended by threads from trees and shrubs„ After they had had a chance to become infested,, they were placed in shell vials

and brought back to the laboratory for observations Adults reared from

these field-infested egg masses were introduced into other vials con

taining new egg masses from the laboratory cultures The procedure used was to place the vial containing parasites horizontally and mouth-to- mouth with the vial containing the new egg mass0 When sufficient num bers of parasites had moved to the new vial., it was closed with a piece

of uKleenexn facial tissues This procedure was necessary because the parasites did not respond to light, and because refrigeration seemed

to be detrimental to thems

The technique used for the study of the male genitalia is that described by Singh-Pruthi (1925)= The insect was first soaked in warm water and then placed in a 10% solution of potassium hydroxide for I4.8

hours, or until the tissues were soft and transparent# It was then transferred to $0% ethyl alcohol with a few drops of acetic acid to neutralize the potassium hydroxide in the specimen* Then the insect was stained with a small amount of piric acid in clove oil* The geni

talia drawings were made with a camera lucida*

Simple statistical methods were applied whenever it was appro^ priate# The mean (x) and the standard error of the mean (s-) were used

in recording many of the results* The mean value of the biological ob

servations, such as duration of instars, preoviposition period, incuba

tion period, number of eggs per mass, and number of days between one

egg mass and the next, was obtained by averaging these observations#

The standard error of the mean is an estimate of the true standard de

viation of the distribution of the sample mean# It was calculated by

following the equation s- * /si" , where s^ is • the variance and n is the x VT number of observations* The s^ was obtained from the equation where is summation and x is one observation. RESULTS AMD DISCUSSION

Zelus renardii Kolemti

Description of Stages

Egg masse The egg mass, is brown and usually arranged in a hex agon or pentagone It may consist of from 12 to 62 eggs® Swezey (1905) reports a range of from 19 to I4.0 eggs o The eggs are laid in regular transverse rowss which often consist of from h to 9 eggs5, but rarely as many as 10 or 11® The individual eggs are almost perpendicular to the substrate® Each egg is thinly covered with a sticky secretion so that it is well cementedto the others and to the substratee One or more of the sides of the egg mass is abundantly covered with the cementing se cretion©

Egg© The individual egg (Fig© l) is brown, faintly sculptured, and more or less barrel-shaped© Swezey (1905) reports it as cylindrical©

Its opening is covered by a conical operculum, whose base plane fits on to the opening© The operculum is enveloped by an extension of the chorion© The egg is browner on one side, which is slightly convex©

The rim of the opening in the egg (Fig© 5) is reticulated, with ellip tical whitish "seed-like" ornaments| the innermost part of the rim is black© The operculum (Fig© 3) is whitish and reticulated, with a de pression at the top3 its base plane is brown, the rim of the base and a spot in the center dark brown© The extension of the chorion is whitish, ivory-like, translucent, and slightly tilted toward the browner side of the egg3 it has a depression at the top® The dimensions of a measured egg were s- total length ls33 mm«j greatest diameter O0kk mm0 9 least

diameter5 below extension of chorion^ 0®33 iran0; diameter of opening left after hatching 0*36 mm0| diameter of base of operculum 0o33 mm0|. height of operculum 0ol8 mm0| diameter of extension of chorion 0o36 mno9 and height of extension of chorion 0o25 mme

First instar nymphe General color reddish brown, with a pale

line down the middle of the posterior lobe of the head and onto the pro- and mesothorax» Posterior lobe of head with three pairs of long

setaeo Meso- and metathorax dark at the loci of the wing buds= Abdo men with transverse uninterrupted red bands on the dorsal side, on all but the last two intersegmental membranes0 Black spots or black spines

are located at the sides of the intersegmental membranes of the dorsal

side as follows: black spots characteristically before segments 4 and

5, and black spines before segments 6, 7, and 8, these increasing in

length from front to backo Each abdominal spine bears a seta at its

apexo Antennae long and slender, and more or less dark in color; legs

also long and slender, and with black spots and many setae, especially

on the protibiae (Figo 7)o

The measurements of a typical specimen are as follows s body

length 2ol(. mme; width at meso thorax 0o5> mm0j greatest width of abdomen

0e6 mme| length of last two segments of the rostrum 0ok mm0; length of

spine before the eighth abdominal segment 0o2 mm0; length of the first

antennal segment I d mm0, second 0o$ mm<>, third 0o6 mm®, and fourth 0a8

mm® | length of profemur I d mm® and protibia 1*2 mm® Second instar nympho The second instar nymph (Fige 9) resembles

the first, except for a difference in size* But the posterior lobe of

the head has two pair of long setae and one pair short instead of three pairs long6 There is a lateral black spot in the intersegmental mem

brane before segments 2 and 3, and a spine before segments it through

8e The spines increase in length from front to rear, as in the first

instar, but they are present on two additional segments and do not bear

setae on their apices#

The measurements of a typical specimen are as follows s body

length 3«7 mmoj width at mesothorax 0o6 mm0, greatest width of abdomen

I d mm0| length of last two segments of the rostrum 0@7 mm0 j length of

spine before the eighth abdominal segment 0e3 mme| length of first an

tenna! segment 1@3 mm«, second 0a6 mm0, third 1*1 mm», and fourth 0*8

nrniB | length of profemur 1@3 mm* and protibia le8 mm®

Third instar nymph® The third instar nymph (Fig® 11) resembles

the second, except for a difference in size® But the posterior lobe of

the head has no setae® The anterolateral angles of the prothorax pro

trude sharply® Hesothoracic wing pads partly overlap the metathoracic

pads® Black spines are present before segments 2 through 8® The spines

are therefore present on two additional segments® They increase in

length from front to rear, as in the earlier instars, but the spines be

fore segments 7 and 8 are equal in length® The legs are conspicuously

spotted®

The measurements of a typical specimen are as follows: body

length 3®0 mm®| width at mesothorax 0®8 mnuj greatest width ofabdomen loll, iron05 length of last two segments of the rostrum loO mm0| length of

spine before the eighth abdominal segment O0I4. mm*; length of first an

tenna! segment 2*0 mmoS second le0 mmo3 third 1*5 mm* and fourth 1*0 mm*; length of profemur 2 *0 mm* and protibia 2*0 mm*

Fourth instar nymph* The fourth instar nymph (Fig* 13) resem bles the thirdj, except for a size difference* But the mesothoracic wing pads completely overlap the metathoracic pads and reach about to

the middle of the first abdominal segment* There is a sharp triangular projection on the anterior margin of each wing pad*

The measurements of a typical specimen are as follows t body

length 3*6 mm*; width at me so thorax 1®3 mm*; greatest width of abdomen

1*7 mm»; length of last two segments of the rostrum 1*1 mm*; length of

spine before the eighth abdominal segment 0*6 mm*; length of first an

tenna! segment 2*8 mmo3 second 0*8 mm*s third 2*2 mm*-> and fourth 1*1

mm*; length of profemur 3®0 mm* and protibia 3*0 mm*

Fifth instar nymph* The fifth instar nymph (Fig* 13) resembles

the fourth^, except for a difference in size* The general color is red

dish brown* as in the case of the previous instars * Kirkaldy (1907)

describes it as pale green, and Swezey (1905) as light-bluish green®

The meso- and metathoracic wing pads reach the end of the second abdom

inal segment® The spine before segment 8 is shorter than 'the one before

segment 7*

The measurements of a typical specimen are as follows: body

length 8*3 mm®; width at mesothorax 1*7 mm*; greatest width of abdomen

2*0 mm*; length of last two segments of the rostrum 1*7 mm®; length of 10

spine before the eighth abdominal segment 0oU mma| length of first an-

tennal segment 3o3 mmej) second 0S8 rnmas third 3®3 mmes and fourth 1*0 mm0j length of profemur 3o3 mm® and protibia i|.*2 mme

