pee,

STATES DI DEPARTMENT OF AGRICULTURE
BULLETIN No. 640

Contribution from the Bureau of Entomology
L. O. HOWARD, Chief

By

- E. A. BACK, Entomologist, and C. E. PEMBERTON, Assistant
- Entomologist, Mediterranean and Other
Fruit Fly Investigations

CONTENTS

Page
Distribution Throughout the World . .

stablishment and Spread in Hawail. .
How the Fruit Fly got into Hawaii. . .
| Losses Incurred Through the Fruit Fly .
What the Mediterranean Fruit Fly is Like

_ Fruits, Nuts, and Vegetables Attacked
Host Fruits of Commercial Value . . .
Artificial Methods of Control not Satis-
factory Under Hawaiian Conditions . 24

2
3
4
5
x
1
5

—_

f Page
The Campaign Against the Fruit Fly in
Hawatilic Talal evel ot stlatse totem a. am
Natural Control of the Fruit Fly... . 37
Quarantine Measures to Prevent Intro-
Guctonm yc ate: 2) a) etic tos) oh) ree
WUMIBEY hah oh & ye? 0 ta osha ene, (0, ee

-

WASHINGTON
GOVERNMENT PRINTING OFFICE
1918

NE OF THE WORST enemies of fruit grown in ©
tropical and semitropical countries is the Medi- _
terranean fruit fly. Constant vigilance is necessary _
to prevent its establishment in North America. Itis —
particularly destructive because it is difficult to con-
trol and attacks many kinds of fruits, nuts, and vege- |
tables. In the Hawaiian Islands, where it has caused _
great damage since 1910, it attacks 72 kinds of fruits.
A partial list of these contains oranges, grapefruit,
lemons, limes, kumquats, tangerines, peaches, apples,
figs, apricots, bananas, mangoes, avocados, sapotas,
loguats, persimmons, guavas, quinces, papayas,
pears, plums, grapes, eggplant, tomatoes, and even
cotton bolls. Most of these are now grown or canbe , |
grown in our Southern States, the Gulf region, and = |
California and the Southwest. 3

The purpose of this bulletin is to give alike to the
citizen of Hawaii, the fruit grower of the United
States mainland, and the traveler information that
will help to convey a clear conception of the difficult
problem that has developed with the introduction of
the Mediterranean fruit fly into the Hawaiian Is-
lands. The pest can be kept out of the rich semi-
tropical fruit-growing sections of the United States
only by the hearty and intelligent cooperation of all. _

Dp. of De
APR 47 1919

a ee

UNITED STATES DEPARTMENT OF AGRICULTURE

; BULLETIN No. 640 ,

N

Contribution from the Bureau of Entomolegy
L. O. HOWARD, Chief

Washington, D.C. Vv April 8, 1918

THE MEDITERRANEAN FRUIT FLY.

CONTENTS.

Page. Page.
Distribution throughout the world............ 2 | Artificial methods of control not satisfactory
Establishment and spread in Hawaii........-.. 3 under Hawaiian conditions...............-- 24
How the fruit fly got into Hawaii........-..., 4 | The campaign against the fruit fly in Hawaii.. 26
Losses incurred through the fruit fly........-.- 5 | Natural control of the fruit fly..............-- 37
What the Mediterranean fruit fly is like....... 7 | Quarentine measures to prevent introduction. 41
Britis nprs and. veretablesattacked=-+.---- +i) | “SUIMIMAry. 22 222 sce ce eae seks soa vec eocce ese 42
Host fruits of commercial value.......2..-..--- 15

HE HORTICULTURAL DEVELOPMENT of the Hawaiian
Islands has been almost stopped since 1910 by the activity of two
fruit-fly pests—the Mediterranean fruit fly’ and the melon fly.??

These two pests are being intercepted continually by quarantine
officials at our ports of entry and they are therefore feared by, and are
of vital interest to, every fruit and vegetable grower in the warmer por-
tions of the Pacific and Gulf coast States. very possible barrier to
the establishment of these pests on the mainland United States is being
erected by the Federal Horticultural Board, working in cooperation
with State officials. Quarantines now regulate the movement of
horticultural products from infested countries; hence the greatest
danger to California, Florida, and Mexican territory now lies in the
unintentional spread of fruit-fly pests by uninformed travelers who
may carry infested fruits upon their persons or in their baggage.

The Mediterranean fruit fly (fig. 1) is one of the recently introduced
pests of Hawaii. It has found climatic and food conditions so favor-
able that at present there is not a family unaffected by its ravages.
It is doubtful if there exist in any other place in the world conditions
so favorable to the rapid spread and thorough establishment of this
pest as those in the Hawaiian Islands.

1 “The Mediterranean Fruit Fly in Hawaii,” E. A. Back and C. E. Pemberton, Department of Agri-
culture Bulletin 536. ( Ceratitis capitata Wied.)

2“The Melon Fly in Hawaii,” E. A. Back and C. E. Pemberton, Department of Agriculture Bulletin
491. (Bactrocera cucurbitae Coq.)

3 “The Melon Fly,” E. A. Back, C. E. Pemberton, Department of Agriculture Bulletin 643.

Nortre.—The manuscript of this paper was prepared for publication as a Farmers’ Bulletin, but owing
to the fact that it deals with an insect which has not yet been introduced into the United States it was
considered more appropriate to issue it in the series of Department Bulletins.

103876°—18—Bull. 640——1

2 BULLETIN 640, U. S. DEPARTMENT OF AGRICULTURE.
DISTRIBUTION THROUGHOUT THE WORLD.

The Mediterranean fruit fly is a cosmopolitan pest. It has been
known to science for 100 years and during these years has spread
throughout the world, until to-day the North American continent
is the only large land area upon which it has not become established.
It first attracted serious attention in London, where oranges arriving
from the Azores were discovered to be badly decayed and wormy.
(See fig. 2.) It was recorded as a pest in Spain in 1842, in Algeria
in 1858, in Italy in 1863, in Sicily in 1878, and in Tunis in 1885. In
1889 it was first reported in South Africa. It became established
in the western part of Australia in 1897 and in the eastern part in

Fria. 1.—Adult male Mediterranean fruit fly. Greatly enlarged. (Howard.)

1898. In 1899 it was detected in Tasmania, in 1900 it was found
attacking the apricot orchards near Paris, France, and during 1901
it was reported from New Zealand and Brazil. Compere, in 1904,
found the pest in Egypt, and in Asiatic Turkey at Beirut and Jeru-
salem. Argentina was reported infested in 1905. Between 1909
and 1914 it was found in the eastern and western parts of Africa,
and in 1915 it was first reported from the Island of Madagascar.
During 1916 it caused serious damage to the orange, tangerine,
peach, pear, and apple crops of the Patras consular district of Greece.
It is claimed that this was the first time in 10 years or more that this
pest had been noticed in this district of Greece. The Bermuda
Islands became infested during 1865.

THE MEDITERRANEAN FRUIT FLY. 3
ESTABLISHMENT AND SPREAD IN HAWAII.

The presence of the Mediterranean fruit fly in the Hawaiian Islands
was first discovered at Honolulu on June 21, 1910, and by the fall
of that year the pest was well established in the Punchbowl district
of the city. By October, 1911, it was found on the Island of Kauai,
and by January, 1912, on the Island of Molokai and in the Kohala
district of the Island of Hawaii (see fig. 3). During March, 1912,

Fic. 2.—Longitudinal section of grapefruit showing destruction of pulp caused by larve of Mediterranean
fruit fly. (Original.)

the Kona district was found infested, and by May of the same year
the fruit fly was discovered for the first time on the Island of Maui.
The towns of Naalehu and Hilea of the Kau district of Hawaii were
infested by March, 1913, and by the early months of 1914 infesta-
tions were found in the Hilo and the Hammakua districts of the same
island. By July, 1914, or four years after its first discovery at Hon-
lulu, the pest had spread to every important island of the Territory
of Hawaii and to-day is well established in every village and wild
guava scrub.

BULLETIN 640, U. S. DEPARTMENT OF AGRICULTURE.

+

HOW THE FRUIT FLY GOT INTO HAWATIL.

A number of popular accounts tell how the Mediterranean fruit

fly became established in Honolulu, but they are without foundation.

“AY VINA URoUVLIe}IPOW Of} JO WOTINGIAISTp OY} UL LayJOUG 9UO 0} UOT}LTOL PUB UOFFISOd OATYLIOI ITO} SULMOYS spuRIS]T ULITVALT Jo deW—e “p17

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SANVISI NVIIVAVIL

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Establishment came as a natural sequence of the development of
rapid ocean travel and cold storage, aided by unusually favorable

shore conditions about the harbor of Honolulu.

Hawaii was in no

Before that year ships touching

danger of infestation until 1898.

THE MEDITERRANEAN FRUIT FLY. 5

at Honolulu plied between countries not infested by this pest. East-
ern Australia was not infested before 1898. With the development
of rapid ocean transportation and cold storage on ships, the Medi-
terranean countries were enabled profitably to export oranges to
Australia, and it was in these shipments of fruits that the fruit fly
reached Australian shores and became established about Perth and
Sydney.

Establishment in Hawaii at Honolulu followed naturally the com-
mercial jump of the pest from the Mediterranean countries to Aus-
tralia. Honolulu is a port of call for ships plying between eastern
Australian ports and San Francisco and Vancouver, and the voyage
of about two weeks required for passage from Australia to Honolulu
is through a tropical climate permitting rapid development of the
fruit fly. No one ever will know just how the pest reached Honolulu
on these vessels from Australia, but in view of the rigid inspection
service of the Hawaiian Board of Agriculture it seems probable that
larve falling from infested fruits in the ships’ stores—in those days
often kept on deck—transformed to the winged adult stage by the
time of arrival at Honolulu. From 7 to 10 years ago trees bearing
fruits in which the fruit fly could develop grew in greater abundance
within a stone’s throw of the docks than at the present time and
offered an excellent breeding place for stray adults flying from the
ships during the time these were in port. There is probably no
port in the world where conditions were so favorable for the estab-
lishment of this particular pest as was that of Honolulu 10 years ago.

LOSSES INCURRED THROUGH THE FRUIT FLY.

The economic importance of the Mediterranean fruit fly as a pest
of fruits varies with the climate of its natural abode, or habitat.
Thus, in France, near Paris, where it has been known to attack
apricots and peaches, it has not become a serious pest, because of
climatic checks. Such checks to the severity of its attacks have been
noted in portions of Australia, South Africa, and elsewhere, and
would be operative in continental United States except in portions
of California and the Southern States. On the other hand, in tropical
and semitropical countries the fruit fly is capable of becoming a pest
of first importance, and, as in the Hawaiian Islands, may be classed
as the most important insect pest to horticultural development.

