BIOLOGY AND HABITS OF THE RUST , ROSAE (FAB.), IN OREGON (DI1'rERAz )

by

CARL ROBERT TANNER

A THESIS

ubmitted to

(1EGON STATE COLLEGE

in partial fulfillment of the requirement a for the degree of

MASTER UF SCIENCE

June 1951 APPROVED s Redacted for privacy

Head of Department of Entomology In Charge of Major Redacted for privacy

Chairman of School Graduate Co.itt.. Redacted for privacy

Dean of Graduate School

Date thesis is presented May 11, 1951

Typed by Ruth V. Newcomer ACKNOWLEDGLENTS

The writer wiihes to expreas his sincere thanks to Dr.

D. C. ote, head of the Department of Entomology at Oregon State

College, and Mr. H. E. Morrison, of the Oregon State Experiment

Station, for making this work possible, and for their helpful suggestions in the preparation of this thesis.

To Dr. C. H. Martin, Associate Professor at Oregon State

College and Dr. W. J. Chamberlin, Associate Professor at Oregon

Stato College, the writer is indebted for their suggestions and criticisms. Also, to Dr. H. H. Crowell and Mr. R. W. Lauderdale, both of the Oregon State Experiment Station, the writer expresses sincere appreciation for their help and suggestions.

To Mr. John Garman of the Physics Department at Oregon

State College, the writer extends thanks for his excellent photographic work.

To the many others who have offered suggestions and advice, the author is indebted. TABLE OF CONTENTS

Page

Introduction...... i

Economic Importance...... i

History and Distribution...... 2 Host P]ants...... 5

sature of Injury...... 8

SynonynyandDesoriptionoftheSpecies...... II

Descripti of the Egg...... 12

Deoiption of the Larva...... 12

Decripti of' the Pupa...... 15 DesoriptionoftheAdult...... 15

Life History...... 18

BioiogyandffabitsoftheSpecies...... 23

Spring Emergence of Adults...... 23 Sex Ratio of the Spring Generation...... 24 Emergence ofthe Second Generation...... 30

Third Generation Emergence...... 33

Mating...... 34 FeedingffabitaofAdults...... 35 Le ngth ofLife ofAduits...... 35 T line of Adult Aotivity...... 36

Ov iposition. . . 0 . , ...... 37

Habitat of the Adults ...... 37 FlightHabitaoftheAdu]ts...... ,. 38 ObservationaontheEggStage...... 38 ObseryatjonsontheLarvae,,,...... ,..,...... ,,.., 39 Ha. bitat of the Larvae...... 39

Ov arwintering of Larvae...... s ...... 43 Location of Larvae in Tunnels...... 43 ObservationaonthePupalStage...... 44

mf estation Studies ...... o . s , ...... 44 Peak of the Fall Infestation.,,...,..,.....,.. 46 Distribution of the Fall Infestation...1..1.11 46

La boratory Rearing. . . . e ...... 47

L iterature Cited...... s ...... i . s i . s 50

A ppendix...... i . . i . i . . . . i . . . . i i . . . . . i s . . i . i i . i i . . i . i . . i 52 LIST OF PLATES

Plate Page

1. Larval injury to roots of fennel, uninjured on right, injured on left...... , 7

2. L)amagod carrot showing larval tunne]s,...... ,...., 10

3. Fig. A. Egg of Psila rosae, greatly enlarged Fig. B. Mouthparts of larva, lateral view Fig. C. Dentioles on abdomen of larva, 150X...... 13

4 Larvae of?. roeae.....,.....,...... 14

5 Pupae of?. rosae...... 16

6 Adults of!. roae...... ,....,...,,...,...... ,...... 17

7. Probable seasonal occurrence of P. roeae...... ,...... 20

8. Emergence of first generation adults in the inseotary. Plotted at three day intervals as averages...... 25

9. Emergence of first generation males and females in the insectary. Plotted at three day intervals

as averages...... 27

10. Emergence of first generation adults from traps. Plotted at three day intervals as averages...... 28

li. First generation male and female emergence from traps. Plotted at three day intervals as averages..... 29

12. Emergence of second generation adults in the

in sectary...... s . s . . . s . s . s . . . . 32

13. Map of the Lake Labish Experimental Plots...... 45 LIST OF TABLES

Table Page

1. Lev-ele of Injury Caused by Psila roaae During the Fall and Winter of 1950-51...... ,... 23

2. Emergence of the Carrot Rust Fly in the Surner, 1950... 31

3. Emergence of the Carrot Rust Fly in the Fall, 1950..... 33

4. Duration of Life of Male and Female Carrot Ruit , S pring, 1950...... 36

5. Length of Carrot Rust Fly Larvae During the Winter of

I950-51 ...... 42

6. Depth of Carrot Rust Fly Pupae in Soil, April, 1950.... 44

7. Distribution of an Infestation of the Carrot Rust Fly.. 47

8. Spring Emergence of Adults in Insectary.....,...... 52

9. Spring Emergence of Adults from Traps...... 54 BIOLOGY AND HABITS OF THE CARROT RUST I p ILA ROSAE (FAB.), IN OREGON (DIPTERA: PSILIDAB)

INTRODUCTION

Paila rosas (Fab.), the carrot rust fly, has been a diffi..

cult to control because information was lacking on seasonal history and habits. The writer undertook this investigation in

the hope that a study of this pest under Oregon conditions would

yield information of value f r the control standpoint and

broaden our knowledge of its biology.

ECONOMIC IMPORTANCE. The carrot rust fly is the niost

serious pest of in Oregon. Certain areas in the state

have actually ceased growing the crop commercially because of this

insect. It is not necessary that the entire planting be infested

to result in a failure, Depending upon demand, a low percentage

infestation may cause carrots being grown for canning to be re-

jected. If they are being grown for the fresh market, an infesta-

tion of twenty-five percent may make it impractical for the grower

to separate clean fron wormy carrots.

On occasion, may be damaged to such an extent that

the entire crop goes imharvested.

Insofar as is known, in the state of Oregon, there has

never been a crop failure caused by this peat. In some

regions of the United States, however, great importance is attached to the effect of P. rosae upon this crop; consequently it is a potential threat to the celery growing regions of Jregon.

HISTORY AND DISTRIBUTION. The species was first described by Fabricius (6, p.356) in 1794. The habitat was given as "Kiliae floribus," or Bessarabia, which now belongs to the U.S.S.R., but was at one time a part of Rumania.

