A.^

•*

baaed August ;, 1914.

U. S. DEPARTMENT OF AGRICULTURE,

BUREAU OF ENTOMOLOGY.
L.O. HOWARD, Entomologist and Chief op Bureau.

I .

THE PINK BOLL WORM.

Hv W. 1). Httnter,
In Charge 0/ Southern Field Crop Insect Investigations, Bureau 0/ Entomology .

INTRODUCTION.

Considerable attention has recently been attracted to the pink boll-
worm (GelecMa gossypiella Saund.) (fig. 1 ) on account of the possibility
of its introduction into the United States. This statement has been
prepared to make available such general information as has been
called for from time to time by planters and manufacturers.

As is well known, many of the most injurious insect pests of the
United States have been imported from foreign countries. There
seems no doubt that
the |>ink bollworm
would be able likewise
to establish itself if it
were introduced. It
would be very likely
to add greatly to
the damage sustained
by the cotton crop
of this country from

insects, which now amounts to about fifty millions of dollars per
annum. That the introduction of the insect is easily possible is due
to certain features of its life history which will be described later. As
a matter of fact, in 1912 a shipment of 500 pounds of Egyptian cotton
Beed which was heavily infested by the pink bollworm reached
Arizona. On account of the effective control law in that State and
the watchfulness of Dr. A. W. Morrill, the State entomologist, the
whole shipment was destroyed by fire. Otherwise it is extremely
probable that a new and very destructive cotton insect would have
been introduced. This would have been particularly unfortunate

Note.— This circular gives information about an insect that damages cotton crops and whose impor-
tation into this country is to be guarded against. It is of especial interest to both cotton growers and
manulacturers.

51617'— 14

Fig. 1.— Pink bollworm (Gelechla gossypiella): Full-grown larva,
lateral view. Much enlarged. (Original.)

THE I'INK BOLLWOBM.

in Arizona, on account of the comparative freedom of the cotton
grown there from insect injury and the definite indication that the
Stat.' will soon be able to produce large quantities of cotton of em
rior quality which can not be grown in other parts of the count]

O n j^y i, 1913, the Federal Horticultural Board promulgated
quarantine against cotton seed from all foreign countries, with
object of preventing the invasion of the ;>ink bollworm. Since this
quarantine has been in effeel several shipments of cotton seed 1
been intercepted. All wen- found t<> be infested by the pink boll-
worm; one shipment, which was to he forwarded to Arizona, Bhowed
an infestation of 20 per cent.

In this connection it may be stated that there ifi no longer any need
for importing cotton seed from Egypt, since there is an amplesupplyof

well-selected and
cfimatized seed a\ ail-
c T able in Arizona.

DISTRIBUTION.

The pink bollworm
was described oti

nally from India in
1st;!. Since that time
it has been found more
or less generally wide-
spread in India, I

of Egyptian cotton showing typical Injuries made by the j (m g nrmftj Straits
ink bollworm. Much enlarged. (Origin '

ttlementf . pt,

British East Africa. German East Africa, Nigeria, Sierra Leone, and
the Hawaiian Ishuuls. In the Hawaiian Inlands it was undoubtedly
introduced in cotton seed from India. There is also a doubtful
record of the occurrence of the species in Japan.

The question has been raised as to whether the pink bollworm is
not already established in the United States. Vm- several reasons it

seems certain that this is not the case. Since the boll weevil invaded
the country planters have paid very especial attention to the in-
found on the cotton plant. Each year hundreds of specimens mis-
taken for the boll weevil are sent to the Department of Apiculture
and to State entomologists. Since the pink bollworm might easily
be mistaken for the boll weevil by planters it is altogether likely that
it would have been bmnd if it were established at any point in the

United States. Moreover, the chances of introduction have been

small until recently, because the Egyptian crop has not been generally

infested until within the. Last few years.

Fig. 2.

TIIK I'INK IIOI.I.WOKM.

HOW THE INSECT SPREADS.

The moth which is the parent of the pink bollworm is a fragile
insect and, can fly no great distance. II' the spread of the species
depended upon the flight of the adult its dispersion into new regions
would he very slow. However, the fact that the immature stages occur
in cotton seed, furnishes a ready means of artificial spread over great
distances. (Sec fig. 2.) In Egypt experiments have shown that the
larvae may live within the cotton seed for as long as seven months.
Tins would allow the insect to he transported to the most remote
quarters of the earth. It is altogether likely that the original home
of the species was in Asia and that various parts of Africa have
become infested by ship-
ments of seed from that
country, as was the ease in
the Hawaiian Islands.

OCCURRENCE OF INFESTED
SEED IN BALED COTTON.

\ '~~s" ^\

\^~<&?y%y /

Fig. 3.— The cotton belt of the United States, from which
all shipments of Egyptian cotton seed are excluded by
quarantine. (Original.)