The adult® General color rufouss with a pale longitudinal

line down the middle of the posterior lobe of the head and onto the prothorax® The anterior lobe of the prothorax has a reticulate pattern

of pale markings| the posterior lobe is darker, not reticulated| the

antero- and posterolateral angles are more or less pointed® The corium

is rufous to darker with pale veins | the membrane is uniformly dark, with slightly darker veins 0 The dorsum of the abdomen is rufous and

lacks the lateral spines and red bands of the nymphs® The underside of

the abdomen is pale® The antennae are long and slender® The legs are

long, slender, and not spotted, with many setae, especially on the pro

tibiae® The middle legs are shorter than the others ®

The measurements of a typical female and a male, respectively,

are as follows2 body length li|.oO, U ®3 mm®5 width at mesothorax 3«0,

2 o5 mm® j greatest width of abdomen 3e0, 2®5 mm®j length of last two

segments of the rostrum 2®3, 2®3 mm®5 length of first antennal segment

lj.<60, I4.0O mm®, second 1®5, 1®0 mm®, third j^oO, i|.e0 mm®, and fourth 1®0,

1®0 mm® 3 length of profemur 3=0, li®0 mm® and protibia 3®5, 4®0 mm®

The male genitalia (Fig® 17) consist essentially of a median

tubular organ, the aedeagus, which is a backward continuation of the body wall between the ninth and tenth sternites® The aedeagus is dif

ferentially ehitinized® In the condition of repose, the distal region

of the aedeagus is retracted into the proximal portion® The proximal 11 portion is called the phallosoznas and the distal portion the endosoma0

The "Reduviid type" endosoma is not differentiated into a conjunctiva and a vesica (Singh-PruthL, 1925) = The phallosoma bears at its proximal - end a pair of lateral-appendages which are called parameres e The parameres are rod-like, blunt at the apices, and hairy® The diameter of the blunt apex is 0#23 mm0 A slender, vertical, hooked process (spine) extends apically from the ninth sternum; the length of the spine with out the hooked part is Q&Q7 mm®

General Observations

Hatching process® Beadio (192?) reports that the hatching process has been witnessed for several species of Reduviidae but not for all® The cap of the egg is gradually lifted by the pressure exert ed by the nympho The nymph gradually works its way out of the egg, en veloped at first in a membrane which binds the appendages close to the body® Eventually the body, which is usually bent double in the egg, is

straightened out; and the legs, antennae, and beak are freed from the membrane by repeated pullsQ

The first instar nymph of Z0 renardii pushes open the operculum, which then lies on edge near the egg opening= The pushing is done by

the prothorax, while the head is strongly bent downwarde After the

operculum has been pushed aside, the nymph slowly forces its way out of

the egg openingo During the process, the legs, antennae, and beak are pressed to the ventral side of the body® The body is moved back and

forth and the legs are bent inward and relaxed at the tibiae just below the articulation of the femora and tibiae® One egg takes from 5 to 10 12 minutes to hatch, and the eggs in a whole mass hatch in from ij, to 7 hours® The general color of the hatching nymph is yellowisha

The hatching nymphs have a definite orientation in the egg masso Nymphs hatching from the part of the mass proximal to the fe male during oviposition are more or less positively oriented to the female| nymphs from the distal half are more or less negatively ori ented, and those from the middle are either positively or negatively orientedo This orientation is related to the darkened side of the egge Hatching nymphs always orient toward the darkened side* The eggs are also darkened at one side in the brood sac of the female, whether fertilized or not® This indicates that the embryo does not cause this darkening, which is predetermined before fertilization takes placeo There is no relation between orientation and sex of the off spring 0

Molting process* At the start of molting, the nymph stays in one places The head is strongly bent down® Then the exuviae are pushed slowly over the thoracic area and the abdomen0 During this process, legs and antennae are pressed to the ventral side of the ab domen 5 the body is moved back and forth, and the legs bent inward and relaxed at the tibiae just below the articulation of the femora and tibiaeo When the exuviae reach the last abdominal segments, the ap pendages are pulled out* The middle legs come out first, then the front and hind legs together, and finally the antennae0 The exuviae remain a while at the tip of the abdomen0 13

Molting takes from 5 to 10 minutes, "but the molt to the adult stage sometimes takes more than 10 minutes® The general color of the molting stages is greenish®

Mating process® Readio (1927) reports that certain features of the mating habits seemed to be uniform throughout the members of

Reduviidae® The male mounts, holding to the female with his legs® He usually supports himself further by applying the tip of the rostrum to the juncture of the head and thorax® During this time the female head bobs up and down, and a sharp ear will detect a faint chirping® The chirping results from the rubbing of the tip of the rostrum on the trans'

Tersely ridged longitudinal groove of the prostemum® Copulation may last for many hours® However, the position assumed by the males of some species may vary somewhat®

The male of 2® renardli approaches the female from any direc tion and often the pair start to fight® The male mounts sideways® He holds onto the dorsal side of the abdomen of the female with his three left or right legs, while the middle leg of the opposite side usually

clutches the ventral side of the body® The tip of his abdomen is ex tended along the underside of the female abdomen until it reaches her

genital organs® The male strikes his rostrum repeatedly on the fe male's neck, and sometimes there is a short interval during which his rostrum is kept raised up® During the whole time, the female keeps her beak raised, possibly for threat and warning® Both sexes may walk together for a short distance® The female sometimes feeds on a prey insect during mating® After 30 to k$ minutes the female rejects the lit male5 apparently by moving her body so that the male cannot cling to her back no matter how aggressive his endeavors e One male was seen trying to copulate with a female while she was laying eggs, but he was rejectedo The male can mate repeatedly with the same or different females o One male was observed to mate with a female six times (includ ing twice on successive days) during a period of three weeksG There fore, the female does not reject repeated mating during her lifetime, but does reject the prolongation of one mating and mating during ovi- positiono On the basis that the female is capable of rejecting the males, it could be inferred that the raising of the beak during mating and the small fight before and after mating serve as warning and threat, and not unwillingness c

All Reduviidae are said to possess the cross-striation in the longitudinal groove of the prosternum that permits stridulation

(Usinger, 19ij.3)o Readio (1927) reports that the ridges in the groove are functional in the nymphs and adults of all the American species which he examined@ However, Kirkaldy (1907) describes the fifth in star of Z0 renardii as having an unstriated sulcate prosternuma The writer examined the nymphs and adults of 2* renardii and was unable to identify any cross-striation of the groove 0 In no case was the insect observed to stridulate0 During mating, the female keeps her beak raised* This is unlike the behavior reported by Readio (1927), in which the females of Reduviidae perform chirping during the processe

Therefore, the raising of the female’s beak during mating is apparently related to the lack or feeble development of the cross-striation in the longitudinal prosternal groove* 15

Oviposition process0 The female starts touching several places on the substrate with the setae of the tip of the abdomen0 Then she assumes the egg-laying position,, usually after from 5 to 10 minutes*