Practically every fruit crop of value to man is subject to attack by
this fruit fly. Not only is it of importance as a destroyer of fruit,
but it is the cause of numerous stringent quarantines which cost
the State and Federal Governments much money to make effective
and which rob countries of good or prospective markets for their
fruit. Fortunately, it has been found that the Chinese banana and
the pineapple, the two most valuable species of fresh fruits formerly

6 BULLETIN 640, U. S. DEPARTMENT OF AGRICULTURE.

exported from Hawaii, offer so little danger as carriers of the Med-
iterranean fruit fly, when they are packed for shipment, that this
part of Hawaii’s export trade in fresh fruits with the coast may still
be carried on, provided the inspections of the Federal Horticultural
Board now in force
are continued. The
necessary quaran-
tines against all other
host fruits, however,
particularly against
such fruits as the avo-
cado and mango, has
had, and will continue
to have, a serious ef-
fect upon _horticul-
tural pursuits and the
development of the
small farmer.

At present the in-
festation of edible
fruits in the coastal
regions of Hawaii is
general and about as
severe as could be ex
pected. The work of
the Mediterranean
fruit fly, with that of
the melon fly, has put
a most serious check
upon the horticul-
tural development of
the islands just at a
time when this devel-
opment was gather-
ing strength. In
South Africa the
Mediterranean fruit

Fic. 4.—Apples destroyed by larvee of Mediterranean fruit fly. Al- fly 1S regarded as one

though an apple externally may appear normal aside fromthe dark of the greatest draw-
spots where thefemale fly punctured the skin in laying her eggs, the le hi 1
pulp is often found badly decayed and eaten out by the maggots, bac s to the deve Op-

as shown in the lower fruit. (Original.) ment of the fruit in-
dustry in Cape Colony, where, it is stated, during certain favorable sea-
sons large areas of apricots, figs, pears, plums, apples (fig. 4), and
quinces are almost all affected. Many instances of damage to citrus
and other crops in southern Europe, South America, Africa, and Aus-

: THE MEDITERRANEAN FRUIT FLY. 7

tralia might be added to impress one unfamiliar with the ravages of this
pest that it is one that can not be trifled with. The amount of
damage which would result through the introduction of this fruit
fly is so great that every effort should be taken to prevent its estab-
lishment in new terri-
tory.

WHAT THE MEDITERRA-
NEAN FRUIT FLY IS
LIKE.

The adults.—The
Mediterranean fruit fly
is an insect that in the
adult stage resembles in
size and general shape
the ordinary house fly,
but differs greatly in the
color pattern of the
body and wings and in
its habits. In figure 5
three adults may be seen
attempting to lay eggs
inanorange. The glis-

ine bl Fig. 5.—Three adults of the Mediterranean fruit fly on a sweet
tening b me spots ooo orange. About two-thirds naturalsize. (Authors? illustration.)
the insects’ back, the

two white bands on the yellowish abdomen, and the yellow and
black markings of the wings at once distinguish this fruit fly from
all other insects in Hawaii. The colors, brown, yellow, black, and
white, predominate and form a pattern that can be recognized easily
after comparison with the drawing of the
adult fly (fig. 1).

The eggs.—The female fly is able to
drill, with the sharp end of her body, small
pinhole-like breaks or punctures in the skin
of fruits, and through these punctures she
lays her eggs. Naturally, these egg punc-
tures are so small that they are not seen
by the average person. Ordinarily the fly
Fic. 6.—Cross section of a smallapricot lays from one to Six eggs through these

showing eggslaid through skinin five holes into a small cavity made for them
places. (Authors’ illustration. ) : . .

just beneath in the pulp or rind. In

some instances several hundred of the small white eggs, which

are only about one-twenty-seventh of an inch long and shaped as

those illustrated in figures 6, 7, and 21, may Bi ae in a single

103876°—18—Bull. 640——2

8 BULLETIN 640, U. S. DEPARTMENT OF AGRICULTURE.

egg cavity as the result of repeated egg laying by many females
through the same opening in the skin.

The larve.—The eggs hatch into whitish larve, or maggots, that
burrow or tunnel in all directions through the pulp, feeding as they
go and causing decays to start.
When first hatched they are very
difficult to detect, but when full
grown they are very white and,
although only four-sixteenths to
five-sixteenths of an inch long,
are quite easily seen. Full-grown
maggots have the peculiar habit, if
taken out of the fruit and placed
upon a smooth surface, of curling
up and jumping from 1 to 6 inches.
For the general appearance of
the larve see figures 8 and 9, a.
Fig. 7.—Cross section of peach showing general The Ws upe.—After leaving the

shriveling of walls of egg cavity and separation fruit upon which they have fed,
oops. raving mad oe and metal 5 the larvae either burrow into the
soil to depths varying up to 2

inches or seek shelter under any object upon the ground and there
transform to the pupa or chrysalis stage. Durmg this stage the
insect is not able to move and re-
sembles the seedlike object illustrated
in figure 9, 6. Although outwardly
appearing quite dead, inwardly the
wonderful changes are taking place
by means of which nature transforms
the ugly maggot into the beautiful fly;
and in the course of a few days the
adult fly breaks forth from the pupa,
pushes her way up through the soil,
and, as the mother of a second gen-
eration, flies back to the tree and
searches for fruits in which to lay her

eggs.

INTERESTING FACTS ABOUT THE ADULT FLY.

Incapable of inflicting bodily injury
on man, the adult fly is, nevertheless,

; : A Fic.8.—Small mango fruit cut toshow white
the fruit growers’ most persistent — larve or maggots of Mediterranean fruit

enemy in Hawai, for she is contin- —“4y_and “damage aay

: = : > (Severin.)
uously searching for fruits in which

to lay her eggs. Adults die within three to four days if they have

THE MEDITERRANEAN FRUIT FLY. 9

no food; but if they can secure the juices of fruits or the honeydew
of insects, which form the bulk of their food, they may live long
periods. ‘Two flies lived for 230 and 315 days, respectively. But asa
rule life is much shorter, although many live to be four to six months .
old. Many die when they are very young, even if they have had food.

In Honolulu females begin to lay eggs when 4 to 10 days old,
and, like hens, only much more faithfully, continue to develop and
lay eggs in fruits almost daily so long as they live. A female may
lay on an average from 4 to 6 eggs a day, 22 eggs being the largest
number known to have been laid by a fly during any one day. On 10
consecutive days one fly laid 8, 11, 9, 6, 8, 3, 3, 3, 3, and 9 eggs;
another laid 0, 5, 14, 8, 13, 10, 6, 4, 4, and 0 eggs. The largest
number of eggs laid during life by a single female kept in the labo-

Fic 9.—Mediterranean fruit fly: a, Larve, of Oneear b, pupe, or chrysalids. Twice naturalsize.
riginal.

ratory was 622. This fly lived only 153 days. It is probable that
800 eggs, or even more, may be laid by single hardy females under
favorable conditions.

It is also important, from the standpoint of control, to know that
females deprived of a chance to lay eggs in fruits for a period of four
to six months when certain crops are not in season have the power
to begin depositing eggs as actively as younger flies when fruits
sufficiently ripe become available for oviposition. Thus one female
kept in the laboratory for the first five months of her life without
fruits in which to lay eggs laid 11, 4, 9, and 9 eggs durmg the first
four days of the sixth month of her life when fruits were placed in
the cage with her.

CLIMATIC CONDITIONS FAVORING RAPID INCREASE IN HAWAII.

The time required by the fly to pass through the egg, larva, and

pupa stages depends very much upon the climate. The climate of
Honolulu and of the coastwise regions of Hawaii in general is very

10 BULLETIN 640, U. S. DEPARTMENT OF AGRICULTURE.

favorable to fruit-fly increase. At Honolulu the temperature rarely
drops as low as 58° F., and then only for a few hours during one or
two nights in the year.
The daily range in
temperature is small,
averaging between 8
and 11 degrees, while
the normal monthly
mean temperatures
range between 70.9° F.
in the winter and 79°
F. in the summer.
Biological work has
shown that even the
lowest monthly means
of localities up to 1,500
feet elevation have lit-
tle effect upon the fruit
fly other than to retard
somewhat its develop-
ment. Itis never cold
enough throughout the
coastal regions of Ha-
wail to render either
the adults or the larvee
inactive. There are
no periods of the year
at any Hawaiian port
when climatic condi-
tions are unfavorable
for fruit-fly increase.
A continuous temper-
ature of 58° to 62° F.,
or the lowest range of
temperature usually
experienced, does not
increase. the normal
mortality among the
larvee.

LENGTH OF TIME REQUIRED
FOR DEVELOPMENT.

During the warmest
Hawaiian weather,

Fig. 10.—Threeimportant ediblefruits subject to fruit-fly attack:
a, Strawberry guava; b, loquat; c,star apple. These are grown also
for their ornamental value. (Original.) when the mean tem-

perature averages about 79.5° F., the Mediterranean fruit fly requires
as few as 17 or as many as 33 days to pass through its immature stages.

THE MEDITERRANEAN FRUIT FLY. tT

At this season by far the larger number pass through these stages
in 18 to 20 days. At an average mean temperature of 68° F., which
is about the coolest temperature in Hawaii where fruits are gener-
ally grown, the immature stages require 40 to 69 days.

Just what the length of the immature stages may be in cooler
regions can not be definitely stated, but experiments indicate that it
may be considerably increased. The egg stage has been increased
from a normal of 2 days at Honolulu in summer to 25 days by the
application for 22 days of a temperature of 48° to 53° F. A well-
grown larva survived a temperature of 48° to 54° F. for 79 days.
A newly-hatched larva remained practically dormant for 57 days at
an out-of-door temperature ranging from 27° to 73° F. (mean 48°
F.), whereas in Honolulu during summer it would have remained in
this stage only 2 days. The fruit fly has been held in the pupa
stage for about two months at an out-of-door temperature ranging
between 38° and 72° F. (mean, about 54° F.). Had the mean been
about 79° F., it would have remained in the pupa stage only 9 to 11
days. Three larve in very firm apples required 28, 58, and 74 days
to become full grown and leave the fruit to pupate at Kealakekua,
where the temperature ranged between 58° and 80° F. (mean, about
68° F.). Add to the 74 days required for larval maturity 4 days
for the egg stage and 20 days for the pupa stage, and one has 98
days, or over three months, as the time required for the fly to pass
through the immature stages under certain host conditions at a
mean of 68° F. Thus while these stages may be completed in as
few as 17 days, three to four months is a very conservative estimate
for possible length under less favorable climatic conditions, or a
period sufficiently long to outlast the coolest seasons of the
semitropics.

FRUITS, NUTS, AND VEGETABLES ATTACKED.

The Mediterranean fruit fly is particularly injurious because it
attacks so many more different kinds of fruits of value to man than
does any other known fruit fly. In the Hawaiian Islands 72 kinds
of fruits have been found infested. Fortunately, the pineapple is
not infested, and the banana is free from attack when shipped under
commercial conditions. The fruit fly has been reared from the
following fruits: Fruits that are heavily or generally infested are
marked (1), those that serve quite often as hosts or of which many
escape infestation are marked (2), and those rarely infested are
marked (3).

12 BULLETIN 640, U. S. DEPARTMENT OF AGRICULTURE.

List of host fruits of the Mediterranean fruit fly.