The insect received little attention until around 1840, when Curtis (5, p.404-407), in England, in his "Farm ," gave an account of the injury, described the various stages, and suggested control measures.

P. rosae is a recorded pest in Russia, Germany, Austria,

Switzerland, Sweden, France, The British Isles, Canada, United

States, and recently, New Zealand. It has not been reported from

Asia, Africa, South America, or Australia. According to Vihitcomb

(19, p.3), it has never been reported south of parallel forty in

North America.

The carrot rust fly was undoubtedly imported into North

America. There is no record of its presence prior to 1885, at which time Dr. James Fletcher (8, p.15) reared specimens from

carrots he had purchased in an Ottawa market; shortly thereafter, much damage was reported around ììlontreal, Quebec, and Ottawa.

The species vaa first recorded in the United States in

1893. Since its discovery, there has been a general spread to the west and south0 The following paragraphs discuss briefly the occurrence and history of P. rosas in the various states reporting its presence.

Maine was the first state in this country to report the species. The insect is recorded in Vermont and New Hampshire only as museum specimens. Rhode Island and Connecticut have reported dsuage on occasion, but never as severe as neighboring Massachu

setta. Whitcosib (19e p.5) states that after it was reported in

Massachusetts in 1913, each succeeding year found it more preva- lent, and during the late twenties, injury was so general and serious that it was difficult to purchase locally grown carrots free from attack.

Injury has been reported only at intervals in New Jersey, while in New York, Glasgow and Gaines (9, p.412) in 1929, re- ported that the species wa considered a limiting factor in the production of carrots in certain areas. Latest records indicate that the fly is still a problem.

No serious losses were noted in Pennsylvania until 1927.

Infestations in certain areas of this state are the most southerly recorded in North America. After being discovered in 1930 in

Ohio, the species became increasingly important. Publications dealing with the carrot rust fly have emanated from Illinois from time to time, and in Michigan, it did not appear in damaging pro- portions until 1929. 4

No infestations have been reported from the Plain azul Rocky

Mountain regions, however, Melander (13, p.95) states that imiseurn

specimens exist in Colorado.

In the Northwest, Idaho haa the species represented by a museum specimen. Dr. A. L. Melander collected specimens in

Washington in 1908. However, it was not reported as injurious until 1929. Since that timo, Its destructiveness has increased

nearly every year. In 1936, it was found near the Columbia River,

and most carrots in the Puget Sound region were said to be in-

feated. It is interesting to note that only fifteen years after

the first report in the United States, the fly had spread across

the continent to Washington.

Cole and Lovett (4, p.322), in 1921, noted that P. rosas

occurred in Oregon and reported that it was occasionally of

economic importance. Carrot growers along the northwest coast

of Oregon report that they have had to contend with the problem

as long as they can remember. The carrot rust fly was evidently

sporadic in ita outbreaks until 1941-42, at which time it was

causing damage sufficient to result in the initiation of a re-

search project by the Oregon State Experiment Station. The most

severe infestations were centered in the region of Astoria and

the truck garden areas near Portland. By 1943 and 1944, it had becOEne established near Woodburn and two years later, in the Lake Labiah region near Salem. Later a severe infestation was re- ported near Jefferson where over fifty acres of parsnips and

carrots were so damaged that harvesting was considered impractical.

That the insect is still spreading in Oregon is evidenced by the report of an infestation for the first time in Eugene in

1949-50. This infestation was found in a varietal planting of

carrots adjacent to e cannery. Infested carrots had been brought to the packing plant, and flies escaping from the cull pile in- fested the field carrots.

From time to time infestations are reported in the Cor- valus area. Dr. H. A, Soullen and Mr. R. W. Every, both of

this station, report that their home plantings of carrots have

been damaged by this insect at intervals. In March, 1951, a

light infestation was noted at the Entomology Experimental Farm.

Infestations reported thus far in Oregon have been in

Multnomah, Washington, Tillamook, Clatsop, Hood River, Clackamas,

Benton, Marion, Lincoln, Linn, and Lane counties.

HOST PLANTS. In addition to carrots, parsnips, celery, and

, infestations have been reported by Ythitcomb (19,p.6)

on dill, caraway, coriander, fennel, and celeriac. All are members of the botanical family Umbelliferee.

Pettit (17, p.8) of Michigan stated that the species

attacked wild carrot, while Vhitcomb (19, p.6) was unable to find it in that plant in Massachusetts. The author has examined over

100 wild carrots in Oregon, during all seasons of the year, and has found no trace of injury. Chittenden (3, p.29) quotes from a

Scandinavian SOUrCe that the species was taken from turnip and rape. Baker et al. (2, p.123) observed oviposition near the base of potatoes and Atriplex species.

Petherbridge et al. (15, p.381) in England found adult flies in a cage placed over poison hemlock, maculatum.

This plant occurs quite commonly along ditch banks and roadways in Oregon, and an examination of the roots by the author gave in- dication of carrot rust fly injury, but no larvae or pupae were found. The roots of cow , lieracleum lanatum, have been exRmlrIed and show injury very sinilar to that found on carrots.

The only known wild host of the carrot rust fly in Oregon is fannel, Foeniculuin vulgare. Injury to this plant is oharac- terized by the absence of lateral rootlets, a dark-brown tap root, and larval tunnels extending a short distance into the main root. As shown in Plate 1, the surface of the root appears

"chewed," 'with the epidermis and fleshy layers of tissue missing in many areas. That this plant may serve as an important source of carrot rust fly infestation is evidenced by the fact that five puparia were found around the roots of a single fennel plant.

A large field of dill within a few hundred yarda of an infested carrot field was examined but no injury was found on P1te 1. Larval injury to roots of fennel, uninjured on right, injured ori left. this recorded host plant.

Thua, while P rosae has been reported from turnips and

rape, and as ovipositing near potatos and Atriplex 5Decies, it apparently prefers members of the botanical family Urnbelliferae.

Previous to finding the species infesting fennel, the absence of attacks on wild Umbelliferae was believed due to host preference

on the part of the species. however, injured fennel plants were present as weeds in a field of infested carrots, so fennel was probably as attractive a host as the carrots.

NATURE OF INJURY

Only the larval stage of the carrot rust fly is injurious.

This stage inflicts its greatest damage on the roots of carrots, parsnips, and celery. Damage to carrots and parsnips is con- fined to tunneling in the main root, whereas, in celery the principal injury is to the crown.