After that and until the last egg is laid, the legs are kept wide apart from the body and most often they do not move from their places* The anterior and middle legs are elevated in such a way that the tip of the abdomen is slightly above the laying site* Thus, the female assumes an approximate ii.50 orientation* Then she lays the first egg* Before lay ing the second egg she starts touching different places of the laying

site, including the laid egg (or eggs), with the setae of the tip of the

abdomen* The second egg is laid adjacent to the first egg, and the pro

cess is repeated until the first row is completed* The first egg laid may not necessarily be the marginal one of the first row, because the next eggs may be laid in such a way that the first egg ends up in the middle* Similarly, the eggs of the next rows are laid anywhere in the

intervals and in contact with the eggs of the preceding rows* One row may be longer or shorter than the others, so that the egg mass assumes

a geometrical shape* Bach egg is thinly covered with a sticky secre

tion, so that the eggs in a mass are well cemented to each other and to

the substrate* After depositing the last egg, the female secretes the

sticky substance abundantly, as she gives the final touches to one or

all of the external rows of the egg mass* The laying of the whole egg mass takes from 1 to 2 hours* The transverse rows of the'egg mass vary

from Ij. to 9 eggs, rarely as many as 10 or 11* In the latter cases it was observed that there is a slight disarrangement* In laying rows of 16 more than 9 eggs5 the female must move her legs to a new position and

this apparently disturbs the orderly arrangemente

Host rangeo Morrill (1910) reports the adults ate Chlorochroa

ligata nymphs in confinements Horton (I9l8a5 -b) records that the

young nymphs fed on first and second instar Scirtothrips citri nymphs

and mealybugse Swezey (1936) records a list of prey insects consisting

of 13 species of Hymenoptera5 6 Dipteras it, Coleopteras and 7 Hemipteras

Among thems 13 species were distinctly beneficial«, Ewing and Ivy (I9ii3)

record that nymphs and adults preyed on bollwora eggs* The newly

hatched larvae did not reach the second instar in the presence of the

predators o Clancy (I9it5) found the predator would not feed on Euschis-

tus impictiventris eggs and motionless nymphs but would take the moving

nymphs6 Hishida (1935) gives a list of prey insects including the

sugarcane leafhoppers and eoccinellid beetles0 Mielson and Henderson C (1959) record Therioaphis maculata as a prey0

Laboratory rearing of all stages of the predator was carried

out with Drosophila melanogaster and with leafhoppers swept from ber-

mudagrass as preys The genera of the leafhoppers were Oarneocephala*

Draeculacephala 9 Acinopterus 9 Aceratagalia and probably others * The

adult predators were sometimes given a meal of houseflieso Although

aphids on the leaves of roses and oleander were taken by the predatorss

they caused a high mortality0 The predator in.confinement attacked

lygus sppo5 larvae of Colias eurytheme s Macrosiphum pisi* a species of

Meloidae and young grasshopper nymphs 0 But it did not attack Habis 17 sppog Geocoris spp05 adults of Hippodaroia convergens (contrary to

Nishidag 1955)5 and fleabeetles swept from beraudagrasse

The predator preferred moving prey* This is in agreement with the observations of Clancy (I9it5) o When inactivated Drosophila or houseflies were introduced to the containers^ the predator did not feed unless the prey had become active e Also, dead prey was not utilizeda

Aphids on leaves of roses and oleander were not satisfactory prey in

sects e The predator nymphs seemed to take no notice of the motionless living aphidso Howevers under conditions of starvation or when the majority of the aphids were motionless^ the nymphs indiscriminately in serted their beaks into motionless living aphids as well as into the leaf tissue«, So it was inferred that thenymphs or adults became starved when the prey was motionless®

The predator seemed to have no preference with respect to size

of moving prey insects» An adult in confinement did not discriminate between 5 houseflies and 20 Drosophila® It killed 2 of the former and

12 of the latter in one day®

Observations on feeding® Readio (1927) describes the feeding habits of the subfamily Harpactorinae® These insects possess a strong

curved beak and front and middle legs fitted for grasping and holding

the prey® The insects take their position in a situation likely to be

frequented by other insects5 such as flower heads? leaves9 and twigs®

The predator awaits the approach of an insect to the vicinity and then maneuvers in such a way that the prey will approach within grasping

distance? or stalks the insect slowly and cautiously® At the final . 18 moment of attack^ the insect is grasped by the sticky front legs and pierced by the stylets of the beak at the same instant* The poisonous saliva is then injected into the prey until it stops struggling*

Zelus renardii captures the prey with the front legs, and the beak is inserted into the prey at the same instant® Then the middle legs may assist the front legs in grasping large-sized prey* Usually after a Drosophila is captured, the predator uses neither the front legs nor the middle 0 The middle legs also assist the front legs in changing the feeding site, irrespective of the size of the prey*

Readio (192?) states that "at the insertion of the reduviid stylets, the sides of the labium at its apex contract and hold the sty lets firmly so that they may be inserted through the exoskeleton of the prey®“

The predator prefers certain feeding sites® laboratory obser vations are consistent with Readio's (1927)® The feeding sites are located at the intersegmental membranes, pleural sutures, cervix, and compound eyes®

Attempts were made to determine the number of prey killed per day by the predator® The adults completely sucked out from 1 to 5 houseflies, which were then very shrunk® Sucked-out Drosophila prey for the first and second instar nymphs were not recorded® The third instar nymphs completely sucked out an average of 3®53 Drosophila per day, with a range of from 0 to 12 j the fourth, if.=9 3 with a range of from 0 to 17J and the fifth, l5®00 with a range of from 3 to 33® The completely sucked-out Drosophila were characterized by their transpar ent bodies, which could be detected under the binocular microscope. J

19 as noted by Balduf (1990)= Howevers it was quite difficult to deter- j mine the number of killed prey5 especially for the early instar nymphs <, which did not suck out most prey completelyQ

Cannibalism0 Morrill (1910) and Swezey (1936) claim that Zelus renardii is unconditionally a cannibalistic inseeto Experiments sum marized in Table 1 show that starved^ crowded nymphs are cannibalistic» but that fed, crowded nymphs are not# The thirteen starved individual nymphs lived as long as four days e The twenty starved, crowded nymphs became cannibalistic by the fourth day, so that some of them lived as long as seven days# Meanwhile, the thirteen fed, crowded nymphs showed

competition instead of cannibalism, because the development of four nymphs of the first instar was conspicuously retarded# This retarded development more than likely resulted in the non-cannibalistic death

of these four nymphs of the first instar® At eight days of age there were four nymphs in the second instar and four in the third instar0

These eight nymphs were reared together to the fourth instar# During

this stage they were starved for one day and then given 60 newly hatched nymphs# Only two cases of cannibalism were seen on that days

a fourth instar nymph was sucking out a nymph of the first instar, and

a fourth instar nymph was sucking out a fourth instar nymph while the latter was in the molting process 0

To sum up the results, cannibalism is natural under conditions

of severe starvation# In nymphs of the same age, the strong attacks

the weak or an equal rival while it is molting or otherwise incapaci™

tatedo TABLE le— Cannibalism in starved newly-hatched Zelus renardii nymphs

Starved Starved individual Crowded Crowded nymphs fed 50+ Drosophila per day nymphs nymphs

Alive Dead Date Alive Dead Alive Dead First Second Third First Second Third instar instar instar instar instar instar

7-15 13 - 20 - 13 - - -- -

7-16 13 - 20 - 13 --- - -

7-17 13 - 20 - 12 - - la - -

7-18 13 - 9 11 5 6 - 1 - -

7-19 - 13 6 3 2 7 - 2 --

7-20 — - 5 1 1 8 - - - -

7-21 -- i k - 8 — 1 - -

7-22 - — 1 - k h -- -

aLost

ro o 21

Miscellaneous observations„ Geographical distribution$ The

genus Zelus is strictly Americano Z8 renardii is recorded from Calif

ornia^, Kansas5 Texass and Mexico (Keadibs 1927)o It was introduced

into the Hawaiian Islands prior to 1897 (Swezey* 1905)e In Arizona

Werner and Butler (1957) report that it is fairly well represented in

samples from the southern countieso Pinal County had the highest num ber, followed by Pima and Maricopa,, The highest number was recorded

from samples taken in the fall and winter* followed by those from

spring and summer,, The insect does not hibernate in southern Arizona* where winters are raildo

Humber of generations % One generation per year is recorded for

the members of the family in most eases (Readio* 1927) o During the

present study and under laboratory conditions * two generations of Z@

renardii were reared in the summer of 1961|.0

Sex ratios There seems to be a 50:50 ratio of sexeso The lab

oratory rearings produced $6 females and 6l males»