SCIENTIFIC NAME, COMMON NAME.
1. Achrasisapotays)... 2. 4-2 Sapodilla.
2. Acordulsp(3):. 2-2 hee eee Acordia.
35 -ANONG MUTICOtON(2) =. - = ee eee Sour sop.
4. Arengia saccharifera (3)......-.------- Sugar palm.
5,. Arioranpia means) 2s os. Seee eae Breadfruit.
6. Averrhoa carambola (2)........-.----- Carambola.
7. Calophyllum inophyllum (1)....-..---- Ball kamani.
8. Capsicum sp.(2). oo. 4 oven ae cae Bell peppers (fig. 17, p. 19).
9. Carica pandya (2)-252 3-22. - - eee Papaya.
10. ‘Carica: quiercifoun (22 ee. 3. 2 oes Dwarf papaya.
1). Osrwsa.ardutng (2 ys. LEST ore ae Carissa (fig. 11, h).
12... Castmeron edulis (Wrsso2 .4 . ns Peer Sapota.
13.. Cestrtncaps (2)> < eoee ea soe sae Chinese inkberry.
14. Chrysophyllum cainito (1). ....------- Star apple (fig. 10, c).
15. Chrysophyllum oliviforme (1)..-.-.-.---- Damson plum (fig. 11, d).
16:Chrysophylhum sp qi)it. 2 eae Biees Chrysophyllum.
7%; (Citrus gaponica (1) Nar oie Se Chinese orange (fig. 18, p. 20).
18:;, Crtrus gaponicag) scene pees eys Kumquat.
197. Carus obs) nee aes Tangerine.
20; Oats 9000S)... 50 eee ee Mandarin.
21. Citrus medica limetia (1)... .------=-- Lime.
22. Citrus medica limonum (1)..........-Lemon (fig. 19, p. 21).
DOE OUUSIOECHANGTLGN ()=yai= ee ee ee eee Grapefruit (figs. 2, 20, 21, 22, pp. 3, 22,
and 23).
DA» Oiiriie HEC GTI! CD) ys 2 eres, eee Shaddock.
25. Citrus aurantium (1)...............-Sweet orange.
26. Citrus aurantium var. amara (1). ....-Sour orange.
OTS Claisena Wan py (3). See. eee = Wampi.
28:: Cofeajsnabtca (Se eek oe oe Coffee (fig. 11, b).
99. Cafica Liberten (1) ne iss yt © = eee Liberian coffee.
30, Cydonin-oulganis| (ee ecco. asec e oe Quince.
3)... Diospyros decandra (A) a. . eee esse Persimmon.
32. Eriobotrya japonica (1).............-Loquat (fig. 10, b).
33.) Lugenia brasiliensis Gl)... . oh. = semen Brazilian plum or Spanish cherry.
34. Eugenia ambos Cl) o222...4 Ja: eheeee <2 Rose apple (fig. 11, g).
35: ugenia michelin) cle = tee eee Surinam cherry.
36. Eugenia uniflora (1)............------ French cherry.
Ss ECCS CPICE AON set ee. cin ae ee re ee Fig.
38. Garcinia mangostana (2).........----- Mangosteen.
39. Garcinia xanthochymus (2).........--- Mangosteen.
40; GossypiumeppZ)- 22 sche b-cl ye: fee Cultivated cotton (fig. 11, é
41. Jambosa malaccensis (2)...........--- Mountain apple.
42. Lantanis placuachulla (3)..........-- Palm.
43. Lycopersicum esculentum (2)........-- Tomato.
44, Litchwciinensis \(3)2 22.) ee oe Lichee nuts (fig. 11, ¢).
Ab. Mangifera indwaG). . ic. 22: ss ee Mango (figs. 8, 24, pp. 8 and 25).
AG... Mamusops elengt (1) o5.<..-25.-2-<250e8 Elengi tree (fig. 11, 7).
a7 :. Maurrayaétonies (Gi) 2: eee tes Mock orange (fig. 11, /).
48, Musa spp: (3). ...--2....:...6.....-<Banane (fessieend fia saeee
49, Noronhia emarginata (3)............- Noronhia.

50. Ochrosia elliptica (2)...-5..552% eee Ochrosia,

THE MEDITERRANEAN FRUIT FLY. 13

Fig. 11.—Ornamental trees and shrubs grownin Hawaiithat support the fruit fly. Itis useless to protect
edible fruits when ornamentals are allowed to grow near by that harbor the fruit {1 y: a, The bestill,
showing drops of white sap that exude when the fly punctures the skin: b, a coffee cherry sectioned to
show the maggots feeding on the pulp; c, the lichee nut is not attacked by the fly unless the outer skin
has broken; d,a damson plum, showing an adult fly caught in the sticky sap; e, a cotton bollinfested
by the pink bollworm and the fruit fly; f, a cluster of mock-orange berries; g, arose apple sectioned to
show fruit-fly attack; h, the Carissa, showing drops of white sap that have exuded from punctures made
in theskin by the fruit fly; i, theelengi berries, that develop many fruit flies,

14 BULLETIN 640, U. S. DEPARTMENT OF AGRICULTURE.

Sl Onuntiusulgaris 22ers. ore Prickly pear.
52. Passifiora'sp. (3).-..--. - OED B82 Passion vine.
5S. Perseagratssuma (2)2..2- 2-62 -snee Avocado (fig. 13).
54. Phoenws dactylafera (3)... -2.2-.-~ ae Date palm.
55. Psidium cattleyanum (1)... ---------- Strawkerry guava (fig. 10, a). -
56. Psidium guayava (1)......------------Sweet red and white lemon guavas.
57. Psidium guayava pomiferum (1)------- Common guava.
58. Psidium guayava pyriferum (3)... ..--Waiawi.
59. Prunus persica (1)...-.-..--.-----+---Peach (fig. 7, p. 8).
60. Prunus persica var. nectarina (1)... .-- Nectarine.
61. Prunus armeniaca (1).....----------- Apricot (fig. 6, p. 7).
62: PrangRpp eset. .' <i: ass Plum.
63. Punica granatum (3)... -.-.---.-------Pomegranate.
64. Pyrus'sppe(. ero Saran aso Apple (fig. 4, p. 6).
65. Pyrus spp Cee a Mt. = 3s ee Pear (fig. 12).
66. Solanum melongena (3)...----------- Eggplant.
67. Spondias dulcis (3): Bee -- - =~ --Aeee Wi.
68. Terminalia catappa (1)...-..-.-.----- Winged kamani or tropical almond.
69. Terminaha chebula (V).22.....-. as. Natal plum.
70.. Thevetia neriifolia (1)-.-...-2-. -.Baees Bestill (fig. 11, a).
TS Wits 1OOCW ete (S).2 lacs y ee eee Grape (fig. 25, p. 26).
72. Santalim freycinetianum var. littorale
[G) Rpeere es Fo8 = ok Beach sandalwood.

This list shows that practically all the ordmary useful and edible
fruits in Hawaii are infested heavily. Thus peaches can not be grown
at present, for they are ruined before they become well grown; Chi-
nese oranges (fig. 18), tangerines, figs, loquats (fig. 10, 6), rose apples
(fig. 11, g), many varieties of mangoes (figs. 8, 24), certain avocados
(fig. 13), guavas (fig. 10, a), coffee cherries (fig. 11, 6), star apples
(fig. 10, ¢), sapotas, persimmons, apples (fig. 4), pears (fig. 12),
plums, nectarines, and quinces—all these are badly infested. On the
other hand, a large percentage of the ripening fruits of the tomato,
prickly pear, mangosteens, mountain apples, and wampis are free
from attack, although certain fruits may be at times heavily infested.
When tomatoes are wormy, the melon fly, and not the Mediterra-
nean fruit fly, is usually the msect domg the damage. Ordinarily,
sweet bell peppers are not generally infested, and cotton bolls be-
come infested only after they have been damaged by some other
insect (figs. 17 and 11, e).

The pomegranate, breadfruit, eggplant, wi, grape (fig. 25), date,
certain seeds of palms, lichee nuts (fig. 11, ¢), and the Chmese mk-
berry are very rarely infested, even in Honolulu. For practical pur-
poses they may be said to be immune. Lichee nuts ripening on the
tree become infested only when the outer shell breaks, thus exposing
the white pulp to attack.

Hawaiian rruits, nuts, and vegetables not listed are free from
attack.

THE MEDITERRANEAN FRUIT FLY. 16

ORNAMENTALS SERVING AS HOSTS.

Not only does the Mediterranean fruit fly attack the ordinary
cultivated fruits, but in Hawaii it has shown a preference for the fruits
of many ornamental trees and shrubs. Thus the nuts of the winged
kamani, the ball kama-
ni, the rose apple, dam-
son plum, star apple,
Brazilian plum or Span-
ish cherry, the Surinam
and French cherries,
the berries of the mock
orange and elengi tree,
the fruits of the Natal
plum, and the mature
fruits of the bestill are
allusually well infested.
Even the fruits of cer-
tain palms and the
beach sandalwood may
harbor the fly. Orna-
mentals less subject to
attack may be found in
the foregoing complete
list.

HOST FRUITS OF COM-
MERCIAL VALUE.

PINEAPPLES.

Many experiments
have been carried on to
determine whether the
Mediterranean fruit fly
can live in the pineap-
ple. It has been found Fic. 12.—Bartlett pear, the pulp of which has been entirely eaten
that even under forced out by the maggots of the Mediterranean fruit fly. The fruits

laboratory conditions often remain on the tree and shrivel up after they have been
ruined. (Authors’ illustration.)

the fly can not live or
mature in green or ripe pineapples. No person has ever found a
pineapple infested by this pest in Hawaii.

PAPAYAS.

The papaya is one of the commonest plants about Honolulu. Its
fruit is the universal breakfast fruit. Probably not one person in a
thousand in Honolulu, however, knows that papayas become infested.

Unless the fruits are allowed to remain upon the trees until overripe,
103876°—18—Bull. 640-3

16 BULLETIN 640, U. S. DEPARTMENT OF AGRICULTURE.

the fruit fly can not mature in them. The milky juice, which exudes
copiously from breaks in the skin of the fruits up to the time when
the fruits can be cut
for ripening in the
house, contains a di-
gestive principle that
is fatal to the eggs
and larve of the fly.
This juice protects
the fruits from infes-
tation when imma-
ture. But as the
fruits become over-
ripe, and also unfit
for the table, the juice
flows less abundantly
from breaks in the
skin made by the fly
when she attempts to
lay her eggs, and the
eges which she then
lays canmature. As
many as 205 flies have
been reared from sin-
gle overripe fruits.
So while the papaya
is a host fruit, it is
practically never in-
fested until too ripe
or otherwise unfit for
the table.

AVOCADOS.

With the exception
of one or two early
varieties, the infesta-
tion of the avocado
is so obscure that the
general belief prevails

Fic. 13.—Avocado. This valuable fruit of California and Florida is 10 Honolulu that this
subject to infestation in Hawaii. In this instance the maggots are fruit is free from is
working at the stem and blossom ends. (Authors’ illustration.)

tack. The Guate-

mala, or nutmeg, variety is the only one free from attack when growing
uninjured. Theskin of allothervarieties, whether thin or of usual tough-
ness, can be punctured by the adult fly, as proved by many examinations
of fruits. The avocado, like the ordinary pear, is best when picked

THE MEDITERRANEAN FRUIT FLY. EG

i

+

2 eT pa een a TE RA anne SRT

Fic. 14.—Cooking banana of the Popoulu variety taken from tree in an infested condition. Note small
round holes in the skin through which maggots left the fruit when they became full grown. (Authors’
illustration.)