Injury to very young carrots causes dwarfing and even death. Mature carrots show no evidence of injury unless the tap root is examined. A carrot field may be infested for some time before injury is noticed because the larvae are probably feeding on the lateral rootlets. This point has not been cipletely es- tablished, but all available evidence indicates that they do feed on the small fibrous roots, or the small growing tip, prior to in- testing the tap root. Carrots may, therefore, be examined from time to timo and injury go unnoticed.

Early damage to the main root may be characterized by some- what superficial tunneling of the epidermis. Eventually, the larvae burrow into the flesh. (Plate 2). This later injury is

characterized by small, tortuous tunnels of different lengths, varying in width from a fraction of a millimeter up to a full millimeter. In sorne cases, the tunnels nty extend through the carrot and out the other side, ranifying the entire root, with no one region being favored over another. Inside, asea of rust-colored, larval excrement may be found, hence the naine, carrot rust fly.

Whitonb (19, p.7) states that the foliage of infested plants often has a red or yellow color. Color of foliage may not be an index of damage, as the writer and others at this station have observed healthy carrots with reddish or yellow leaves, while others with lush, green foliage were heavily infested.

During the sxurter of 1950, in the Lake Labish region, damage to celery was observed as extensive tunneling about the crown. Lateral roots presented a "chewed" appearance and were reduced in number in soie cases. Peculiar blister-like pustules were also noted on the inside of the stalks. Beneath the pustules were small, straight tunnels in. which no larvae were found. lo

Plate 2. n

Vhitcomb (19, p.6) reports that coriander, caraway, fexmel, and dill are lightly attacked. The characteriatic damage je a alight chewing on the roots and crown.

STNONYIY AND DESCRIPTION OF THE SPECIES

Fabricius (6, p.356) described the carrot rust fly origin- ally under the name, kueca rosae, in 1794. In 1805, Fabricius

(7, p.319) placed the species in the genus Tephritia. Meigen

(12, p.358) erected the genus Peila in 1826 and placed it under that nauta. Macquart (ii, p.421) listed the species under the genus Pstlomyia in 1835, and etterstedt (zo, p.2402) in 1847, placed it under Scatophaga. According to authorities on the

Diptera, Psila roeae (Fab.) is the correct scientific nane of this insect.

The original description of P. rosas as given by Fabricius in his "Entoxnologia Systematica" follows:

"Roeae 181. M Antennis setarius aeneo atra capita rufo, pedibus testaceis.

Habitat in £iliae floribus.

Parva. Caput ruíum. Thorax & abdien aeneo atra, iimna- culata. Pedos testacei, alae hyalinas, inmaoulata.0

As translated by the author the description reads:

Antennae with shining black arista; podicel brownish yellow, tipped with red. 12

Habitat in Bessarabia.

Small. Head reddish, thorax and abdomen shining black, smooth. Lega brownish-yellaw, wings olear and smooth0

DESCRIPTION OF THE EGG. The eggs are white, and about four times as long as wide, the length varying from 0.6 to 0.8 muli- meters. The surface is marked longitudinally by ridges and furrows and irregular reticulate sculpturing so that it resnbles a peanut shell. Ashby and Wright (i, p.356) in their studies of the im- mature stages of P. rosae, described the egg as having a micro- pylar cap at one end. This cap is a small circular plug with eight sockets around its periphery. (flate 3, Fig. A.)

DESCRIPTION 0F THE LARVA. The newly hatched larva i. practically colorless, but gradually darkens. As growth con-

tinues, it beoies creamy cthite and when fully grown is a straw yellow. (Plate 4)

There are thirteen body segments in all stages. The head

is sharply pointed and posessea a pair of black, mandibular

soleritea, (Plate 3, Fig. B) During the second and third in-

stars, there are indistinct apiracles on the prothoracic seg- ment. The blunt posterior segment bears the dark-colored caudal

spiracles which increase in size frOEn instar to instar.

Ashby and Wright (1, p.359) report that they have found

denticles on the ventral anterior margins of abdiinal segments

one through seven, and on the anterior border of segments one 13

Fig. A. Egg of P. rosae, greatly enlarged

Fig. B. Mouthparts of larva, lateral view

' I

UUUA I-

JLAA.)

'I

'kL1,0. ..J 1)4 uO0J.

O\.NvUt- O

Fig. C. Denticles on abdomen of larva, 150X

Plate 3 1)4

Plate )4, Larvae of P. rosae. 15 through three. The denticles can be seen when the larvae are immersed In 1(011 for about BiX hours, then stained In haernatoxylin.

The denticles then appear as minute toothed projections when viewed under a compound microscope. (Plate 3. Fig. C)

DESCRIPTION OF THE PUPA. The length varies from 4.5 to 5.5 millimeters. The pupa is bright, aniber brown in color, becoming darker with age. It has an oblique anterior end which, when the adult emerges, acts as a lid, remaining hinged at one edge.

(Plat. s)

DESCRIPTION OF THE ADULT. P. rosac ii small, four to five millimeters long, shining black, with green irridescence. The wings are thin, irridescent, and extend as much as one-half their

length beyond the tip of the abdonen when at rest. The head ii

globoso arid yellowish brown. The eyes are brawn. The front

slopes inward. The basal segment of the antennae is yellowish,

and the terminal one is tipped with black. The arista is

yellowish. The lege are yellow and pubescent, and the tard

are five segmented with two claws. The abdomen is oval in the

male and conical in the female and is coaiposed of six segments.

The female is slightly larger than the male and is equipped with

a contractile ovipositor. (Plate 6) Plate 5. pae of P. roae,

I-a 'I'

L______n' -

q L: w

P1te 6. Adults of P. rosaê. 18

LIFE HISTORY

In Oregon the carrot ruat fly overwintera predOEninantly in the larval stage. Larvae continue to feed upon the carrot roots during the winter and pupate in the winter and early spring.

Adult emergence begins the latter part of April and extends into June. The femaba usually lay their eggs Within two or three inches of the host. The eggs are depoøited under a clod or lump of soil and sometimes on the crown or foliage of the plant. The eggs hatch in five to ten days depending upon temperature. The larvae descend into the soil and begin feeding on the small root- lets extending from the main tap root of the carrot. Approxi- mately thirty days are spent in the larval stage. Ashby and

Wright (1, p.357) report three larval Inatars, which is the usual number for many Diptera. The three instara range in length as follows: first instar 0.6 to 2.0 millImeters, second instar 2.0 to 5.0 millimeters, and the third instar 5.0 to 10.0 millimeters. Evidence that the larvae do not enter the main tap root until the aecond, or even the third instar will be discussed later.