Placement of egg masses; The eggs of the members of the family

are usually found in the same places as the adults and nymphs (Readio*

1927)o One Z0 renardii egg mass was found on the upper surface of an

oak tree leaf (Sabino Canyon) and another on the upper surface of a

citrus leaf (Tucson)6 This may indicate that the insect prefers to lay

eggs on the upper surface of a broad* smooth firm leaf0

Gleaning procedure; Z 0 renardii fed on aphids cleaned honeydew

from their antennae« The cleaning is achieved by pulling the antennae

through a slit made by placing the front tarsi together in front of

the bodyo 22

life Cycle

Incubation period0 The incubation period of the eggs in the laboratory was 708k & Oell days, within a range of 7 to 9 days for 25

egg masseso However> the incubation period was different for the egg masses which were placed in the field and brought to the laboratory two to five days before hatching0 In this case the period was 7©28 * O0II4. days5 within a range of 6 to 9 days for 1*2 egg masses® Swezey (1905)

reports it as ranging from 8 to 10 days®

Duration of nymphal instars« Records were kept of the duration

of the nymphal instars under laboratory conditions® The times are shown

in Tables 2 through 6 ®

The lowest and highest means of the first instar were 5«3l* and

8®10 days® The total range of all the means was from 1* to 11 days®

Swezey (1905) found that this instar took 5 days© The lowest and high- ( est means of the second instar were 1*©17 and I*®65 days© The total

range was from 3 to 7 days© Swezey (1905) reports it as 5 days© Simi

larly., the third instar means were lj.o00 and I*e86s and the total range was from 3 to 7 days© Swezey (1905) found it to be from 5 to 8 days©

The minimum and maximum means of the fourth instar were and 6®50

days® The total range was from 1* to 9 days® Swezey (1905) reports

it as from 5 to 7 days© The fifth instar means were 6©90 and 1 2 083

and the total range from 6 to 20 days® Swezey (1905) reports it as

9 days®

The fifth instar was relatively the longest® Moreover,, the

fifth instar of the Angust-September rearing extended to as long as 23

TABLE 2.— Duration of the first instar of Zelus renardii in days.

Prey Egg Standard mass Date Number Range Mean per day error No* Per nymph

1 6/17-6/28 11 7-11 8.10 0.80 10-15 Lb

2 6/19-6/29 17 6-10 7,Wi 0.23 7-15 L

3 6/23-6/30 2U U-7 5.U6 0.16 10-25 L

h 7/6 -7/12 29 5-6 5.3L 0.09 20-30 D

5 7/9 -7/17 30 5-8 6.23 0.16 20-30 D

6 7/27-8/lt 36 5-8 6.28 0 .1U 30-1,0 D

^L * Leafhoppers; D - Drosophila*

^First two days nymphs were fed with aphids living on roses* TABLE 3.— Duration of the second instar of Zelus renardii in days*

Prey Egg Standard per day mass Date Number Range Mean No. error Per nymph

1 6 /2 4 -7 /2 10 3-7 U.Uo 0*34 10-20 L

2 6 /2 5 -7 /2 IS 3-7 I4.60 0.26 10-20 L

3 6/2 7-7 /U 23 U-S U.17 0.08 10-2S L

k 7 /1 1 -7 /1 8 28 U-7 U.So 0.13 20-30 D

$ 7/1U -7/21 2 S U-S 0.10 15-20 D

6 8/1 -8 /9 3U 3-S 0.09 30-40 D

^L * leafhoppers 5 D ■ Drosophila* 25

TABLE It,— Duration of the third instar of Zelus renardii in days#

Prey Egg Standard per day mass Date Number Range Mean per No# error nympha

1 6/28-7/6 10 3-5 U#oo 0.15 10-20 L

2 6/30-7/9 Hi U-6 U.78 0.19 10-25 L

3 7/2 -7/10 21 U-7 li#86 0.18 10-25 L

h 7/15-7/22 28 U-5 U.61 0.09 20-30 L

5 7/18-7/27 2U U-6 4.75 0.11 15-20 D

6 8/6 -8/13 31* U-5 4.76 0.07 30-40 D

^L * leafhoppers; D * Drosophila# 26

TABLE jp.— Duration of the fourth instar of Zelus renardii in days.

Prey Egg Standard per day mass Date Number Range Mean error per No. nymph

1 7/1 -7/12 10 2*-6 4.70 0.22 10-20 L

2 7/U -7/13 13 U~5> 4.54 0.14 10-25 L

3 7/6 -7/16 18 5-7 5.5o 0.09 10-25 L

h 7/19-7/28 28 5—6 5.82 0.07 20-30 D

S 7/23-8/3 23 5-7 5.83 0.14 15-20 D

6 8/10-8/20 3ii 5-9 6.5o 0.16 30-40 D

*L • leafhoppers; D * Drosophila. 27

TABLE 6•— Duration of the fifth instar of Zelus renardii in days#

Prey Egg Standard per day mass Date Number Range Mean error No# Per nymph

1 7/5 -7/19 10 6-7 6.90 0,10 10-20 L

2 7/8 -7/21 12 7-8 7.25 0.13 1S-2S L

3 7/11-7/21+ 16 7-10 7.86 0.18 10-29 L

h 7/25-8/8 26 8-12 9.38 0.18 20-30 D

$ 7/28-8/13 23 8-13 9.70 0 .2U 19-20 D

6 8/16-9/7 30 9-20 12.83 0.66 30-1*0 D

aL * leafhoppers; D * Drosophila# 20 dayss with a high percentage of sterility (27%) and crippling (lj.3%) in the adult stage „ The temperature was then 1°F to 2°F lower than the 78°F which had been prevailing from June to the middle of August®

Thereforej, the fifth instar seems to be more sensitive to temperature than the otherso

Premating and preoviposition periods 0 Most paired newly-emerged females and males mated when they were about 2lj. hours old® Males which were 2k hours old or more mated with any females whether hardened^ ten- eral5 or sterile0 Some teneral females were paired with hardened males 6

The males immediately copulated with the female So After mating was ac complished* they were separatedo These mated females were as able to lay fertilized eggs as any mated hardened femalese The hardening or tanning process was apparently completed by 10 hours after molting0 Therefore * the age of the unhardened females was less than 10 hoursa On the other hand* the males were unable to mate with any female until they were 2It hours old* or lit hours after hardening was apparently complete« This was perhaps due to the relatively slow hardening of the genital organs <,

Therefore* the age of the male was the determining factor of the pre mating period* which was one day after molting to the adult stageo The unhardened female is sexually mature* and this is probably true for the teneral male®

The average preoviposition period was 9@00 ± O0I4O days for 23 fertilized females0 The range was from 7 to lit days® 29

Fertility

When the females are inseminated^ fertilization takes place and the eggs laid are viable 0 Some aspects of fertility«, such as the ef fects of timing and times of mating were studied,,

When mating takes place at any time during the normal preoviposition period (from 7 to llj. days)s the female usually deposits her first fertilized egg mass within the lit. days0 This is shown in Table 7o Fe males Nose 1 through 10 laid their first egg masses ls 6S 6, 7fl 7 5 ks 8S ls 1, and lit days after the date of pairing0 Their ages.at the time of pairing were 7, 15 1, 15 0, 11, 1, 10, 8, and 0 days, respectively® As explained by.Snodgrass (193S>5 pp« 5>6l, 566), the insemination of the eggs is not generally accomplished in most insects during the act of mating, but takes a varying length of time afterwardse Most female in sects are provided with a sperm receptacle in wbich the spematazoa are storedo The speraatazoa are ejected upon the eggs as the latter are ex truded from the oviduct® Then the eggs are usually deposited at once®

Therefore, mating at any time during the preoviposition period would not change the duration of the preoviposition period® In the case of females 36 days old or older, the first fertilized egg masses were laid after it to 7 days from the date of pairing, as shown in females Nos® 11 through 1 3 o

Repeated mating seemed to produce more fertilized eggs than one mating® One female was observed in coition four times, on July 27, Aug ust ij., August 8 , and August 1 0 ® The male was removed after the August

10 mating® This female laid 18 egg masses, totalling 928 eggs, during her lifetime, from July 13 to September 17o The eighteenth egg mass TABLE 7.— The effect of timing of mating on the preoviposition period of Zelus renardii.