Fic. 15.—Cooking banana of the Moa variety cut to show destruction of pulp by maggots of the Medi
terranean fruit fly. (Authors’ illustration.)

18 BULLETIN 640, U. S. DEPARTMENT OF AGRICULTURE.

while still hard, though mature, and allowed to soften in storage.
With most varieties it is not until the fruits are mature enough for
gathering or dropping that adults lay eggs in them. Many fruits
upon the market are not in the least affected. While avocadoes are
not usually a favorite host for the fly, they are sufficiently infested
to warrant the quarantine prohibiting the shipment of them to the
mainland. (See fig. 13.)
BANANAS.

Experimentation during the past four years in Hawaii has proved
that the Chinese banana! and the Bluefields banana? are prac-
tically immune from attack if harvested and shipped to the coast in
accordance with the demands of the trade and the Federal Horti-

Fic. 16.—Loss to coffee-mill owners due to infestation of coffee cherries by Mediterranean fruit fly.
Coffee beans to left pulped from uninfested cherries; beans to right pulped from infested cherries.
Cherries failing to pulp, because infested, appear as black; pulped beans are grayish white. (Orig-
inal.)

cultural Board. Persons wishing the results of careful experimental
work used as a basis for these conclusions may obtain them in
printed form by applying to the Bureau of Entomology. The
immunity of commercial varieties of bananas has been shown to be
due to the fact that neither the eggs nor the newly-hatched larve
can survive in the tannin-laden peel of the green though mature fruit.
Indeed, the copious and sudden flow of sap from egg punctures made
by the female fly in unripe bananas renders the successful placing of
eges in such fruits difficult and rare.

No fruits of the Chinese variety ripening prematurely on bunches
in plantations have been found infested. But of the cooking bananas,
fhes have been reared from the ripe and yellowish fruits of the thin-
skinned Popoulu variety (fig. 14) growing in the field, and from the

1 Musa cavendishii. 2 Musa sapientum.

——

THE MEDITERRANEAN FRUIT FLY. 19

well-grown though green-colored fruits of the Moa variety, the peel
of which had become cracked, thus causing a break in nature’s normal
protection to the pulp. Figure 15 is a cross section of a Moa banana,
showing the tunnels made through the pulp by the larve, and the
darkened decayed areas about the tunnels. Adults have been reared
also from another variety of cooking bananas.

Because flies have been reared from cooking bananas, it is not
considered safe to permit their export to the coast, and they have
been placed on the
list of quarantined
fruits by the Federal
Horticultural Board.
The Chinese and Blue-
fields bananas may
still be exported from
Hawaii, provided
they are grown and
inspected before ship-
ment in accordance
with Federal regula-
tions. So far as is
known, the “apple”
and the ‘ice-cream”’
bananas common in
Hawaii are not. in-
fested.

COFFEE.

Coffee cherries as
they ripen are favor-
ite hosts of the Medi-
terranean fruit fly.
Fortunately, the
larvee attack only the

pulp surrounding the

.17.—S 1 infes I i fruit-fly 1 -
beans or seeds, and — 17 were dell pepper infested oy Mediterranean Tuit y arvee
5 Note that the upper right-hand portion of fruit has decayed as a
im no way affect the result of attack. This decay later extends to all parts of the fruit.

value of thelatter (see = (Omisinal.)
fig. 11, 6). Chemical analyses of beans from infested and uninfested
cherries, tasting tests of coffee made from similar roasted beans, and
weighings made of dried beans have failed to reveal any ill effect to
the beans themselves due to fruit-fly attack.

The unrestricted development of larve within coffee cherries,
however, does bring about certain losses to the grower and mill
owner. Before parasites were introduced cherries became infested

~,

os
™~ ~

20 BULLETIN 640, U. S. DEPARTMENT OF AGRICULTURE.

as soon as they began to turn white from green in the final ripening
process, and the larvee, numbering from 2 to 8, were able to become
nearly full grown by the time the cherries had turned red. The pulp
surrounding the beans varies from two to seven fifteenths of an inch
in thickness, or is scarcely thicker than the well-grown larva of the
fruit fly (see fig. 30, p.39). Therefore, by the time the cherry is ordi-
narily ready for harvesting, the larvee have devoured practically all
the pulp, leaving the seeds hanging more or less loosely within a
sack comprised of the thin skin of the cherry. If the weather
happens to be dry, the skin shrivels and hardens about the beans
and the cherry remains on
the branch indefinitely and
resembles those killed by
disease. However, should
the harvesting season be_
rainy, the skin decays rap- |
idly, and under the weight
of the beans the cherry falls
to the ground. Aslight jar
may at such times cause
many cherries to fall to the
ground, where they are
lost. This type of loss ne-
cessitates extra pickings
and greater cost for labor.

Since the successful intro-

Fic. 18.—Chinese orange sectioned to show damage by Medi- duction of parasites the
terranean fruit fly. Chinese oranges, kumquats, tanger~ . :
ines, satsuma oranges, and many limes are easily and gen- fruit fly has been so re-

erally infested because of their loose peel and lack ofa thick duced in the coffee field

SEE may! eo that the infestation of
cherries occurs so late in the ripening process that extra pickings
are not necessary, and the cherries on reaching the pulping mills
during the height of the harvesting season contain chiefly eggs
or young larve which have not had an opportunity to reduce the
pulp.

Badly infested cherries do not pulp as readily when run through
the pulping mill, and naturally weigh much less than sound cherries.
(Fig. 16.) The loss in number of cherries in a given weight of badly
infested fruit has been found to vary at times from 27 to 59 per cent.
This loss in weight, which takes place only in the worthless pulp, and
in no way affects the bean, which alone is of commercial value,
brought about a financial loss to growers who sold their fruit by
weight according to prices obtained before the fruit fly was intro-

-

THE MEDITERRANEAN FRUIT FLY. 21

duced. This has been appreciated and has caused a readjustment of
prices paid for coffee “in the cherry” and has been responsible for
the erection of many small pulping mills throughout the Kona coffee
district.

It seems reasonable to believe that the remarkable success of
introduced parasites in checking the infestation of coffee will free the
coffee grower from fur-
ther worry so far as the
Mediterranean fruit fly
is concerned.

CITRUS FRUITS.

While all citrus fruits
are favorite hosts of the
Mediterranean fruit fly,
certain of them are
found to contain larvee
more often than others.
No citrus fruits are too
acid for fruit-fly devel-
opment. lLarve have
been reared from the
sourest lemons. Adult
flies are fond of laying
eggs in large numbers
in all citrusfruits. Thus
13 punctures in one
grapefruit contained
#6) 153, 32; 25, 18, 8,
46, 113, and 9 eggs, re- ae
sp ectively. Thir ty-nine Fic. 19.—Lemons of commercial varieties have never been found
oranges, either yellow with larvae of the Mediterranean fruit fly destroying the pulp

unless they have had the rind cut or broken previous to attack.

or orange In color, con- The adult flies may puncture the skin and lay eggs, as indicated
tained an average ot 32 by the discolored spots, but the eggs and larvze die in the peel.

: (Original. )

egg punctures, with a
maximum of 108 and a minimum of 7 punctures. In 50 ripe lemons
1,422 eggs were laid in 185 punctures. Yet no adult flies developed
from this grapefruit or from the oranges and lemons. On the other
hand, well ripened Chinese oranges (fig. 18), thin-skinned limes, kum-
quats, and tangerines are so generally infested with larve in the
pulp before they become well ripened that they are always regarded
with suspicion.

Although many eggs are laid in lemons, it is rare that lemons
are found with maggots in the pulp even when the fruits are so ripe

‘

Fic. 20.—Ripe grapefruit showing copious gummy secretions that
may, though more often do not, follow attack by Mediterranean fruit
fly. (Original.)

nese oranges the peel is so thin that the fruit

BULLETIN 640, U. S. DEPARTMENT OF AGRICULTURE.

that they fall to the
ground. Why, then,
are Chinese oranges
and tangerines easily
infested with larve
in the pulp whereas
lemons, grapefruit,
and oranges ward off
fatal attack either
entirely or until after
they are overripe ?
The reason is that
a great mortality oc-
curs among the eggs
and newly hatched
larvee in citrus fruits
having a thick peel-
ing or rind. In Chi-
fly can lay her eggs

through it into the pulp itself or between the pulp and the rind,

so that the larve on hatching can at once begin
to feed on the pulp. As a result the pulp of
the Chinese orange (fig. 18) is almost always
infested with larve. The case is different with
lemons (fig. 19), grapefruit (fig. 20), and ordi-
nary seedling oranges. In these fruits the peel
is so thick that the fly must deposit her eggs in
the outer part of the white rag as illustrated in
figure 21. In making the puncture she often
ruptures an oil cell in the rind, and the oil thus
liberated kills the eggs. But if the eggs are laid
between oil cells, the young larve have difficulty
in making their way through the rag to the pulp,
and a very high percentage of them die in the
attempt.

Then, too, a gall-hke hardening develops quite
rapidly about the egg cavity in oranges, grape-
fruit, and lemons, as indicated by the darkened
area about the egg cavity in figure 21. This
hardening often makes of the cavity a prison
from which the young larve can not escape and
in which they are literally starved to death.

It thus happens that the larve that succeed
in entering the rag of the peel from the egg
cavity are able to reach the pulp of grapefruit

Fia. 21.—Section of grapefruit
rind, showing two egg cavi-
ties, one in cross section.
Drawing made one week af-
ter fruit was picked. Note
conical elevation about egg
cavities left by withering of
rind; also thickened walls of
egg cavity and single larval
channelintherag. ( Authors’
illustration.)

THE MEDITERRANEAN FRUIT FLY. 23

and oranges in astonishingly small numbers because of the imper-
viousness of the rag. It is the persistent attack of successive families
of larve hatching from different batches of eggs laid in the same
punctures that finally breaks down the barrier between the young
larve and the pulp. A fuller discussion of the infestation of all citrus
fruits may be had on application to the Bureau of Entomology.
Regardless of what has just been stated concerning the great
mortality that occurs among the eggs and young larve in the rind

Fic. 22.—Cross section of grapefruit to indicate difficulty of always telling from exterior appearance of a
fruit that maggots are eating out the pulp. (Authors’ illustration.)

of grapefruit, oranges, and lemons, adult flies have been reared from
them all. Lemons, however, have never been known to be infested
in the pulp unless the rind has first become broken by thorn pricks,
decays, or in some other mechanical manner. And in spite of the
fact that oranges and grapefruit may become very wormy, as illus-
trated in figures 2 and 22, they are usually uninfested in the pulp,
and are fit for table use if they are gathered as soon as they ripen.
But if citrus fruits were grown commercially in Hawaii in large

94 BULLETIN 640, U. S. DEPARTMENT OF AGRICULTURE.

orchards as they are in Florida and California, and were severely
attacked as they are in Hawaii to-day, they could not be shipped
profitably, for, although they might not contain larve within the
pulp, the many breaks in the rind made by the flies while laying eggs
would make possible the entry of various molds (see fig. 23) that

Fia. 23.—Orange injured by Mediterranean fruit fly. Each black spot represents a place where the fruit
fly has punctured the rind to lay eggs, but the maggots were not able to eat through the peel, and died.
About the injured spot decays have started which at first affect only the peel. Blue mold growsrapidly
in these injured spots. (Original.)

would cause unprecedented decays while the shipments were en route
to market.