After feeding has ceased, the larvae leave the host and begin preparations for pupation. The prepupal stage laets about five days and pupation is complete in approximately thirty days. 19

During July the adults begin to energe, rate, and lay eggs

for another generation. Larval feeding and pupation again require

about 65 days.

Some of the pupae of the second generation remain in the soil

through the winter and give rise to adults in the spring. From

the remaining pupae, third generation adults begin to emerge during

September and October and lay eggs for the fall brood of lame.

The life cycle of the third generation does not follow the pattern

of the first or second generation. Undoubtedly larval development

is inhibited during the extremes of the winter to such an extent that the larval stage requires a number of months for its com- pletion rather than the normal 30 days. The time required for the third generation to complete its life cycle would necessarily be considerably longer than that for the first two generations.

Plate 7 illustrates the seasonal occurrence of the species.

As to the number of generations per year of the carrot rust fly, some workers report two, but the majority state that there are two and a partial third generations. Hanson and

Webster (lo, p.24) report two complete generations and a partial third in Vashington. Äorr1son (unpublished data) (14) believes there are two complete generations and at least a partial third in Oregon. All available literature, as well as the writer's ob- eervations, indicates that the carrot rust fly completes its life Pupae?

Larvae overnter in Carrots

Eggs?

__Adults? ______Pupae Overwinter

flaxwae

J Eggs j Adilts

Pupae

Larvae

Eggs r J Adults

1 3u1d23 lI May June July Aug. Sept. Oct.. Nov. Dec. Jan. Feb. Mar. Apr.

Plate 7, Probable seasonal occurrence o P. rosae 21 cycle in about 75 days. Since adult emergence is spread over a period of approximately 45 days, eggs laid in April will become mature larvae in May and emerge as adult flies in the early part of July. Thus, there would be sufficient time for the second

generation to complete its life cycle, and a third to begin.

Adults arising from the second generation emerge during the first part of September, mate, and iay eggs for a third generation.

(Plato 7)

The following evidence i8 introduced to substantiate the belief that there are two complete generations and at least a partial third in Oregon.

1. Garrote in the Lake Labish experimental plots were not available as hosts for the spring generation, but were infested by the second generation. The spring generation had completed

its emergence by June 5, 1950, and carrots were not attractive for ovipoeition until about ten days after this date. Samples

of carrots pulled from mid-June through August were found to be free of injuries until late August. Consequently, the resulting

infestation must have been caused by the second generation.

(Plate 7, Life History Graph) This is corroborated by the fact that eggs were not found until late July, which would be the time

of emergence of the second generation of flies. Rust fly maggots were found in August and puparie. in September. Therefore, adults 22 which emerged from the pupae of this suxmer infestation during Sep-

tember and October produced the winter or third generation in-

f estati on

2. Fifty pupae of the carrot rust fly were collected in

Septonber and October of 1960, and 15 flies ierged, but no eggs

were obtained. 1orrison (unpublished data) (14) reported that

during September and October, 1944, at Woodburzi, Oregon, under

natural conditions, sixty percent of the eocond generation pupae

collected emerged as adults. Petherbridge et a].. (is, p.387),

in England, report that adu1t hae been taken by sweeping as

late as November 11, and that eggs were laid by the fenmies.

3. Samples of carrots were collected at approximate

weekly intervals from the Lake Labish experimental plots during

the fall and winter of 1950-51. The data in Table i show that

the percentage of injured carrots increased as the season pro-

gressed, reached a peak and leveled off in December. Because of

this increase, there must have been an emergence of adults which

probably represented the third generation. 23

TABLE i

Levels of Injury Cau8ed by Pella rosae During the Fall and Winter of 1950-51

Number Number of of Carrots Tota]. Percent Date Carrots Injured Injuries Injured Aug.-Nov., 1950 100 0 0 0.0 Nov. 5, 1950 66 4 6.1 Nov. lO 58 6 6 10.3 No,. 18 50 6 6 12.0 Nov. 25 50 8 8 16.0 Dec. 2 50 10 10 20.0 Dec. 9 50 16 22 32.0 Dec. 22 50 32 51 64.0 Jan. 13, 1951 50 32 68 64.0 Jan. 26 50 20 34 40.0 Mar. 1 105 65 131 61.9

BI0LO(T AND HABITS 0F THE SPECIES

The following pages deal with observations carried out in the insectary at the itomo1ogy Experimental Farm and the Lake

Labish experimental plots, plus limited observations made on the farm of Mr. Louie Garre, near Greahaxn, Oregon.

SFING EMERGENCE OF ADULTS. A total of 264 pupae were collected at the Lake Labish experimental plots in the spring of

1950. These were sifted and floated fran the soil, placed in

Petri dishes, covered with moist soil, and confined in a cage constructed froen a five gallon oil can with a screw-top 'vial inserted in the lid to collect the emerging flies. However, the 24 adulta were rarely found in the vial. In order to collect fliea from the chamber, the lid had to be removed. A few escaped but were readily recovered with an aspirator.

The humidity inside the emergence chamber was known to be high because of condensation on the inside walls. Temperatures in-.

side the chamber were cool when compared with outside. t)n one occasion, the air of the insactary was seven degrees warmer than the cage.

The first flies began to emerge from the chamber April 20, and continued until July 5. From the 264 pupae collected, 199 flies, or 15.4 percent, emerged. Plate 8 shows the emergence graphically. Data on this graph are plotted as averages for three

day intervals. Where only one fly emerged in three days, it was not plotted. For the day to day emergence, the reader is referred to the appendix.

sx RATIO OF THE SPRING GENERATION. Emerging flies were

collected each day, anesthetized with ether, then examined with a hand lens to determine the sex. The criterion used for differentia- tion of the sexes was the bluntness of the end of the abdomen. As mentioned previously, the female's abdomen tapers to a point at the end. Exposure to the ether vapors for a minute or so usually

rendered adults unconscious. 0n a few occasions an individual

failed to recover. 1H

12 t', a,

-.4

ç-.' o

a) -o Ef z

I I I I I I I

1 214 27 30 6 Q 12 1 iR 21 April May Da t e

Plate 8. Emergence of first goreratlon a1ults in the insectary. Plotted at three day intervals as averages. 26

Of the 199 flies that emerged from the chamber 115, or

57.8 percent, were females and 84, or 42.2 percent, were niales.

During the first few days of emergence, male flies outnumbered

females considerably. For the day to day nergence of male and female flies during the spring of 1950, see the appendix. Plate 9

shows male and female emergence plotted at three day intervals as averages.