Days between Age in Date of Date when Date Days between Total female emerg No. of Date of days first female first pairing and ence and lay egg Remarks pairing when mating was egg mass laying of masses female ing of first paired (seen) separated laid first egg mass laid egg mass

1 7/18 7 7/18 7/19 7/19 1 8 1 died 2 7/16 1 a 7/22 7/22 6 7 7 died 3 7/20 1 a 7/26 7/26 6 7 11 died b 7/20 a 7/26 7/27 7 8 8 died 5 7/21 a 7/26 7/28 7 7 11 died 6 8/3 11 8/3 8/3 8/7 U 15 11 died 7 8/3 1 8/3 8/3 8/11 8 9 21 died 8 8/15 10 8/15 8/15 8/16 1 11 17 died 9 8/15 8. 8/15 8/15 8/16 1 9 10 killed 10 8/26 0b 8/26 8/26 9/9 lit 14 1 killed 11 8/26 U2 a 8/30 8/30 U 46 1 killed 12 8/26 36 a 9/2 9/2 7 43 3 killed 13 8/26 Uo a 9/2 9/2 7 47 3 killed

^Probably mating occurred more than once, but those without footnote a mated only once, for from 30 to minutes*

^Age of the females was less than 2k hours. 31

(22 eggs) did not Hatch and showed no indication of development of em bryos o A once-mated female (No* 7) laid 21 egg masses5 totalling 831 eggs, during her lifetime, from August 2 to November 3o The eggs in masses 15 to 21 , totalling 262 eggs, did not hatch and showed no indica tion of development of embryos* Similarly, another once-mated female

No* 8 ) laid 17 egg masses, totalling 663 eggs, during her lifetime, from August 5 to October 19» The eggs in masses lit to 17, totalling

1)|)| eggs, did not hatch* To sum up the results, repeated mating seemed to produce more fertilized eggs (906 out of 928) than one mating (589 out of 851 and 519 out of 663 eggs)* It is logical to assume that more than enough of the spermatazoa were ejected from the spermatheca onto the ova* Therefore, repeated mating was a necessity for fertilization of the late ova, corresponding to the late egg masses*

During the study, ll|. sterile females were encountered, espec ially in the late rearing in August and September* Sterility was in dicated by the shrinkage of the abdomen* The abdomen of a gravid fe male (fertilized or unfertilized) was distinctly swollen after six days from emergence * One sterile female that had been mated failed to produce eggs during her lifetime of 30 days* One male with disabled

genitalia was encountered* He had a permanently protruding aedeagus

from the time he molted to the adult stage* He tried to mate like normal males, but his aedeagus failed to meet the female’s genital

organs *

Some unfertilized, gravid females were not paired with males

during their lifetimes® They laid irregular egg masses or none* The eggs did not hatch, but were similar in shape, color, and size to fertilized eggs® The mean number of unfertilized eggs per mass was

2 3 o00 ± 6 0385 with a range of from 3 to 62 eggs for eleven observa tions o The preovipdsition period was 2lj.ol!.2 ± 3o01 days3 with a range of from 13 to 36 days# for seven females® The maximum number of egg masses laid by one unmated female was three®

The time interval between laying egg masses of some of these unmated females varied from 2 to 22 days*

Fecundity

Fecundity is indicated by the number of eggs produced by the female during her lifetime® The fecundity of Zelus renardii is greater in the case of mated females® A female that mated several times laid

18 egg masses totalling 928 eggs# and a "once-mated female laid 21 egg masses totalling 851 eggs® Most females laid from 8 to 16 egg masses3 some of these females died and some were killed® Swezey (1905) reports that a field-collected female laid 8 egg masses totalling 269 eggs®

The mean number of eggs per mass of 30 mated females was lt0®95»

± 1®90# for 272 observations® The range was from 12 to 62 eggs®

Swezey (1905) reports it as from 19 to ij.0 eggs®

The mean time interval between the laying of egg masses by a . mated female was 3®86 ± 0o133 for 2lj2 observations on 28 females® The range was from 1 to lit days® A three-day interval had the highest fre quency (106 observations)® Swezey (1905) reports the time interval as

an average of 5 days# with a range of from 2 to 9 days# for seven obser vations o o

33 Longevity: One female lived for 92 dayss and one male for I4.8 days 0

Zelus sooins Uhler

Description of Stages

Egg masSo The egg mass is dark brown and may consist of from

11 to I4.0 eggs 0 That of Zelns renardii may have as many as 62 0 The transverse rows contain from 3 to 6 eggs; in Z0 renardii they contain from I|. to 11 o The mass is usually arranged in a pentagon^ quadrangles

or irregular circle^ while that of Z0 renardii is usually in a pentagon or hexagon0 Readio (1927) described the mass as elongate0 The individ ual eggs are laid almost perpendicularly and are thinly covered with a sticky secretion,, as in Ze renardii0 The sticky secretion covering one

or more sides of the egg mass is less abundant than in Z® renardii®

Egge The egg (Fig® 2) is more or less similar to that of Zelus

renardii3 except for some minor differences» It is.dark brown and con spicuously sculptured, whereas the egg of Ze renardii is paler brown

and only faintly sculptured® The rim of the opening in the egg (Fig® 6 )

is entirely black and not reticulated, while that of Zc renardii is

reticulated,with elliptical whitish "seed-like1* ornaments» The oper

culum (Fig® 5) is hemispherical instead of conical® The base plane of

the operculum is dark brown, the rim of the base black and a spot in

the center paler brown® In Z„ renardii, the base plane is brown, the

rim of the base and the spot in the center dark brown® The extension

of the chorion is cream-colored rather than white, and more strongly

tilted toward the darker side of the egg® The dimensions of a measured egg were: total length le55 mme|

greatest diameter Oeiilj. mm0| least diameter below extension of chorion

Oo33 mm6| diameter of opening left after hatching 0 o35> mm0| diameter of base of operculum 0o33 mm8| height of operculum 0 013 mm©! diameter of

extension of chorion Oe35 mmos and height of extension of chorion 0o27 mm© Readio (1926) gives the total length as 1©70 mm©

First instar nympho The first instar nymph (Fig© 8) has many

characteristics in common with that of Zelus renardii© Some differ

ences are: general color greenish instead of reddish brown© Posterior

lobe of head with two short setae instead of three long setae© Abdomen without red bands® Black spots on knobs, instead of black spots and

spines, are similarly located at the jsides of the intersegmental mem

branes of the dorsal side of the abdomen© A spot on a knob is located

before segments b through 8, and these increase in size from front to

rear© The legs are not spotted©

The measurements of a typical specimen are as follows: body

length 2©2 mm©, width at mesothorax Ooij. mm©; greatest width of abdomen

0o6 mm©| length of last two segments of the rostrum 0oij. mm©; length of

the head lacks setae, while the first instar nymph has two pairs of

has two pairs of long setae and one pair of short setae© The abdomen lacks red bands0 The spots on knobs on the abdomen do not Increase in number from the first instar® The legs are faintly spotted®

The measurements of a typical specimen are as follows z body length 3 o3 mm0| width at mesothorax 0o6 m o -5greatest width of abdomen

0 o7 ram®3 length of last two segments of the rostrum 0 o7 mm0| length of

first antenna! segment 1 ®5> nrnio$ second 0 o6 mm® ^ third I d mm e9 and fourth 0o-9 mmo| length of profemur loS mm 0 and protibia lo5> mm®