ARTIFICIAL METHODS OF CONTROL NOT SATISFACTORY UNDER
HAWAIIAN CONDITIONS.

It is unfortunate that the satisfactory methods of control used
against the Mediterranean fruit fly in several other countries, par-
ticularly in portions of South Africa and Australia, have failed in
Hawaii. There are, however, several good reasons for such failures.
The great money-making crops of Hawaii at present are sugar, pine-
apples, rice, coffee, taro, bananas, and cattle. But sugar, pineapples,
and taro are not attacked by this fruit fly, and, as already shown,
coffee and bananas are not sufficiently attacked to injure their com-
mercial value. With one exception, including a small number of

THE MEDITERRANEAN FRUIT FLY. 25

avocados, no commercial orchards exist in Hawaii. Still there is
hardly a family, unless it be in the business section of Honolulu,
that does not grow a number of fruit trees, such as oranges, lemons,
papayas, peaches, avocados, limes, grapefruit, guavas, bananas, man-
goes, etc., that bear prodigally under normal Hawaiian cultural con-
ditions, and, until the advent of the fruit fly in 1910, formed a most
welcome addition to the food supply.

Much of the native-grown fruit that is sold in the local market is
grown on trees scattered here and there in dooryards and is in
excess of what the
owner needs. Practi-
cally no one depends
on growing fruit for
his living. No devel-
oped fruit industry
exists such as one
finds on the main-
land, andno moneyed
interest concerns it-
self with steps for
fruit-fly eradication.
In other words, there
are no impelling in-
centives to solidify
public opinion for the
consistent and coop-
erative use of artificial
remedial measures
that could be made
effective if their ap-
plication would yield
returns warranting

the expenditure.

The situation also 16.24.Improved mangosectioned to show havoc caused by maggots
of Mediterranean fruit fly. (Authors’ illustration.)

ismade more difficult
by reason of the large amount of vegetation, bearing fruits of little
or no value to man, that grows throughout the islands and that
can not be eradicated without the expenditure of prohibitive sums
of money.

But this great abundance of dooryard and wild host vegetation
has had such a vital part in the undoing of artificial control measures
and in the success of parasite introductions that it is worthy of fur-
ther attention. Aided by a favorable climate, it has made of Hawaii
a fruit-fly paradise that is not duplicated elsewhere on the earth.

26 BULLETIN 640, U. S. DEPARTMENT OF AGRICULTURE.
THE CAMPAIGN AGAINST THE FRUIT FLY IN HAWAII.
HOST CONDITIONS IN HONOLULU AND HILO.

The residents of Honolulu and Hilo are justly proud of their mag-
nificent vegetation and have taken great pleasure in growing an

Fig. 25.—This bunch of grapes, apparently perfect, con-
tains one berry that is decayed and contains a larva
of the Mediterranean fruit fly. The Isabella grapes
in Hawaii are seldom attacked, even in Honolulu,
yet they are likely to carry the fly to California.
(Original.)

unusually large assortment of trees and shrubs on their properties.
An inventory of such trees and shrubs in the portion of Honolulu
bounded by Liliha, Punchbowl, Beretania, and School Streets gave
a total of 4,610 that bore fruits in which the fruit fly can develop.

THE MEDITERRANEAN FRUIT FLY.

27

TaBE I1.—Number and species of host trees of the Mediterranean fruit fly growing in that
portion of Honolulu bounded by Liliha, Punchbowl, Beretania, and School Streets.

pepriceuse wit. te Ue. . ARs
Arocadomerart:: - pans Se gcal ee

CSET 72 RR ee a
Clomegaumcnerry —. -—.-----,.---s-
Wirncrpramnre =. ot
Coffee. . .
Coffee, Liberian .§: .22.2..........
CONS 0) See a enn ed ea See
(SUS 01 0) a
POAAMSON WW ee ete 2 ee ee a= os
LULL cS. . sscetelans Meelis te Ea eaanindbae
Guava common: 222. e011. oe:
Guava, strawberry. .......---- aus
DU Ee er
(Soa hl oe | a i a
amin, winged... «2065.2... ,-
UNO ues se oe est oe

vid yh ae ee

33

Masiene Ue? Sh elena.) 28
Wma ile ei atc apopek Ji avs eteite od sn 1, 154
Wit GMCeTE Ae ois. neha ae 7
Mountain apple. -2< 22.22/22. 41
Mock Omnteses-an oe) ec. ee ee 33
Rimnpe, sweenl. Soleil Avi ars! 372
Papanacsil am 95 Die ete 687
Oat A eee open) 5- Sar ak oa ep 69
iReanmubanrtlettess: see. ie: ae ee 2
POMEPTANATOS = Cor ec ee 128
840 2 AR a oi Oe Ca Soe 15
Pde UP ples 2h wot StS AN hs I 25
Seprodiiieng iho s ee liyees) aes. sere 5
pO ta tien Mette a ee Sects. 30
PISO Sa on oe rs Sao ak ae 57
pamineCheErys ) 2. Soot shee Ib
oy 0) 0 Ce Saag a EA ne Sl Me 4
murmetn cherry = 0): 2)5l ee ae 63
i a Bs 2 he ae Re Ce 19
Waa a. Ae hot ose eee 60

Ota serena Rees ee ee 4,610

In this area of 60 blocks of varying size, 712 dooryards, or estates,

averaged 6.5 host trees or shrubs.

In Hilo, island of Hawaii, host conditions are quite as favorable for
fruit-fly increase as in Honolulu.
trees and shrubs were found in certain yards during March, 1914.

YArp 1.
SSE ot2 2) aa ee
Surmnam cherry:....-....-.- Se ee
Hapemess DIMM... 202.2. 2.2-.2.--.--
Moumiaim apples. 2.262220 ..62- 222
ELS 210 00s Soe
USPS So: a i a
Common guava
Eragtlton banianha.-2.-----.-2...-..-

Thus the following numbers of host

Yarp 2—Continued.

Ree ene Ge ae nee: ee ea 2
SUPA WW OGELY: SULA VAs rics 2 ora cw Re HO 2
MOO ELCES stun atte he aaae 2 ati ke 14
Bananas.
BVM OS 2. sSek adsense 2
ESET! 1 Eee neg On RIES, Pe, Seek eae 1
RTGS Se Bee 2 oe [SNS Eee een et a 3
Mountain apple. 2.552 eeeetase ne 2
Ine Nba ects a ee wk, 5 2
Common) SUA a-ak ese eee ee 3
YARD 3.
dO Se | 04 0) (Lee ee ae eee a eek 11
jh eS er ee DR 2
sBheveila ecsa-se oe c tes eee eee ce a5 3
WAVOCRU Oran 4 tps sek ees PE a 1
| YARD 4
IR le Se he es 6 Sno Se 4
EST cae Oe, Spee rae Meee gt Sa 6
Tho Gale Sica 2 sat semcnt tea sections ak
Waneed Kamion <= 02) ete ols eo ken 3
Slits CReMyec aes see ee ce ee ee 2

Simawberry Puava. .... 2-2. -neaeu- 1

28 BULLETIN 640, U. S. DEPARTMENT OF AGRICULTURE.

The great variety of host vegetation which ripens its fruit at
different seasons leaves no time in Hawaii when fruits are entirely
out of season. The fact that certain hosts, such as the Chinese
orange, Surinam cherry, and mock orange, bear several crops a year
and others, such as specimens of the ball and the winged kamanis and
the bestill, appear to be seldom entirely free from ripening fruits,
assure food for the fruit fly the year round. The succession of fruits
also is increased by the individuality of trees of the same species, or
even of certain branches of a single tree, which results in a very
uneven ripening of the fruit. While the data in Table III do not
indicate the seasonal abundance of host fruits, they have been sum-
marized from the collections of clean-culture inspections during 1913
to show the remarkable succession of host fruits ripening in greater
or less abundance throughout the year in Honolulu. The presence of
so much ripening fruit, much of it on tall trees such as those illustrated
in figures 26, 27, and 28, has made it possible for the fruit fly to
multiply with unprecedented rapidity and thwart artificial remedial
measures.

Tasie IIl.—Data indicating the seasons of the year when inspectors of the clean-culture
campaign collected various fruits infested by the Mediterranean fruit fly.

| Be || Tear leyes 1S nN sianlia ~-[|a|s
teed eT a i ral st cli a oa) a STN st te Sy Sie ste
anes Piolo hele iS] S als [Sls la elf lala ees