Further data on the spring emergence were gathered rrom

traps covering soil from the Lake Labish experimental plots.

The soil and traps were placed outside on the Entomology Experi- mental Farm. Temperatures inside these traps were considerably higher than those in the insectary.

Flies began to emerge from this soil April 26 and con- tinued until June 4. A total of 143 flies emerged; 54.5 percent were females and 45.5 percent were males. Plates 10 and 11 por- tray this emergence graphically. The complete data for this group

of flies 18 appended. The peak of emergence was reached simul- taneously with that in the in.00tary, and the sex ratio was nearly the sane.

Thus, of the 342 flies from the traps and the emergence chamber, the peak of emergence was reached May 9, when 57.3 per- cent of the total had emerged. Females represented 66.4 percent and males, 43.6 percent of the total. These figures agree quite Fern1 emerence Loth sexes

.!ie eer-ence

7

r-I

O)1 iL.

3

i

I '..-1 I l'i i i i I I i i I i N- 2L 21 27 30 3 ó 9 1, 1 I 7 30 2 L Aprii 1.iay June Date

Plate 9. Emergence of first generation males and females in the insectary. Plotted at three day intervals as averages. i

a

r.

3

Aprii Jurie

J) a t o

Plate 10. Emergence of first generation adults from traps. Plotted at three day intervals as averages. Female emerence Both sexes - ---Iale emerence

a)

ç-4 o

-

2

30 3 9 12 1 13 21 2! 27 30 2 Arri1 May June Da t e

Plate 11. First generation male and female emergence from traps. Plotted at three day intervals as averages. 30 closely with those of thitcomb (19, p.14) who reported that of 259 flies, 57.5 percent were females and 42.5 percent were males.

E1ERGENCE OF E SECOND GENERATION. Since carrots were planted too late at the Labish experimental plots to be infested by the spring generation, information had to be derived from other sources. A vegetable grower in the Gresham, Oregon, region re- ported an infestation of the carrot rust fly in July. Thu area

'was visited July 18, and 66 pupae were sifted from the soil. The infestation was rather light, this being the reason for the rela- tively few collected. Pupation was apparently complete by this time as over fifty injured carrots were examined and only one maggot was found.

Adult emergence from these pupae began July 22 and ended

August 4, lasting only fourteen days. A total of forty one, or 73.2 percent, emerged. The peak of emergence was reached

July 28. The sex ratio of the summer generation of flies very nearly approached that of the spring generation. Table 2 gives the emergence of this generation. 31

TABLE 2

Emergence of the Carrot Rust Fly in the Summer, 1950

Date Females Males Total July22 1 2 3 24 1 2 3 25 1 1 2 26 3 1 4 27 3 2 5 28 5 3 8 29 2 2 4 31 2 2 4 Aug. 1 2 1 3 2 2 0 2 3 0 0 0 4 1 2 3

Total 23 18 41 Percent 56.1 43.9 73.2

Male emergence did not preoede female emergence to any great

degree, in fact the peak of male emergence ooinoided with that of the females. Plate 12 shows the pattern of emergence for the

summer generation.

These data may not be representative of the true second generation emergence, as adult emergence undoubtedly requires more than fourteen days for completion. Emergence probably began some tinte prior to July 22. Carrots which were examined in the

Grosham region showed injury to the main tap root, but in only one instance was a larva found in the more than fifty injured carrots exemined. Also, a number of empty pupal cases were sifted 7

Q) -I r-4 O

ç-1 o r; aQ)

i

22 23 2L. 25 2u 27 2 29 30 31 1 2 3 July Auut Da t e

Plate 12. Emergence of Second Generation Adults in the Insectary. 33 from the soil. It follows, then, that most of the larvae had pu- pated by July 22. For these reasons, it is considered probable that second generation adult emergence began in early July and con- tinued into August.

THIRD GENERATION EJERGENCE. Fifty pupae from the second generation were collected at the Lake Labish experimental plots on

September 23, 1950. Of these, fifteen adult. emerged, beginning

September 24, and ending October 4. Table 3 gives the dates of emergence.

TABLE 3

Emergence of the Carrot Rust Fly in the Fall, 1950

Number Date Emerged Fele Mal.. September 24 2 1 1 25 1 1 0 26 1 1 0 27 1 0 1 28 4 3 1 29 3 2 1 30 1 1 0 October 1 1 o i 2 0 0 0 3 0 0 0 4 1 0 1

Total 15 9 6 Percent 30 60 40 As the flies emerged they were placed in an outdoor cage con- taining potted carrots. Since the rains began very early in the fall of 1950 and temperatures were rather low, it ii probable that mating did not occur, as no eggs were obtained.

MATING. °n April 25, and 27, 1950, males and females were placed on potted carrots and covered with a lamp chimney. On

April 29, the day mating was first noted, the maximum temperature was 66°F., the highest since the day the flies under observation had emerged. Other observations were subsequently made, and the maximum temperature in each case was 600F. or above.

On every occasion that mating was observed both sexes were suspended upside down from the gauss covering the lamp chimney.

The male covered the female's body with his own and the tips of their abdonene were fused. During copulation, the male was quite still except for slight abdominal movements, The female on the other hand, continually rubbed her front legs together. The wings of the female were held at an angle fr the body, while the male kept his wings in the normal position, that is, folded flat, back along the dorsum of the abdomen. On one occasion the writer observed the beginning of copulation. The female, rest-

Ing on the side of the lamp chimney, was approached by the male from the rear, She offered no resistance and, after union of the genital organs had taken place, she moved to the gauze which covered the lamp chimney, carrying the male on her back. In this 36 particular case, mating went on uninterruptedly for thirty-eight minutes. At this time the lamp chimney as jarred and copulation ceased.

t&ting has only been observed in the insectary. It is not known where mating occurs in the field.

FEEDING HABITS ÛF ADULTS. Adults confined in lamp chimneys were seen to forage about, pressing their mouthparts to the carrot foliage, probably feeding on whatever organic matter was present.

Glass slides covered with dilute honey were placed inside the chimneys. The flies appeared to be greatly attracted to the honey as they fed readily.

LENGTH OF LIFE OF ADULTS. Their sex having first been determined, twelve pairs of fijes which emerged during May, 1950, were placed in lamp chimneys covering potted carrots.

The average length of life for the males was 5.8 days and for the females, 6.6 days. The length of life for each fly is shown in Table 4.