Third instar nympho The third instar nymph (Fig® 12) resembles the second£ except for a difference in size* But the anterolateral angles of the prothorax are sharply protruding, though not as sharply as in the third instar nymph of Zelus renardii® The mesothoracic wing pads partly overlap the metathoracic pads® There are interrupted red transverse bands and longitudinal red stripes on the dorsal side of the abdomen® These are not present in the previous instars0 The red bands in Z 0 renardii are continuous and transverse, and also present in the early ±nstars0 Black spots on knobs are located laterally be fore segments 2 through 8® The spots and the knobs increase in size from front to rear, as in the second instar, but are present on two additional segments®

The measurements of a typical specimen are as follows: body length 5=0 mm® i width at mesothorax 0 o9 mm® 3 greatest width of abdomen leO mm ®3 length of last two segments of the rostrum 1®0 mm ®3 length of first antennal segment 2®5 mm®, second 0®5 mm®, third 1®5 mm®, and fourth loO mm ®3 length of profemur 2®2 mm® and protibia 2®2 mm® 36

Fourth instar nympho The fourth instar nymph (Figo lli.) resem bles the third, except for a difference in size0 The general color is greenish; but with many darker markings 0 The mesothoracic wing pads almost completely overlap the metathoracic pads and reach the anterior border of the first abdominal segments In Zelus remardii, the wing pads reach about to the middle of the first abdominal segments There are no triangular projections on the anterior margins of the wing pads o

The measurements of a typical specimen are as follows: body length 7q2 ram0| width at mesothorax loO mm0j greatest width of abdomen lol mme| length of last two segments of the rostrum leli. mm0| length of first antennal segment 3 o3 mm«; second 0 o8 mmaj) third 2@8 mm0s and fourth 1S1 mmoj length ofz profemur 3 o3 mm0 and pro tibia 3o0 mm®

Fifth instar nympho The fifth instar nymph (Fig® 16) resembles the fourth; except for a size difference® The meso- and metathoracic wing pads reach the middle of the second abdominal segment® In the fifth instar of Zelus renardii they reach the end of the second abdom inal segment® Readio (1927) describes them as reaching the middle of the third abdominal segment®

The measurements of a typical specimen are as follows t body length 12®7 mm®| width of mesothorax 1®7 mm®5 greatest width of abdomen

1®7 mm®| length of last two segments of the rostrum 1®7 mm®j length of first antennal segment 5®0 mm®5 second 1®7 mm®; third ^®6 mm®, and fourth lo3 mm®| length of profemur 5>®0 and protibia 5®0 mm® The adulto General color dark* In Zelms renardii the adult

color is rufouso Paler specimens have a pale longitudinal line down

the middle of both lobes of the head^, and sometimes onto the posterior

lobe of the prothoraacj this line becomes darker on the anterior lobe

of the prothorax * However^ darker specimens have a pale longitudinal

line only on the posterior lobe of the head* The anterior lobe of the prothoirax often has a feeble pattern of paler markings <> while the adult

of Z0 renardii has a well-defined reticulate pattern of pale markings|

the anterolateral angles are not as sharply protruding as in the adult

of Z» renardiio The posterior lobe of the prothorax has the postero

lateral angles spined and,, in addition, has a pair of spines on the disc

just behind a line connecting the lateral spines 0 Z0 renardii has no

spines on the disc of the posterior lobe of the prothorax* The corium

of the hemelytra is dark, with pale veins* The membrane is uniformly

dusky, with darker veins* The dorsum of the abdomen is dark rufous to

dark rufous blended with black, and lacks the black spots on knobs and

the red bands of the nymphs® The underside of the abdomen is pale®

The antennae are long and slender® The legs are long, slender, and

faintly spotted, with many setae, especially on the protibiae® The

middle legs are shorter than the others®

The measurements of a typical female and a male, respectively,

are as follows: body length l£05, 12®5 mm®| width at mesothorax 2 ®5,

2®0 mm®| greatest width of abdomen 2 ®!?, 2®0 mm®j length of last two

segments of the rostrum 2 ®3, 2®3 mm®5 length of first antennal segment

5 ®5>, 5*3 mm®, second 2 ®0 , 2*0 mm®, third 5>®3, f>«,0 mm®, and fourth 1 ®5,

1*5 mm® | length of profemur 6 *0 , 3*0 mm* and protibia 6 *3 , 6 e0 mm* The male genitalia (Fig® 18) resemble those of Z® renardii but show some differences® The parameres are rod-likes blunt at the apices^ and hairy® The diameter of the blunt apex is 0o13 mm0jl which is less than in Za renardii6 in which it is 0*23 mm* A shorty acutefl triangu lar spine extends apically from the ninth sternum® The length of the spine is 0ol3 mm0j, which is shorter than in Z* renardiiQ in which it is

0*87 mm* long®

General Biological Observations

Many biological observations on Zelus socius are more or less similar to those for Zelus renardii*

The hatching^ molting; and oviposition processes are similar in both species® The egg mass of Z* socius takes about k hours or less to hatch; while in Z0 renardii the time varies from it to 7 hours* The gen eral color of the molting stages is green.; while in Zc renardii it is paler* The oviposition process takes about one hour or less in Z0 socius, and the transverse rows of the egg mass vary from 3 to 6 eggss while in

Z» renardii the process takes from 1 to 2 hours,, and the transverse rows vary from it to 11 eggs®

The host range of Z* socius has been little studied® Knowlton

(1932) observed the species feeding on Oiroulifer tenellus in the lab oratory® Eeadio (1927) reared a fifth instar nymph to the adult stage on houseflies® During this study all nymphal stages and adults were reared on Drosophila melanogaster adults* Sometimes the adult stage was fed with houseflies and Lygus spp® As in the case of Z* renardii® the predator preferred moving prey® 39

Feeding sites were typically the same as in Zelus rehardiia

Attempts were made to determine the number of Drosophila prey killed per day by the predators The first instar nymphs completely sacked out an average of 0e03 Drosophila per day, with a range of from 0 to ls the second 0 ol5 with a range of from 0 to 1 ; the third 2 o03s with a range of from 0 to the fourth 6 0139 with a range of from 0 to 17$ and the fifth 5 <>5>5 with a range of from 3 to 10e The third instar nymph of Z0 renardii completely sucked out an average of 3»53 Drosophila per day, with a range of from 0 to 1 2 j the fourth k°93g with a range of from 0 to 175 and the fifth l^*Og with a range of from 3 to 33=

The genus Zelus is strictly Americano The geographical distri bution of Z0 socius extends farther north than that of Z0 renardiig

Zo socius is found from Florida to California^ north to New England and the Dakotas (Blatchley, 1926 and Readio, 1927)o 3h Arizona Werner and Butler (1957) report that it was fairly well represented in samples from the southern countieso Pinal County had the highest percentage, followed by Pima and Marieopae It was best represented in spring samples, followed by those from fall, summer, and winter, while Z0 ren ardii was best represented in the fall and winter samples, followed by spring and summer#

During the present study, from June to September, only one gen eration was reared# The first rearing in June and July produced 6 fe males and 10 males, of which 2 and 5, respectively, were cripplede The second rearing, in August and September, produced only 3 females out of

19 individuals, and the rest were unable to complete molting® Life Cycle

The incubation period of the eggs and the duration of the five nymphal instars were studiede The premating and preoviposition period were not studied because the insects failed to mate*