didi g ide e)2)8 sl 8) 1S | 8 ISS Ss at oles

(E/E 2/212 \2 Gale l|2/2 |S B5 2/212 (ks
ANVOCAGOs-E 24 css eee eee Wea Solis Xe | esckl|eemilenee|) SO eees| ee salemesillsm acl =<m-[h 6 dl eee Sees eee
Calero) ae eeesese eee ae aee nll eel Seale > Sal I Slt S| Gl > ats WO Call 7S
Chinese orange. ...........-. YS MESS ee Sall eGo llinss (Weasel pecs iP Sall eG Gale oe o.G Ill oe ||
Chrysophyllum spp..--...-- Wal Sere a pes ail eel intl eee cl cme ets Rll are lees | orm eo re | S| ee
Coffees: saa. casks oes NW eSelfesel| 2S ZS ES NARGIS | SP OGM APSE SAIS | OS HESS [Poe
Damson plums! 22-2 ssseeee== Ni Wa Oa Ki Co Ta. asl > Sil Ga Salli IE Gal Ae elas pec isceel lies. los |) 2
Surinam cherry ......-..-.-- Ga Re [oN [pat fb Gen [Enea aS ll ea Gnd Pea le Sial ee leosSa|leceiinore: | os
gern a become cee See le lle | ce lees Gall esl Sa Gur || easel eesaeal lh DS oll Be-Sil asus [RPS Sel Neo eo eo
Grapeiniitess sess eee eee MEK | KOK YR OK Ne OK OK OR ROK IEE Ss a
GMAW aS: 22a occas a nets ial Sal sh eal eS) Ion OY [PGND Salli Galea Ge | >. Galle TD ce tS CITES lh
Kamani) pallsssseeesceceeeee eS lees ntl Ie Gall > Goal o> Gil |< (> He Ge GaN Gal | a Ga fa Ge hha Me
Kam Gulati = Seen en eee eee ees fee Gul lems llr oacall acl leee Call wenGe [|e ces ||oeete [obo |) 1-4 | Semel eel nev eyloee <ler et
AMO Sse a5 5 ee 8 sees eee iG hare Gal Ie eon a>] >i a I | I Gall a MNOS. Ih Ps lar
Teequntss ses se 209 4 eee | Xe KP GP EET ST SR | STO TS | ko Se eat aaa
Mane owen seers aca sel DK DR lh DR MPD D1! ORF Cao TES EE 1 alee ee
Mockioramgerss. a2 eee > allie? Vin il Uin> <u ft” Le Ga He, Ga Gael Gal > Ge GI Gall I SS NIL <2 |)
Mountain pler= ec pcnaceees|oeee Bee ?ce | eh hou Fae eel fee Goal BP - Gal rrel ie Gu Ieee ei mieaiabrc PS. |S
Orangeare tose tenes eee Peal besser Gall erase eee Vayu fe Sa ea [econ Self Poel l ee COI ING oCallesc [loc
IPED AV dea ra ae fee eae YN ae, linea bee sae | PG (Geel laa GI Gel Cal > allie Gals Cali ee 1) S:
ROACH cece nce Suse cee lee Mellie 2eall Pi eG NEON A OO TOR a DS NK Nee 1G 1 ei ca ee
ROPPEL e232 s2se nee Spee KX OX lesen OR | OT OR OK AY Oe |r
Pricklymeateoasse ee eae [eve Sialllos 52] OX ls tei] sss cell PE ce cle eee S ee tera een es cll | tas ca
Roseiappless--e-osse ee aes levee] XW [eo] XP XIX | KX |X| MK KI KX a= ee
SUCTER YO) NO sccoyecccsece secre |Sb8el pase eee Oper Seed eed peacioocelo x CIP ee WO Hoes oe o---|
BOS aaa ae esa eee EOC AOS Dal ae, Gaal PSone Se NG GV Jin Sel pee Nf |< || Se
Sout sopict™i sa eeee ee Jeane] niescleime | AMEE TOK, | IOGE | Kile ceed: aati aKa lex a cele
Maridaritiac meres cco sees NPS ele Gal P Sa PG eu lee | Vines Nl 2G [Gal SUG eaaal eS NPCS |! os
IU oosaescascessneo ses - Nigra eal Foe Wiesel Dac | eal eel eGullet eal lees pO ESSSI Oe | Oe |/ Ss) Oc:
Kamani, winged. ....-.--2--| X |X | KK ER Oe KB Ke I 1) cae
Spanishichertye ss. see esesee cee DR Gnas e ae] eretetal farcoers [reise | meme rar= al rete onl| ee | ce oe
Bartlettpeatsaesso- o> ae ares aoe [eeedlles= easel rele sia eeel|sccellasegecee|zced|| 2X || OS | OX Ic

1 This table is not intended to indicate the seasonal abundance of host fruits.

29

THE MEDITERRANEAN FRUIT FLY.

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30 BULLETIN 640, U. S. DEPARTMENT OF AGRICULTURE.
HOST CONDITIONS IN THE COUNTRY.

While host conditions within the city limits render useless such
artificial control measures as can be applied under existing condi-
tions, country host conditions are almost, if not quite, as discour-
aging. Here the fruit fly has been able to establish itself, often
miles from towns, in some one or more of its hosts which have es-
caped cultivation and have spread over uncultivated and uncultiva-
ble areas. Of such hosts, the common guava is the most abundant.
It has taken possession of the roadsides, pastures (as shown in fig.
26), vacant town lots, mountain gulches and hillsides, and even
crevices on precipices. So easily does the plant grow from seed and
so thoroughly distributed are its seeds by cattle, birds, and man,

Fig. 26.—Men cutting down a dense thicket of guava bushes. In such a guava scrub ripening fruits are
present throughout the entire year and in them the Mediterranean fruit fly breeds, often far from culti-
vated fields. (Authors’ illustration.)

that it is seldom that in the lowlands, except in very arid areas, a
bush can not be found within a stone’s throw. In pastures and moun-
tain gulches up to an elevation of at least 1,500 feet, particularly
where sheltered from strong winds and well watered, the guavas may
become very treelike and form dense thickets. While the guava
fruits most heavily during the spring and fall months, the bushes
are continuously in bloom and ripen a sufficient number of fruits to
support the fruit fly every month in the year.

Second to the guava as a host occurring in the wild uncultivated
areas is the prickly-pear cactus. Though the fruits of this plant are
not preferred by the fruit fly, they are sufficiently infested in the
absence of more favored hosts to serve as food, and, as in the case of
the guava, there is almost no time during the year when a few ripe
fruits can not be found in any cactus scrub.

THE MEDITERRANEAN FRUIT FLY. 31

Other host fruits, wild or escaped, are not so generally distributed.
As a few of the many examples, there may be mentioned a grove of
ball kamani trees in an isolated valley on the Island of Molokai,
gulches overgrown with the passion vine and the damson plum on
the island of Maui, the thickets of winged kamani growing along the
windward shores of the island of Oahu, and the wild coffee in the
forests of Oahu and Hawaii.

In addition to the wild fruits in country places, the fruit fly finds
strongholds in the many, and often isolated, native home sites scat-
tered throughout the coastal region. About these may be growing
the mango, rose apple, orange, peach, ball and winged kamanis, etc.
The Kona district of Hawaii has large areas containing thousands of
acres of coffee under cultivation in which the fruit fly finds food at
all seasons of the year, because of the uneven ripening of the crops
due to the varying altitudes at which coffee is grown.

CLEAN CULTURE A FAILURE IN HAWAII.

Clean culture in its broadest sense includes not only the detection,
collection, and destruction of all infested fruits, but also the elimi-
nation of useless or unnecessary host vegetation. In some one or all
of its phases it has been recommended and practiced in every coun-
try where the fruit fly is a pest, but in nearly all of these the apparent
indifference displayed by the majority of the people, no matter how
much they may have lamented their losses, has rendered clean culture
inefficient.

Theclean-culture campaign instituted by the Hawaiian board of agri-
culture during the fall of 1911 and continued by the Federal Bureau
of Entomology from October, 1912, until April, 1914, was a failure from
the very start in that it did not protect fruits from attack. There were
minor contributory causes, but the main reason for failure was the
insurmountable difficulties placed in the way of success by territorial
legislation, adverse host and climatic conditions, and the lack of any
commercially grown crop worth protecting. This method of control
proved hopeless after the first few months’ trial from the stand-
point of alleviating the Hawaiian situation, and while the destruction
of fruit was encouraged, in the absence of a better plan for lessening
the opportunities for spread of the pest to the coast by means of
infested fruits carried on board ships sailing from Honolulu, it has
since been discontinued.

It is doubtful if any clean-culture campaign against the fruit fly
has ever been organized so efficiently or on so large a scale as was
that organized by the Hawaiian board to include Honolulu. That
this method should prove a failure under Hawaiian conditions is no
reflection upon the ability of those directly in charge of the work.
The law prohibited inspectors from gathering and destroying the

82 BULLETIN 640, U. S. DEPARTMENT OF AGRICULTURE.

fruits unless they could first prove to the satisfaction of the property
holders that each fruit was infested. This restriction placed upon
the activity of the inspectors led to numerous difficulties between
inspectors and those opposed to clean culture. This law also pro-
hibited a systematic gathering of all host fruits within a given area,
thus necessitating Many examinations for the removal, as they
ripened, of the fruits of each single tree. As fruits ripen rapidly in
the semitropics, it proved a physical impossibility to arrange visits
of inspectors frequently enough to prevent infested fruits from falling
to the ground.

The data of Tables II and III demonstrate the immense number
and diversity of host trees and shrubs in Honolulu and the ease with

Fic. 27.—Ball kamani trees grown for shade and ornament. This tree grows to a large size, and some-
times in dense thickets in the forest. Its fruits ripen at all seasons of the year and are badly infested by
the Mediterranean fruit fly. (Authors’ illustration.)

which the fruit fly, uncurbed by climatic conditions, finds fruit for
egg laying during any day of the year. It is absurd to endeavor to
remove all the fruit from many of the huge trees of the islands. There
are numerous large trees (figs. 27, 28) beneath which infested fruits
may be gathered each week in the year, yet the trees are so tall and
brittle that no inspector can remove the fruits before they ripen.
One yard in Hilo has 15 host trees from 20 to 50 feet high. To these
examples might be added many others in which the removal of fruits
is equally impracticable. Often the fruits of the star apple, for
mstance, ripening in the tops of tall trees do not fall until long after
they have shriveled up and until after the many larve developing
within have matured and dropped from them to the ground. One

THE MEDITERRANEAN FRUIT FLY. 33

acre of guava or of coffee can support the fly throughout the year
without the aid of other host fruits and form a center for the
reinfestation of surrounding areas. Notwithstanding the fact that
the bulk of the ripening and infested fruits can be collected except
during the mango season, lasting from May to July, and fruit-fly
conditions unquestionably improved from the standpoint of the
numerical abundance of adult flies, the important fact remains that
the number of fruit flies that succeed in reaching maturity is suf-
ficiently large to infest practically every fruit ripening within the city.

Clean culture can not be made effective under present conditions.
The islands are thoroughly overrun with the fruit fly, and this applies

Fic. 28.—The fruits of this tree, the winged kamani, ripening throughout the year, are badly infested by
the Mediterranean fruit fly. The nuts of this one tree are enough to supply adult flies for an entire
neighborhood. (Authors’ illustration.)

quite as much to the guava scrubs in pastures or lava flows and in
mountain gulches as within city limits. By far the larger proportion
of the host trees and shrubs are grown more for protectionfrom the
tropic sun and for their ornamental value than for their fruits. Large
numbers of the host fruits are not edible. The destruction of host
vegetation is out of the question until it can be proved that some
worth-while advantage can be gained. To cut down all host trees in
Honolulu at present would mean the removal of a large percentage
of her prized vegetation without giving her citizens any adequate
compensation.

34 BULLETIN 640, U. S. DEPARTMENT OF AGRICULTURE.
VALUE OF ELIMINATING HOST VEGETATION.

In Honolulu many mango and orange trees were either cut down
or severely trimmed, ‘but those cut formed too small a percentage of
the entire host vegetation to serve a practical purpose. The only
places where the elimination of host vegetation yielded favorable
results were about banana and pineapple plantations where the work
was done in accordance with the regulations of the Federal Horti-
cultural Board. In these instances the destruction of vegetation did
not eliminate the adult flies, for these came in from surrounding
areas. It did, however, lessen the danger of immature stages becoming
attached to the packing material of bananas and pineapples shipped
to the mainland.

Should the Mediterranean fruit fly ever become established in
California or the Southern States, however, where there is no such
wealth of native host fruits and where climatic conditions will prove
an important factor in control, the elimination of host vegetation
will play a most valuable part in remedial measures. In Algeria the
infestation of oranges greatly increased after such crops as peaches
and persimmons were grown. These fruits furnished food for the
fly during the summer and early fall months, which were for the fly
starvation months previous to the cultivation of these crops. Aided
by these summer crops, the fruit fly was able to increase greatly,
so that when the orange crop began to ripen during the fall and winter
months the pest could attack it with increased force. In Bermuda
the elimination of a comparatively few host trees, numerically speak-
ing, would mean the elimination of breeding places for considerable
areas. The destruction of unnecessary and valueless host trees will
not only restrict the breeding ground, but will often so break up the
sequence of ripening hosts that many adult flies will die while
attempting to bridge the starvation periods when no fruits can be
found for egg laying.