The average length of life for males and females conbined was 6.2 days, whereas, V'hitcnb (19, p.14) reported that in

Massachusetts, under insectary conditions flies lived 4.3 days. 36

TABLE 4

Duration of Life of iàle and Female Carrot Rust Flies, Spring 1950

Length of Life Fly Number Female Male 1 4 3 2 2 6 3 7 1 4 11 9 5 14 5 6 6 8 7 7 11 8 3 10 9 11 3 10 2 2 11 5 6 12 7 5

Total 79 69 Average 6.6 days 5.8 days

TIME OF ADULT ACTIVITY. The carrot rust fly is active about

its host at the close of the day, and less noticeably during the

warmer, brighter hours. This writer, in the company of Dr. D. C.

Mote arid Mr. H. E. Morrison, both of the Oregon State Experiment

Station, observed on August 10, 1950, that adult activity became

most noticeable about six or seven in the evening, Pacific Day..

light Savings Time. Adults were so numerous at one time that it was possible to observe them alighting on the carrots. Flies were

active until sundown and may have remained in the field even later,

but it was impossible to see them. 37 Carrots have been swept from 5:30 a.m. uzrtll 11:00 at the Jke Labish region, but no adults were captured. Petherbridgo and Wright (16, p.355) in England, reported a few flies In carrot fields from 3:30 a.m. to 10:00 a.ra.

OVIPOSITION. Adult females were observed ovipositing in carrot fieldø on three separate occasions. The pattern was the same in all cases. Oviposition occurred during the late afternoon, about 7:00 or 8:00 p.m. A fenale would alight on the foliage or the ground near a carrot. After a few minutes spent foraging about, she would select a spot for her eggs, turn around and work the end of her abdomen under a small clod of earth. Thirty to forty seconds later, she would withdraw her abdomen and crawl or fly away. On most occasione female flies simply crawled or flew a few thche away and oviposited again. One female was seen to lay eggs in three places within an area of approximately one square foot.

IIkBITkT OF THE ADULTS. The absence of flies from carrot fields during the day led various workers to attempt to find their location. Baker et al. (2), Petherbridge and Wright (16), and

Watkins and Miner (18) all reported that the flies frequent the hedges and vegetation surrounding carrot fields until late after- noon at which tine they begin moving into the fields for cvi- position.

In the early afternoon, the writer, in the company of interested persons, observed carrot rust flies on the underside of corn leaves. The corri plante wore iT'imediately adjacent to a carrot field. Flies have also been swept from trees and shrubs bordering carrot fields in the morning and afternoon. Various workers have reported that the heaviest infestation in a plot is in the position nearest hedges and shrubs. Data on the fall infestation in Oregon show this to be true. The distribu-. tion of an infestation is discussed in irtore detail under population studies.

FLIGHT HABITS OF T1E ADULTS. Ag adults approach a carrot field fron the direction of th setting sun, they are quite low to the ground, many not more than a foot or so above lt. Aft.y alighting in the field, most of th crawl about on the soil or make short flights very close to the ground. For this reason, it is difficult to pick them up in a sweeping net. Their flight le rapid and they chango direction readily. They do not appear to be easily frightened when aproaohed, as adult flies have been captured in the field with an aspirator.

OBSERVATIONS ON THE EGG STAGE. The eggs are laid very near the host, usually Within one Inch or less, and occasionally are found on the foliage and the crown. The female does not deposit all her eggs in one location but skips around, laying three or four et each oviposition. As many as seven eggs have been found under a clod of soil after a female was seen to oviposit there. 39

Dissection of fexnales has revealed that eighteen to twenty eggs are usually found inside the body. A single female laid twelve eggs in the insootary and one was seen to lay eleven in the field.

Whitonb (19, p.15), in Massachusetts, reports that eggs hatch in 6.17 to 9.7 days under insectary conditions.

Eggs laid in May, 1950, were checked daily to ascertain the incubation period under natural temperature conditions. Some of the eggs under observation hatched in 5 days, while others re- quired up to 9 days.

OBSERVATIONS ON THE LARVAE. The discussion to follow con- cerne observations made during the summer and winter of 1950-51.

Habitat of the Larvae. Based on the author's observations, there are indications that rust fly larvae feed on the fibroua roots and growing tip of carrots until the late second or third instar, at which time they enter the main root and cause their typical damage.

In other areas, workers on the biology of this insect re- port that upon hatching, the larvae enter the main root of carrots almost immediately.

The writer expected to find injured carrots harboring young larvae soon after hatching. When neither damage nor larvae were found, the ob8ervations were misconstrued to denote the absence of an infestation. Later in the season large numbers of injured carrots containing third instar larvae wore found.

The f allowing evidence suggests that the larvae of this in- sect do not enter the main root of carrots until the late second or early third instar. In some cases they may not enter at all.

In nay, adults wore introduced into cages covering carrots growing in twelve number ten cans. Two weeks after eggs were ob-. served on the soil, carrots were removed frau one of the cans and examined for injury. None could be found. A few days later those in seven cans were examined and no injuries could be found. Thus, approximately three weeks after oviposition, none of the carrots were damaged. Four of the cans were set aside until sometne in July, at which time their contents were examined and nearly every plant in two of the cans was injured. The soil in the cans was sifted and nine pupae were obtained. Consequently, injury to the main tap root of the carrots did not take place until about three weeks after oviposition, and probably later.

During the early part of August, an examination of the tap root of carrots at the Lake Labish experimental plots revealed no injuries other than enall, clean tunnels which extended inward a very short distance. These tunnels were examined under a micro- scope and no larvae or their typical rust-colored excrement were found. For a while, the author had about reached the conclusion that there was no infestation in the region. Eggs had been laid, they had hatched, and yet two weeks later no larvae could be found, 41

nor could any definite injurer attributable to the carrot rust fly

be found. But in late August, larvae which were in the third instar

wre found, and around the first of September, pupae were collected.

This, then, would seem to indicate that actual infestation and in-

jury to carrots did not occur until the insect reached a stage of

development more advanced than the first or second instar.

The significance of the absence of larvae and injured carrots

until two or three weeks after eggs had hatched was not olear until

November 6, 1950, when carrots which had been exposed to the fall

generation were examined. At this time a few were seen to have

typical rust fly injuries, and larvae were also found. Thus, the

pattern was the same; injury frOEn the fall generation was not

found until a month or more after adult emergence began. It was

at this point that the possibility became apparent that larvae

exist in the soil for a considerable period before tunneling into

the carrot.