The laboratory incubation period was 7<$75 * 0*25 days for four egg masses* The range was from 7 to 8 days* In Z0 renardii„ the range was from 7 to 9 days® The lengths of the nymphal instars are shown in Table 8* The means for the first instar were 6®75 and 6*21 dayss and the total range from 5 to 8 days® The range of Z® renardii first instar was from if. to 11 days® The means of the second instar were 3®7k and 5®085 and the total range from 3 to 6 days® The range of the second instar of Z® renardii was from 3 to 7 days® The means of the third instar were 3®83 and 5®17 days® The total range was from 3 to 6 dayss while that of Z® renardii was from 3 to 7 days® The means of the fourth instar were kok7 and 6 ®k6 days5, and the range was from k to 7 days® ' The Z® renardii fourth instar was from k to 9 days® The means of the fifth instar were 7®k3 and 10®k7 days® The total range was from 7 to 12 days? whereas that of Z® renardii was from 6 to 20 days® leadio (1927) reared a field-collected fifth instar nymph in

Julys and after 8 days it emerged to the. adult stage® The August-

September rearing extended the fifth instar# as in the case of Z® ren ardii 0 The life cycle from the laying of the eggs to the emergence of the adult varied from 29 to k7 dayss while in Z® renardii it varied from 27 to 63 days ® la

TABLE 8.— Duration of the instars of Zelus socius in days*

Drosophila Egg Standard provided mass Date Number Range Mean error per day No* per nymph

First instar 1 6/18-6/26 20 6-8 6.75 0.11* 10-20 2 8/21-8/29 21* 5-8 6.21 0.15 10-20

Second instar 1 6/2U-6/29 19 > u 3.71* 0.10 10-25 2 8/26-9/2 2U li-6 5.08 0.08 35-50

Third instar

1 6/27-7/3 18 3-U 3.83 0.09 20-30 2 8/31-9/8 21* l*-6 5.17 0.10 35-50

Fourth instar 1 7/1 -7/18 17 li-5 1*.1*7 0.12 30-1*0 2 9/h -9/15 21* 6-7 6.1*6 0.10 1*5-55

Fifth instar

1 7/6 -7AS 16 7-9 7.1*3 0.16 30-1*5 2 9/11-9/2S 19 9-12 10.1*7 0.21 5o-6o k2

Fectmdity

A field-collected female laid three fertilized egg masses of 115

305 and 17 eggss respectively0 The time interval between the laying of egg masses was 7 and 3 days 5 respectively0 The female might have laid some egg masses before its capturee laboratory conditions were prob ably unfavorable for continued laying» The mean number of eggs per mass was 26*33 t 1l031 for 6 egg masses laid by.four field-collected females*

The range was from 11 to I4.0 eggs* Eeadio (1927) collected an egg mass consisting of 22 eggs* A gravid unfertilized female lived for about

I4O dayss and a field-collected male for about 30 days*

/ ! NATURAL. ENEMIES

Predators

There is only one recorded predator of Zelus in the literatures

Smith (1923) found Zelus nymphs in the nest of Bicyrtes quadrifaciatus s a wasp of the family Sphecidae, subfamily Nyssoninae5 and tribe Bembi- cinio During the course of the present studys an ant which was acci dently introduced killed a second instar nymph of Zelus renardii, probably in self-defense, but possibly as a predators

Parasites

Muesebeck (195)1) cites Hadronotus leptocorisae (family Sceli- onidae) as a parasite of Zelus bilobus, with a reference to Hubbard

(1883) | but the latter had bred this parasite from the eggs of Lepto- corisa tipuloides (family Goriscidae)0 Ashmead (1886) reared Eupeimus zeli (now Anastatus zeli) from the eggs of Zelus longipese This wasp, of the chalcidoid family Eupelmidae, was not encountered in the present study6

However, an egg parasite was discovered,, This is a wasp of the family Scelionidae and subfamily Telenominae, identified by C„ F e Wo

Muesebeck (196i|., personal communication) as Telenomus n® sp0 The par asites were reared from egg masses of Zelus renardii Kolenatio Approx imately 200 egg masses of Zelus renardii were placed on trees on the campus of the University of Arizona during August and September, 196)40

The egg masses were on narrow strips of paper, where they had been U3 bh laid by females in captivity® The strips were suspended from trees by strings® Four of these egg masses were parasitized by Telenomus, as

shown in Table 9® In general,, only the outer rows of eggs were parasi tized® The only exception occurred when an egg in an inner row was ex posed because of a gap in the outer, row® The number of infested eggs is limited by the number exposed at the edges (from about 15 to 2k eggs in an egg mass) ® In the four egg masses parasitized in the field* 30% (6 out of 2 0 ) to 86% (19 out of 2 2 ) of the marginal eggs were infested®

A life cycle from 19 to 20 days was indicated for the wasp from the field studies* but there was no way of determining when the wasp had found the egg masses® Therefore* a series of laboratory rearings was attempted during the same period® In these* adult parasites were

introduced into vials containing egg masses of Zelus renardii® for which the age was known within 2k hours® The parasites were left for

2k hours and then removed® The results are shown in Table 1 0 ® The on set of the parasite pupation appeared after lit to 16 days from the time

of the introduction of the parasites® Pupation took five days® The

total life cycle varied from l6 to 21 days®

Symptoms of parasitization usually appear after U to 5 days

from the time of the introduction of the parasites* as a whitish inclu

sion* to the fleshy whitish larva® The larva grows bigger and bigger*

until it nearly fills the Zelus egg® Five days before emergence of the

adult parasite* the egg is characterized by a metallic black or blue

color* due to the coloration of the wasp pupa® k5

TABLE 9*— Number of external eggs of Zelus renardii in relation to field infestation by Telenomus n. sp. parasite in August and September, 1961*.

No. of No. of No. of Days from time Serial external infested parasites eggs were put out No. eggs external eggs emerging to emergence

1 22 19 19 20

2 18 1U 12 19 2 20

3 2U 12 12 19

h 20 6 2 19 2 20 TABLE 10e— Some biological aspects of the parasite, Telenomus n* sp., reared from Zelus renardii egg masses in the laboratory during August and September, 1961;•

Life cycle No. of No. of Date of No. of Date of No. of No. of from time of infested Serial parasites adult external No. pupation pupae adults infestation external introduced emergence eggs (days) eggs

1 3 a a 9/2 1 16 15 Hi 9/8 11 17 9/9 1 18

2 6 a a 9/8 12 17 19 19 9/9 7 18

3 3 a a 9/25 3 17 20 3

h 6 9/22 15 9/27 15 19 19 17 9/23 1 9/28 1 20 9/21* 1 9/29 l 21

5 7 9/22 9/27 6 19 a a 9/23 9/28 1 20

^Not recorded*

^A pupa inside a partially exposed egg in the second row because of a gap in the outer row* 1*7

After the emergence of the parasite* the egg was characterized by an exit-hole at its distal third near the egg cape This exist-hole was pushed out by the thorax of the parasite* SWMMLY

Zelus re.nard.ii Kolenati and Zeius socins Uhler are predators

on insectso They were reared under laboratory conditions on Drosophila

adultse Z0 renardii was also reared on leafhoppers swept from bermuda-

grasso

The egg masses of Zo renardii are brown and contain from 12 to

62 eggs | those of Z0 socius are darker brown and contain from 11 to lj.0

eggSe The eggs of both species are barrel-shaped but have minor dif

ferences o There are five nymphal instars in both species» Nymphs of

Z0 renardii are generally reddish brown with lateral spines on the dor

sal side of the abdomen5 nymphs of Ze socius are generally greenish with knobs instead of spines© The male genitalia of Z0 renardii have

larger parameres than those of Z» socius» The former has a slender

hooked spine5 and the latter an acute triangular spine5 at the apex

The hatching process is the same in both species,, with the

nymphs oriented toward the darker side of the egg* Both species are

similar in the molting and oviposition processes = The act of mating

in Za renardii is typical of the Reduviidae5 except that the female

keeps her beak raised instead of chirping0 This may be related to the

lack or feeble development of the cross-striations of the prostemal

Drosophila are completely sucked out by late instar nymphs than by the k9 younger nymphs© The nyirphs of Z0 renard.il are cannibalistic under con ditions of severe starvatione