DESTRUCTION OF INFESTED FRUITS AND SPRAYING.

The destruction of infested fruits and spraying are remedial meas-
ures that should go hand in hand. In Honolulu they have not given
satisfactory results for reasons beyond the control of man, as set
forth on pages 24 to 33. Nevertheless, they can be made successful
in commercial orchards, if applied with intelligence and persistence
throughout a neighborhood. One indifferent neighbor can spoil the
work carried on in surrounding orchards. A community of growers
must determine in what crop their interests are centered and im-
partially eliminate nonessential fruits. Then, and, as a rule, not
until then, will labor spent on the destruction of infested fruits and

THE MEDITERRANEAN FRUIT FLY. 35

on spraying prove worth while. Sprays are applied to kill the adults;
fruits are destroyed to kill the eggs and contained larve.

DESTRUCTION OF INFESTED FRUITS.

Larve infesting fruits may be killed by submerging the fruits in
water or by burying, boiling, or burning the fruits. The choice of
method will depend largely upon the quantity of fruit to be handled
and upon local conditions. The surest way to kill all immature
stages of the fruit fly is to boil or burn the fruits. Burning the fruits
is often expensive and, when trash in compost holes is depended upon
to furnish the fuel, the burning operation is likely to be unsatisfactory;
for in Honolulu, at least, the amount of fruit to burn is so greatly in
excess of the trash that the work is incompletely done. Bringing
infested fruits to the boiling point will kill all forms of the fruit fly.
Submerging fruits in ordinary cold water for five days will either kill
all larve and eggs or prevent their further development.

Burial in soil is a satisfactory method, provided the fruit is buried
deep enough and afterwards cracks are prevented from developing in
the earth above the fruits as the latter decay and settle. It should
be remembered that just after transforming from the pupa the
adults are so soft that they have the remarkable ability to force their
way through incredibly small openings. Hence, a crack in the soil
extending down to the fruit, even though it be no wider than the
thickness of ordinary blotting paper, is wide enough to permit the
adults to reach the surface and so thwart the purpose of fruit burial.
Adults can not make their way through 1 foot of well-tamped soil,
but because burial or burning is left to subordinates, who may
slight the work, boiling or submergence of fruit in water is more

highly recommended.
SPRAYING.

As adult flies can not lay eggs until 4 to 10 days after they emerge
from the pupa, anything that will kill them during this period is
useful. Such a remedy has been found in poisoned-bait sprays.
These are composed of a sweet substance attractive to the flies,
a poison, and water, Mally, who first used a poisoned spray in control-
ling this pest, used a formula containing: Sugar, 3 pounds; arsenate of
lead, 4 ounces; water, 5 gallons. This he applied at the rate of 1 to
14 pints to each 10-year-old peach or nectarine tree. Lounsbury
used 6 pounds of brown sugar, 6 ounces of arsenate of lead paste,
and 8 gallons of water. Severin used the Mally formula but increased
the poison to 5 ounces. Weinland used 34 ounces of arsenate of
lead, 10 pounds of brown sugar, 5 gallons of plantation molasses,
and 50 gallons of water. All of these formulas have proved to be
efficacious.

36 BULLETIN 640, U. S. DEPARTMENT OF AGRICULTURE.

Attempts to control the Mediterranean fruit fly under Honolulu
conditions were unsuccessful. The number of adults killed was
great, yet a sufficient number survived to infest all fruits that ripened.
From what is known, however, of the benefits derived from these
sprays in other countries, there is no question but that poisoned-bait
sprays, when intelligently applied under such commercial conditions
as exist in California and Florida, will prove successful. Thus Mally
in South Africa states that a ‘‘severe outbreak of the pest in a commer-
cial peach orchard was brought to a sudden and practically complete
halt, and the fruit maturing later was marked under the guarantee of
freedom from maggots,” while the infestation among fruits on check
trees increased until all fruits became infested. Newman in Western
Australia estimates the cost of spraying an acre when one applica-
tion of one pint of spray per tree is made every 12 to 14 days to
be from $1.50 to $2 per fortnight, and states that this sum is a mere
bagatelle to the loss of fruit during a similar period over a like area.
Both Mally and Newman, working under conditions of less rainfall
than obtained at Honolulu, and more like those of California and of
fall and winter in Florida, believe that good results will follow the
consistent application of poisoned bait sprays, particularly when
supplemented by the proper destruction of infested fruits.

Honeybees are not endangered by the application of pcisoned-
bait sprays.

COLD-STORAGE TEMPERATURES.

Cold-storage temperatures do not lessen the damage already done
fruits by larve within them, but they may become of inestimable
value in guarding fruits against further attacks while in storage or
transit and in freeing them from suspicion as carriers of the fruit fly.

For the details of the effect of cold-storage temperatures upon
eggs, larve, and pupx of the Mediterranean fruit fly, application
should be made to the Bureau of Entomology for articles already
published. Fruits of almost any variety commonly held in storage
are held at temperatures varying from 32° to 45° F., with preference
shown to a range of 32° to 36° F. It may be said that no immature
stages of the Mediterranean fruit fly can survive refrigeration for
seven weeks at 40° to 45° F., for three weeks at 33° to 40° F., or for
two weeks at 32° to 33° F.

It seems reasonable to conclude that sooner or later the certifica-
tion of properly refrigerated fruit will be practicable. When an
association of fruit growers, or a people, find it financially worth
while, there is no reason why they can not operate a central refrigera-
tion plant under the supervision of an official whose reputation shall
be sufficient to guarantee all fruits sent out from the plant to be
absolutely free from danger as carriers of the fruit fly.

—_

THE MEDITERRANEAN FRUIT FLY. 37
PROTECTIVE COVERINGS.

The only certain method now known of protecting fruit from fruit-
fly attack in Hawaii is to cover them, when still very green, with some
type of covering through which the fly can not lay her eggs. In many
places ordinary cheesecloth sewed into bags, large enough to be slipped
over the tree and tied about the trunk, have been used. These have
been tried in Honolulu, but difficulty was experienced in putting the
bags on soon enough and in making certain that no adult female flies
were inclosed during the process.
Considering the cost of material
and the real danger of inclosing
flies, the impossibility of covering
many trees, and the breakage due
to winds, this method of protection
is not recommended.

The protection of the fruit on
individual branches with cover-
ings of cloth or paper is entirely
feasible and very popular in Ha-
wail. Individual fruits inclosed
in ordinary paper bags (fig. 29) are
well and cheaply protected. Cov-
erings of cheesecloth for separate
fruits are not as good as paper, for
the fruit fly can lay her eggs
through certain coarser-woven
kinds after the cloth has become
matted against the fruit by rains.

Orange and small mango trees
with their fruits inclosed in paper
bags are often seen in Honolulu.
Though this method of covering

Fig. 29.—Quince fruit protected from fruit-fly
attack by a paper bag. The bag is slipped over

each fruit gives protection, it in- the fruit while it is still quite green. Although

c Z this method of protection is not practical on a

volves much labor and patience, large scale, it is used much in Hawaii for the

and its practicability can be de- protection of dooryard or experimental fruits.
(Original. )

termined only by the value placed
upon the fruit by the owner. So severe, however, is fruit-fly attack
in Hawaii that this method, or some one of its many modified forms,
rust be used if fruits are to be brought to maturity uninfested.

NATURAL CONTROL OF THE FRUIT FLY.

No striking examples of control by natural agencies were evident
in Hawaii previous to the introduction of parasites. Larvze are killed
in large numbers within fruits which are permitted to remain on the

38 BULLETIN 640, U. S. DEPARTMENT OF AGRICULTURE.

ground exposed to the direct sunlight in summer, but many larvee
escape even from such fruits. An examination of 17 mangoes
exposed over sand on shallow trays to the sun for two days in August
revealed 17 living and 98 dead well-grown larve in the fruit, and 103
that succeeded in safely leaving the fruit to form pupz in the sand
beneath. The small brown ant,! so common about the lowlands of
Hawaii, unquestionably is a factor in natural control. It is fre-
quently found swarming over and in fallen fruits and kills many
larve as they leave the fruits to pupate. Ants were observed to
remove from a fallen ball kamani nut 86 medium-sized larve during
a 40-minute period, but they failed to reach 34 other larve in a firmer
portion of the fruit.

No natural checks upon fruit-fly increase in Hawaii, aside from
introduced parasites, are of practical value; but in many other lands
climatic checks are unquestionably of great value, and, as in many
places in Spain, for instance, are the only checks that make fruit
production possible without the use of remedial measures.

CLIMATIC CHECKS.

Observations made in various countries indicate that the Mediter-
ranean fruit fly will not be a serious pest when the monthly mean
temperature falls to or below 50° F. for from three to four consecutive
months during the year. In Hawaii the climate is not cold enough
throughout the fruit-growing regions to act as a serious check on
fruit-fly increase. Development progresses most rapidly after the
Hawaiian means reach 75° to 79° F. At a mean of 68° F. develop-
ment requires about twice the time. A temperature of 58° to 62° F.
may increase the period of development to three to four times the
normal period for the warmest weather. Larval development in
apples stored outdoors at temperatures ranging from 31° to 64°
F. (mean, about 51° F.) was slow and was attended by no un-
usual mortality. No development occurred at 26° to 70° F.
(mean, 48° F.), and nearly all larve were dead at the end
of six weeks. Very few fruit flies can develop at 49° to 50° F.,
and none at temperatures below this point. Complete mortality
will follow continued exposure to temperatures below 50°F. An
exposure for two to three weeks at 32° F. will kill all stages of the
fruit fly, but an exposure to this low temperature for four days has
practically no effect upon the fly. Sixty-two of 248 larvee survived
an exposure for five days to 21° to 28° F. These facts indicate that
the Mediterranean fruit fly is a very hardy and persistent enemy in
spite of the quickness with which it responds to checks upon its
development resulting from the low temperatures ordinarily experi-
enced in semitropical countries.

1 Pheidole megacephala Fab.

THE MEDITERRANEAN FRUIT FLY. 39
PARASITES.

The very climatic and host conditions that have made the Medi-
terranean fruit fly an unusually serious pest in Hawaii and that,
with crop conditions as they are, have made artificial methods of
control impracticable, have been most favorable for an attempt
at control by means of parasites. An abundance of the fruit fly upon
which to feed and a climate permitting increase each month in the
year have made conditions ideal. The search for and discovery of
parasites, and their introduction and establishment where previously
there had been none, has been one of the entomological romances of
the present time. The
parasites now at work
killing the fruit fly in
Hawaii have been in-
troduced by the Ha-
waiian Board of Agri-
culture and Forestry as
aresult of the Silvestri
and the Fullaway-
Bridwell expeditions
to Africa.