Thereupon it 'was decided to make trips at approximate week-

'y intervals to the Lake Labish region. Carrots were to be selected randomly in an attempt to see if the infestation increased as time passed and if the larvae present in carrots varied in develop- mental levels. Table 5 shows that only larvae of the third in- star were found in carrots during November, December and January of the past winter, and the data in Table 1 demonstrate that as the winter progressed, injury increased. These data taken 42 together are believed to indicate that larvae do not cause actual damage to the edible portion of carrots until after the second molt.

TABLE 5

Length of Carrot Ruat Fly Larvae During the Muter of 1950-51

Length in Millimeters Nov. Dec. Jan. 6.3 15.3 8.7 6.1 6.2 8.4 6.1 6.2 7.2 6.3 7.7 7.9 6.7 7.0 7.7 6.9 7.0 7.7 7.7 7.4 6.7 7.4 8.0 7.0 7.6 8.5 8.1 6.7 6.9 6.9 9.3 7.4 7.9 8.0 8.0 7.4 7.9 7.0 7.0 7.6 7.9

Average 6.9 7.4 7.6

This writer has observed fennel plants itose main injury was surface feeding on the tap root and the loss of the lateral

roots. Similar synptaus were found on poison hemlock and cow 43 parsnip, though it i not known if the carrot rust fly caused them.

Vthitcib (19, p.6) reports that damage to coriander, caraway, fennel, dill, and celery is evidenced by a chewing on the surface of the roots and crown.

A logical assumption is that if larvae do not tunnel into the roots of all their hosts, they might not at all times bore into the main tap root of carrots. The tap root of carrots is larger and more succulent than that of the other hosts, but if the carrot is in a vigorous growing condition, with numerous lateral roots, the larvae might not enter the edible portion until the supply of lateral rootlets had been reduced, or perhaps they would not enter at all.

Over'wintering of Larvae. In Oregon, the carrot rust fly overwinters in the larval as well as the pupal stage. During the winter of 1950-51, even as late as arch, the author removed larvae from infested carrots and sifted them from the soil.

Location of Larvae in Tunnel.. Infested carrots were in- variably dissected to ascertain the presence or absence of larvae.

In the course of the dissections, considerable care had to be given to initial cutting es the larvae were usually near the sur- face, and only rarely found deep inside. When infested oarrats are removed from the soil, many of the larvae are seen with varying portions of the abdomen protruding from the tunnels. 44

OBSERVATIÛNS O ThE PUPAL STAGE. Pupae of the carrot rust fly are usually found in close proximity to their host, in moat

cases within an inch or two. L) occasion, they may be found appressed to the root. )f 31 pupae recovered on one occasion,

81 percent were in the upper six inches of soil. Table G gives

the distribution of pupae recovered during the spring of 1950.

Five pupae were found adjacent to the roots of a fennel

plant. This sas the greatest number noted around a single host.

TABLE 8

Depth of Carrot Rust Fly Pupae in Soil April, 1950

Number of Pupae Found at Various Levels Sample Number 0-3 inches 3-6 inches 6-? inches

1 2 3 2 2 3 6 2 3 0 1 1 4 3 7 1

Total 8 17 6 Percent of Total 26 55 19

No data were taken on the number of pupae per infested

carrot, since the planta grow so close together.

INFESTATION STUDIES. The discussion to follow concerns the winter infestation in the Lake Labish region. The plots used for

this study were untreated areas in a replicated soil insecticide

experiment. Plate 13 showa the location of the plata and the Nu N T

C OR Pl Cntnoi s RIANS Cutiv

- 2- z Z lREflTIt) 2 IuInitI) Tui lUID z Ciitu Soit 5oii Sou (:nRRors CnRROTS o X e

- - -

tIflNDRRflltS

R O fi D

01 Plate 13. Map of the Lake Labish Experimental Plots. 46 surrounding vegetation.

Peak of the Fall Infestation. Random samples of carrots were taken at approximate weekly intervals from check plot nunber three, during the fall and winter of 1950-51. An examination of these carrots showed that as the season progressed, the infestation be- came heavier. As shown in Table 1, the peak of the infestation was reached in December. It is presumed that the number of injured carrots leveled off after this time. No further data were ob.. tamed after 11arch 1, 1951.

Distribution of the Fall Infestation. Carrot growers in

Oregon report that injury is greatest around the edges of a carrot field and in the part adjacent to hedges and wooded areas. In order to verify these reports, the following study was made. Data were obtained during the first part of .4arch 1951. Random samples of carrots were taken from untreated plot number one, with di- mansions of 16 by 200 feet. The plot was divided into quarters,

It was planned to examine twenty-five samples of five carrots each from every quarter, but in a few cases carrots were unobtainable in the spot selected for sampling.

Au examination of Plate 13 shows that this plot was bordered on the south by a fill bank covered with weeds, shrubs arid brambles.

As ahawn in Table 7 injury was greatest in the part of the field adjacent to shrubs arid hedges. If dispersal were governed by the 47 wind or by the attractiveness of the host, one would expect a

relatively even infestation throughout this plot. These data seem to indicate that the dispersal of the carrot rust fly i not general but is influenced by distance and that when the females fly to the carrot fields in the evening, they make relatively short trip e.

TABLE 7

Distribution of an Infestation of the Carrot Rust Fly

Location Number of Number Injuries of Carrots Number Percent of per Sample Examined Injured Injured Injuries Carrot

Plot #1 North 125 36 28.8 45 0.4 Second 125 35 28.0 49 0.4 Third 115 44 38.3 66 0.6 South * 115 62 53.9 118 1.0

lABORATORY REARING

All attempts at rearing the carrot rust fly ended in failure. It is believed, however, that techniques can be developed which would make the project successful.

Large numbers of male and female flies were obtained in the spring of 1950, during studies on emergence. These flies were placed in lamp chimneys and in small cages covered with plastic screen. Each lamp chimney enclosed a small carrot gr-ing in a 48 test tube of soil. Adult flies mated inside the chimneys and laid eggs; however, it was so difficult to keep the carrots supplied with water that the constant wetting and drying of the eggs re- sulted in no hatching, or else the larvae failed to develop on the poorly growing carrots. Adults were also placed in cages covering seedling carrots growing in number ten cans. Oviposition occurred, and some of the eggs hatched, but again, the soil had a tendency to dry out and the carrots showed poor growth. There was no evi- dence of larval injury.