The genus Zelus is strictly American5 Z0 socius extends farther north than Z0 renardii© Neither species hibernates in southern Arizona, where winters are mild© Two generations of Z© renardii and one genera tion of Zo socius were reared in the laboratory during one season© The sex ratio of Z© renardii seems to be a normal 50s5>0 ratio© In nature

The laboratory incubation period of Z© renardii egg masses was from 7 to 9 days5 that of Z© socius from 7 to 8 days© The length of the first instar of 2 © renardii was from ij. to 11 days, and that of Z© socius from 5 to 8 days© The second instar of Z© renardii lasted from 3 to 7 days, and that of Z@ socius from 3 to 6 days © The third instar of Z© renardii ranged from 3 to 7 days; that of Z© socius from 3 to 6 days©

7 days, respectively© The fifth instar of 2© renardii was from 6 to 20 days, while that of 2© socius was from 7 to 12 days© The premating per iod of Z© renardii males was one day© The preoviposit!on period of Z© renardii was from 7 to lit days; that of Z© socius was not recorded©

Therefore, the life cycle from the laying of eggs to the emergence of the adults was from 27 to 63 and from 29 to lf.7 days, for Z© renardii and

Z0 renardii females mated at any time during the preoviposition period lay their first fertilised egg masses most often within the limits of the preoviposition period0 Repeated mating in Z0 renardii seemed to produce more fertilized eggs than one mating<, Sterile fe males were encounteredo Unfertilized eggs did not hatche

One Z0 renardii female laid 928 eggs in 18 massesj, and one field-collected Z0 soclus laid 5>8 eggs in 3 masseso The mean number of eggs per mass was l|.Oo55 and 26<>33s for Ze renardii and Za socius, re spectively, The time interval between the laying of egg masses by a female varied from 1 to lit days for Z» renardii and from 3 to 7 days for Z0 socius0 One ZG renardii female lived for 92 days and one male for I4.8 days^ while one Z» socius female lived for about UO days and a

■ - / field-collected male for about 30 days,

A parasite5 Telenomus n, sp,, was reared from Z, renardii egg masseso The number of parasitized eggs is strictly limited by the num ber exposed at the edges of the egg masse The parasite pupated from lit to 16 days after infestation of the eggs* The pupation period was

5 days. The pupation of the parasites in many egg masses was not re corded, but the total life cycle was recorded. The total life cycle of the parasite varied from 16 to 21 days. a p p e n d i x ; Figure 1. Zelus renardii. egg. (X56)

Figure 2. Zelus socius, egg. (X56)

Figure 3. Zelus renardii, operculum of the egg. (X$6 )

Figure Zelus renardii, rim of the opening of the egg after hatching.(X5o)

Figure Zelus socius, operculum of the egg. (X£6)

Figure 6 . Zelus socius, rim of the opening of the egg after hatching. T w ) 51

5 o6 Figure 7» Zelus renardii, first instar nymph. (X26)

Figure 8. Zelus socius, first instar nymph. (X28)

Figure 9» Zelus renardii, second instar nymph* (XI?)

Figure 10* Zelus socius, second instar nymph* (X19)

Figure 11# Zelus renardii, third instar nymph. (X13)

Figure 12, Zelus socius, third instar nymph# (X22) 5h Figure 13. Zelus renardii, fourth instar nymph. (Xll)

Figure 3J4. Zelus socius, fourth instar nynph. (X8) 55

I 4 Figure If?, Zelus renardii, fifth instar nymph.

Figure 16, Zelus socius, fifth instar nymph. 56 Figure 17. Zelus renardii, lateral view of male genitalia. TnfT

Figure 18. Zelus socius, lateral view of male genitalia. T H ? y

Terminology: a * endosoma, b * phallosoma, c * paramere,

d * spine, e * ninth abdominal sternum. 57

b d

18 LITERATURE CITED

Ashmeadj, ¥ 0 H a 1886» S'tudies on the North American Chalcididae with descriptions of new species from Florida@ Trans0 Ame Entomolo Soce 135l25-135«

Balduf5 Vo V. 19!?0o Utilization of food by S'inea diadema (Fabre)® Anno Entomolo Soc0 Amer# 1|.3» 331|.-360o

Blatchley-j, W 0 So 1926® Heteroptera of Eastern North America,, Nature Pub® Co,, Indianapolise 1116 p 0

Clancy, D 6 Vo 19^6* Natural enemies of some Arizona cotton insects e Jo Econo Entomolo 39s326-328 ®

Ewing, K 0 Po and E® E» Ivy® 19U3® Some factors influencing bollworm populations and damage® J® Econ® Entomol® 36:602-606®

Horton, Jc R 0 1918a® The citrus thrips, U® S® Dep® Agr® Bull® 6l6 ® 1|2 p®

® 1918b® The Argentine ant in relation to citrus groves® Ue S® Dep® Agr® Bull® 6^7 ® 7k p®

Hubbard, H® G® 1889® Insects affecting the orange® U® S® Dep® Agr®, Div® Entomol® 227 p®

Kirkaldy, G® V® 1907® Biological notes on the Hemiptera of the Hawai ian Isles® Proc® Hawaiian Entomol® Soc® 1 (U)sl35-l6lo

Knowlton, G® ¥® 1932® The beet leafhopper in Northern Utah® Utah Agr® Exp® Sta® Bull® 23i+o 6h p®

Morrill, A® ¥® 1910® Plant bugs injurious to cotton bolls® U®S® Dep® Agr® Bur® Entomol® Bull® 8 6 ® 110 p®

Muesebeck, 0 ® F® ¥®, et a!® 1951® Hymenoptera of America North of Mexico® Synoptic Catalog® U® S® Dep® Agr® Agr® Monog® ,2® 11*20 p®

Muesebeck, C® F® ¥® 1961|.o Personal communication®

Nielson, M® ¥® and J® A® Henderson® 1959® Biology of Collops vitta- tus (Say) in Arizona and feeding habits of seven predators of the spotted alfalfa aphid® J® Econ® Entomol® 52s159-162® 5 9

Nishidas Ts 1955o Natural enemies of the melon fly Dacus curcurbitae CoqttJ> in Hawaiio Ann* Entomol* S'oc* Amer* ^8:171-178*

ReadiOg P* A* 1926* Studies of the eggs of some of Reduviidae* Univ* Kansas Sci* Bull* l6;l57~179o

______1927 e Studies on the biology of the Reduviidae of Amer ica North of Mexico* Univ* Kansas Sci* Bull* 17:5-291*

Singh-Pruthif H* 1925= The morphology of the male genitalia in Rhyn- chota* Trans* Entomol. Soc* Londoni 127-26?j, pi® 6-32*

SmithM* R* 1923= The life history and habits of Bicyrtes quadri- fasciata Say (Hymenoptera: Bembicidae)0 Ann* Entomol* Soc* Amer* 16:238-2^6*

Snodgrass5 R* E* 1935* Principles of insect morphology* McGraw-Hill Book Coo5 New York and London* 667 p*

Swezey5 0* H* 1905* Leafhoppers and their natural enemies* Hawaiian Sugar Planters1 Assoc® Exp* Staos Div* Entomol*s Bull* 1(7):

212 - 238 * . -

______* 1936* Biological control of the sugar cane leafhopper in Hawaii* Hawaiian Sugar PlantersT Assoc* Exp* Sta*s Entomol* Ser*j, Bull* 21:57-101*

Hsinger, R* L* 19l|3$ A revised classification of the Reduvioidea with a new subfamily from South America* Ann* Entomol* Soc* Amer* 36:602-6189

Werners F* G* and G* D* Butler^ Jr* 1957* The Reduviids and Nabids associated with Arizona crops* Arizona Agr* Exp* Sta* Tech* Bull* 133* 12 p 0