These two expedi-
tions resulted in the
establishment in the
islands between May,
1913, and October,
1914, of four promis-
ing parasites: one from
South Africa,' one
from eastern Austra-
lia? and two from

5 > i Fig. 30.—Diagrammatic drawing ofa cross section of a coffee cherry
Nigeria,’ West Africa. to illustrate comparative ease with which the South African para-

site can lay eggs in the fruit-fly larva: a, Coffee bean; b, pulp
Of these, only ene the destroyed by maggot; c, skin of cherry; d, maggot of fruit fly; e,
South African Opius, parasite forcing its stinger through skin of cherry into maggot.

was discovered as a = (Omeinsl)

parasite of the Mediterranean fruit fly. The three others were found
parasitizing other fruit flies, and they have adapted themselves
in Hawaii to the Mediterranean fruit fly. None of them, however,
has been known to attack the melon fly in the gardens in
Hawaii. Large numbers of all the parasites have been reared and
have been liberated in all parts of the islands, until to-day they are
well able to care for themselves. They have multiplied with
remarkable rapidity and have unquestionably reduced the numerical

1 Opius humilis Silv. 2 Diachasma tryoniCam. * D.fullawayi Silv. and Tetrastichus giffardianus Silv.

40 BULLETIN 640, U. S. DEPARTMENT OF AGRICULTURE,

abundance of the fruit fly. To-day no batch of infested fruit can be
collected from which fruit-fly parasites can not be reared.

Only a beginning has been made in determining the effectiveness
of parasites as a control factor against the fruit fly in Hawaii. The
rapidity of establishment and the increase of the parasites have been
very gratifying, yet the data already published recording the per-
centages of parasitism during the years 1914, 1915, and 1916 indicate
that while parasitism in thin-meated fruits, such as coffee (see (fig. 30),
may be consistently very high, in thicker fruits, like the orange, it is
consistently very low. Thus the parasitism among larve developing in
coffee may range between 90 and 100 per cent, while that among larve
of the Chinese orange is more likely to range from almost nothing
to 30 per cent. High parasitism among larve in such fruits as coffee
is due to the fact that the larve are within reach of the parasite.
On the other hand, the larve within such fruits as the orange may
feed about the seeds and therefore remain safe from attack so long
as they stay at the core, and are subject to attacks only when they
come to the surface of the fruit.

Since adult fruit flies can live many months and lay eggs quite
regularly, they have been able, with the aid of the unprecedented vari-
ety and abundance of host fruits in Hawaii, thus far to keep such an
ascendancy over their parasites that they cause the infestation of
practically all fruits ripening. It would appear that unless effective
pupal and egg parasites are introduced, or more care is given to the
elimination of host fruits which more thoroughly protect the larvee
from parasite attack, or to the planting of fruits which make possible
the reproduction of large numbers of parasites, little practical value
will result from the work of the parasites from the standpoint of ren-
dering host fruits free from attack.

Though it seems evident that the favored host fruits will always be
well infested if present cultural conditions continue, it is hoped
that the efficiency of the parasites may be sufficiently enhanced
to free from attack such fruits as the avocado and the better varieties
of mangoes. In Kona, Hawaii, where the percentage of parasitism
in coffee cherries (see fig. 30) has been phenomenally high for three
years, it has not been high enough to free more than an occasional
cherry from attack. The control exerted by parasites has, however,
effected a benefit to coffee growers which probably already has repaid
the Territory of Hawaii for all money expended in the introduction
of parasites.

The general effectiveness of control by parasites can be increased
best by the discovery and introduction of a good egg parasite.

THE MEDITERRANEAN FRUIT FLY. 41

QUARANTINE MEASURES TO PREVENT INTRODUCTION.

To prevent the Mediterranean fruit fly from becoming established
in the mainland of the United States, the Federal Horticultural Board
has promulgated Quarantine No. 13, which provides that its agents,

Fic. 31.—Chinese laborers inspecting bananas. Each bunch of bananas exported from Hawaii to Cali-
fornia is inspected for bruised, cracked, or suspicious looking fruits. (Original.)

both in Hawaui and at the mainland ports of entry, shall have strict
supervision over the movements of all fruits permitted entry to the
mainland from Hawaii. Quarantine No. 13 makes it unlawful for a

Fig. 32.—Inspecting bananas as they are unloaded on the docks at San Francisco: Inspector making cer-
tain that each bunch bears an inspection tag and has been wrapped in material permitted by law.
(Photo by Maskew.)

person to ship or carry any fruit from the Hawaiian Islands except
ordinary eating bananas, pineapples, taro, and coconuts, and these
will not be passed by inspectors at ports of entry, such as San Fran-
cisco, Los Angeles, or Seattle, unless they have been inspected by the

49 BULLETIN 640, U. S. DEPARTMENT OF AGRICULTURE.

Federal agents in Hawaii and bear a Federal certificate of inspection.
(Fig. 31.)

In Hawaii every precaution is taken to have bananas and pine-
apples grown under conditions that will prevent spread of the fruit
fly. Plantations, packing sheds, and packing materials are inspected
sufficiently often to insure their being in keeping with the regulations
of the Federal Board. No fruit can be lawfully accepted for trans-
portation to the mainland by any transporting company in Hawaii
until it has been inspected and passed and permits for its acceptance
have been issued to the transporting company by agents of the Board.
Furthermore, no fruit can be lawfully removed from ships at ports
of entry at the mainland unless the permit issued the transporting
company in Hawaii is found attached to the bill of lading by the

Fiq. 33.—Pineapples never breed fruit flies in Hawaii. To be doubly certain that the packing material
contains no fruit-fly pups, all crates of pineapples unloaded on the docks at San Francisco are fumigated
with gas after tarpaulins have been thrown over the crates to prevent the gas from escaping. (Photo
by Maskew.)

Federal agent, and unless each package or crate of fruit bears the

inspection tag above referred to. (Figs. 32 and 33.)

Passengers and ships are permitted to take on board in Hawai
fruits of all descriptions for consumption while en route to the coast.
All contraband fruits, however, must be eaten or destroyed before
the ship comes within the 3-mile limit of the mainland. Otherwise
the transporting company, or the individual passenger, whichever is
the offender, is subject to fine or imprisonment, or both.

SUMMARY.

The Mediterranean fruit fly has become so thoroughly entrenched
in Hawaii as a result of favorable climatic and host conditions that
artificial remedial measures for its control are not practicable. Intro-
duced parasites have multiplied wonderfully well and already have
proved of practical value in safeguarding the coffee crop from losses
due to fruit-fly attack. Though it is certain that the parasites can

THE MEDITERRANEAN FRUIT FLY. 43

never exterminate the fruit fly or cause the raising of the quarantine
against Hawaiian fruits, much ultimate good is expected of them. It
is hoped that by lessening the abundance of the fruit fly many fruits
that now become badly infested before they are ripe enough to eat
may be able to mature uninfested to a point where they will be useful
to man. At present almost all edible fruits in Hawaii, and many
ornamentals, making a total of 72 kinds of fruit, are subject to attack.

Judging from the past history of the Mediterranean fruit fly, only
the vigilance of quarantine officials and the hearty cooperation of
travelers will prevent its establishment in California and the Gulf
States. Every barrier possible has been erected by State and Federal
quarantines, so that there is now little danger of the pest gaining
entry through the medium of commercial shipments of fresh fruits.
But quarantine officials have found the pest in fruit concealed by
tourists and in mail and express packages sent from infested countries
by uninformed persons, and it is by such avenues that the pest is most
likely to be introduced. These avenues, also, are the most difficult
of detection, and their closing is dependent mainly upon educa-
tional campaigns to convince the public of the necessity of quaran-
tine measures, and upon the unselfishness and personal honesty of
travelers. At present only bananas, pineapples, taro, coconuts, and
certain other vegetable products not subject to attack, are permitted
entry from Hawaii, and these only after the regulations of the

Federal Horticultural Board have been fulfilled.

PUBLICATICATIONS OF THE U. S. DEPARTMENT OF AGRICULTURE
RELATING TO INSECTS INJURIOUS TO CITRUS AND OTHER SUB-
TROPICAL FRUITS.

AVAILABLE FOR FREE DISTRIBUTION BY THE DEPARTMENT.

Control of the Citrus Thrips in California and Arizona. (Farmers’ Bulletin 674.)

Carbon Disulphid as an Insecticide. (Farmers’ Bulletin 799.)

Common Mealybug and its Control in California. (Farmers’ Bulletin 862.

Fumigation of Ornamental Greenhouse Plants with Hydrocyanic-acid Gas. (Farm-
ers’ Bulletin 880.)

Fumigation of Citrus Trees. (Farmers’ Bulletin 923.)

Control of the Argentine Ant in Orange Groves. (Farmers’ Bulletin 928.)

Spraying for the Control of Insects and Mites Attacking Citrus Trees in Florida.
(Farmers’ Bulletin 933.)

Citrus Fruit Insects in Mediterranean Countries. (Department Bulletin 134.)

The Mediterranean Fruit Fly in Bermuda. (Department Bulletin 161.)

Katydids Injurious to Oranges in California. (Department Bulletin 256.)

Argentine Ant: Distribution and Control in the United States. (Department
Bulletin 377.)

The Melon Fly in Hawaii. (Department Bulletin 491.)

Fumigation of Ornamental Greenhouse Plants with Hydrocyanic-acid Gas. (Depart-
ment Bulletin 513.)

The Mediterranean Fruit Fly in Hawaii. (Department Bulletin 536.)

The Citrus Thrips. (Department Bulletin 616.)

The Mellon Fly. (Department Bulletin 643.)

Some Reasons for Spraying to Control Insect and Mite Enemies of Citrus Trees in
Florida. (Department Bulletin 645.)

The Argentine Ant in Relation to Citrus Orchards. (Department Bulletin 647.)

Preparations for Winter Fumigation for Citrus White Fly. (Entomology Circular 111.)

Spraying for White Flies in Florida. (Entomology Circular 168.)

FOR SALE BY THE SUPERINTENDENT OF DOCUMENTS, GOVERNMENT PRINTING
OFFICE, WASHINGTON, D. C.

Mango Weevil. (Entomology Circular 141.) 1911. Price, 5 cents.

Fumigation for Citrus White Fly, as Adapted to Florida Conditions. (Entomology
Bulletin 76.) 1908. Price, 15 cents.

Fumigation ‘Investigations in California. (Entomology Bulletin 79.) 1909. Price,
15 cents.

Hydrocyanic-acid Gas Fumigation in California. (Entomology Bulletin 90, 3 pts.)
1913. Price, 20 cents.

Fumigation of Citrus Trees. (Entomology Bulletin 90, pt. 1.) 1913. Price, 20 cents.

Value of Sodium.Cyanid for Fumigation Purposes. (Entomology Bulletin 90, pt.
Il.) 1913. Price, 5 cents.

Chemistry of Fumigation with Hydrocyanic-acid Gas. (Entomology Bulletin 90,
pi. III.) 1913. - Price, : cents:

White Flies Injurious to Citrus in Florida. (Entomology Bulletin 92.) 1911. Price,
25 cents.

Orange Thrips, Report of Progress. (Entomology Bulletin 99, pt. I.) 1911. Price,
5 cents.

Red-banded Thrips. (Entomology Bulletin 99, pt. II.) 1912. Price, 5 cents.

Natural Control of White Fliesin Florida. (Entomology Bulletin 102.) 1912. Price,
20 cents.

44

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