Flies were also placed in two 4 by 4 foot cages covered with 28 by 28 plastic insect screen. It was found previously that screen 16 by 16 would not confine the adults. These cages were placed outside and covered twelve number ten cans growing seedling carrots. Flies were introduced into these cages from timo to time during the month of May.

About two weeks after eggs were noted, soue of the carrots were examined for rust fly injury; since none was found, it was concluded that there was no infestation. The remaining carrots were later found to be infested. A few pupae were recovered, but no adults emerged.

Attempts were made to rear larvae frasi eggs, but these failed. Eggs were collected in the field and laboratory in 1950.

They were placed on slices of carrots and on damp blotting paper inside Lutz plaster of Paris rearing cages. The eggs kept on 49 blotting paper were ruined by molds and those placed on carrot slices failed to hatch.

Additional eggs were collected August 10, 1950. Of 47 eggs collected, only twelve were unhatched. These were placed on soil inside Lutz plaster of Paris cages and still no hatching occurred.

It is probable that the twelve eggs were riot vi1e.

Twenty five second generation pupae were collected in

October, 1950. Under rot temperature conditions, twenty-three adults emerged over a period of four weeks, but on no occasion were a male and female available for mating. Hence, the author was unable to induce an infestation under laboratory conditions. LITERATURE CITED

1. Ashby, D. G. and D. W. Wright. The immature ßtagee of the . Transactions of the royal entiological .ociety of London, 97(14)s355-379. 1946.

2. Baker, F. T., et al. Observations on the biology of the carrot fly (Psila rosae Fab.): Assembling and oviposition. Annals of applied biolor 29 115-125. 1942.

3. Chittenden, F. if. The carrot rust fly. United States depart- ment of agriculture bulletin number 35 n.s.a 26-32. 1902.

4. Cole, F. R. and A. L. Lovett. An annotated list of the Diptera (flies) of Oregon. California academy of science 11(15):].97-344. 1921.

5. Curtis, Johu. Farm Insects. London, Blackie and Sons, 1840. 528p.

6. Fabrioiue, Johann C. Entoinologia Systexnatica. Hafuiae, Proft, Vol. 4, 1794. 472 p.

7. Fabricius, Johann C. Systexna Antliatorum. Brunevigac, Reichard, 1805. 372p.

8. Fletcher, James. Carrot fly (Psila rosao Fab.). Canada department of agriculture entaology report 1885. p.15.

9. Glasgow, Hugh and J. G. Gaines. The carrot rust fly problem in New York, Journal of economic entomolor 22(2)z412-416. 1929.

10. Hanson, A. J, and R. L, Webster. The carrot rust fly. Bulletin of the Washington agricultural experiment station, ntber 405. 1941. 24p.

11. Macquart, Joan. Histoire Naturelle des insectes Dipteres. Paris, Roret, Vol. 1, 1835. 578p.

12. Meigen, Johann W. Systematische Beschreibung der b&rÑnnten europaisclien zweiflugeligen Insekten. Aachen and Hmm, Vol. 5, 1826. 4OSp.

13. (elander, A. L. Synopsis of the dipterous family Psilidae. Psyche 279l-101. 1920. 51

14. Morrison, H. E. and W. B. Iasmusaen. The carrot rust fly, Pßila rosae (Fabr,). Unpublished biennial report to the Oregon State Experiment Station. 1943-1944. 33p.

15. Petherbridge, F. R., D. W. Wright, and P. G. Davies. Investi- cations on the biology and control of the carrot fly (Psila rosae F.), Annals of applied biology 29:380-392. 1942.

16. Petherbridge, F. R. and D. W. Wright. Further investigations on the biology and control of the carrot fly (Psila rosae F.). Annals of applied biology 30:348-358. 1943.

17. Pettit, R. H. Carrot rust fly found in Michigan. Michigan agricultural experiment station quarterly bulletin 13:119-121. 1931.

18. Watkins, T. C. and F. D. Miner. Flight habita of carrot rust flies suggest possible method of control. Journal of economic entomology 36(4):586-588. 1943.

19. ìhitcomb, W. D. The carrot rust fly. iaasachusette agri- cultural exporiment 3tation bulletin 352. 1938. 36p.

20. Zetterstedt, Johann W. Diptora Bcarìdinaviae deposita et descripta. Lund, Verfasser, Vol. 6, 1847. 41?p. 52

APPENDIX

Table 8

Spring Emergence of Adulta in the Insootary

Number of Number of Date Total Females Malea

April 20 3 1 2 21 5 0 5 22 8 3 5 23 6 1 4 24 0 0 0 25 3 1 2 26 1 0 1 27 4 3 1 28 8 6 2 29 10 5 5 30 5 3 2 May 1 4 1 3 2 3 1 2 3 9 5 4 4 9 5 4 5 5 3 2 6 9 6 3 7 0 0 0 8 9 6 3 9 20 13 7 10 14 5 6 11 11 8 3 12 10 8 2 13 6 6 0 14 - - - 15 10 6 4 16 3 1 2 17 6 3 3 18 0 0 0 19 - - - 20 4 2 2 21 0 0 0 22 - - - 53

't) Number of Number of Date Total Femaba Males

May 23 6 4 2 24 3 2 1 25 0 0 0 26 0 0 0 27 0 0 0 28 - - - 29 4 2 2 30 0 0 0 31 0 0 0 June 1 0 0 0 2 0 0 0 3 0 0 0 4 1 1 0 5 1 1 0 6 0 0 0

Totals 199 115 84

Sex Ratio 57.8% 42.2% 54

Table 9

Spring Emergence of Adults from Traps

Number of Number of Date Total Females Males

April 26 1. 1 0 27 2 2 0 28 4 0 4 29 13 3 10 30 4 2 2 May 1 6 2 4 2 5 1 4 3 11 6 5 4 8 5 3 5 0 0 0 6 4 4 0 7 0 0 0 8 1]. 6 5 9 7 4 3 10 8 6 2 11 0 0 0 12 - - - 13 12 6 6 14 - - - 15 8 5 3 16 3 2 1 17 2 2 0 18 - - - 19 0 0 0 20 2 1 1 21 - - - 22 - - - 23 1]. 8 3 24 3 2 1 25 4 2 2 26 6 4 2 27 0 0 0 28 0 0 0 29 4 1 3 30 3 2 1 31 0 0 0 55

(Con't) Number of Number of Date Total Female e Malee

June 1 0 0 0 2 0 0 0 $ o o o 4 1 1 0 5 0 0 0 6 0 0 0

Totals 143 78 65

Sex Ratio 54.5$ 45.5%