During the course of the
investigation of the possible
introduction of the pink
bollworm into the United
States it was found that a
considerable number of
seeds are to be found in the
bales of Egyptian cotton. It appears that a certain number of seeds
pass around the ends of the rollers in the gins, and some may pass
between the roller and the knife through small openings due to wear.
When the possibility of the introduction of the pink bollworm, in
seeds in bales of lint, came to attention an investigation was made in
certain mills in New England and the South where Egyptian cotton is
used. The picker waste from37baleswasohtained and examined care-
fully. The number of seed recovered varied from 27 to 600 per bale, the
average per bale being 215. It was noticed that the number of seed
found in the picker waste depended upon the grade of the cotton —
the lower grades having many more seeds than the better ones.

In the seed recovered from the picker waste of 37 bales 15 dead pink
bollworms and 1 live one were found. The great majority of the seed
appeared to be uninjured by the compression of the cotton. Baled
cotton is therefore dangerous and the danger, of course, is greatest
in the case of mills located in the cotton belt where cotton fields are
frequently in close proximity. (See fig. 3.)

HIE PINK BOLLWORM.

Il the findings from the examination of the .:7 bales to which
reference has been made are used as a criterion it appears that over
16,000 live larvae of the pink bollworm are brought to the United
States each year and thai _'!•'_' are sent i<. the southern mills.

HOW THE INSECT INJURES THE COTTON.

Tl„

pink bollworm affects the production of cotton in Beveral

ways. First, a considerable number of squares and bolls

injured thai they fall to the ground. Tn cases of heavy infestation

50percen1 of the crop may be destroyed in this way. However, this

does not end w ith the falling off of a certain amount of the fruit.

A single lock of a boll may be infest
In Buch a case the remaining locks de-
velop hut the boll opens prematurely,
and the fiber is short and kinky. Thus
the grade of the cotton produced may
be affected materially. Moreover, the
work of the inseel I tins in the

fiber which also reduce the value of
the product. This is not of gn
importance in the case of certain
ptian varieties which produce
dark-colored lint, hut in thevariei
producing white lint, like the Ah;:
and the American upland and 8
Island varieties, this form of injury
would be important.

A further form of injury by the pink
bollworm i^ in relation to the seed.
Considerable attention was attracted in England during 1913 to
(he low yield in oil from the Egyptian seed which is milled in large
quantities in that country. Tt was found that the lessened amount
of oil expressed was due to the infestation of the seeds by this insect.
While the mills ordinarily obtain from 10 to 20 per cent of oil, the
amount obtained in 1913 was found to he reduced to from Hi to 17
per cent . Another form of loss due to the attack of the in- : 1 1 s t

the seed is the reduction in the percentage of germination. In many
cases the infestation must he SO high that at least double the usual
quantity of cotton seed musl he planted to obtain a stand.

The total amount of loss produced by the pink hollworm in any
community does not seem to have been determined. In practically
all countries where the pink hollworm occurs it is associated with
other species of insects which work in the bolls and squares of the
cotton plant, and the relative damage by these differenl inso

FlO.4— Pink bollworm: Pupa, ventraland lat-
eral views. Much enlarged. (Original.)

THE PINK BOLLWORM.

not !>e estimated. Wherever the pest is found, however, it is con
sidered to be an insect of great Importance. Tn Egypt in jDIo, ac-
cording to Gough and Storey,' the pink bollworm did more dam
than all other cotton pests combined. In the Hawaiian Islands,
where the pest was introduced within the last few years, it has spread
rapidly and has becomo by far the most important enemy of cotton.

FOOD PLANTS.

It is quite evident from the accounts given by different writers
that all varieties of cotton are attacked by the pink bollworm.
Careful experiments conducted in India
failed to reveal even the slightest indi-
cations of varietal resistance to the boll-
worm. It is therefore practically certain
that if introduced into this country it
would attack the Sea Island as well as
all of the upland strains of American
cotton.

Occasionally the pink bollworm appears
to attack other plants. In the Hawaiian
Islands, Fulla way reared it from Thespesia
populnea. In Egypt, Dudgeon 2 records
"til" (a species of Sesamia) and pome-
granates as occasional food plants.

LIFE HISTORY.

The eggs of the moth of the pink boll-
worm, which hatch in about 10 days, are
deposited singly on various parts of the
cotton plant. The minute larvae feed on
the leaf surface for a short time but very
soon penetrate to the interior of the cot ton
bolls, or "squares." The insect spends
about 20 days in this stage, becoming in its
mature larval form (fig. 1) about half an inch long. The general color
is pink, from which the popular name is derived. In this stage it
feeds largely upon the seeds, and when ready to transform to the
pupa occupies the hull from which the kernel has been devoured. In
examining Egyptian cotton received in this country the larvae were
frequently found to have caused two seeds to adhere closely together.
In fact it seems to be a definite habit of the larva in the last stage to
form a cell of two hulls. This, however, does not seem to be an inva-

FiG. 5. — Pink bollworm: Moth, or
adult, dorsal view. Much enlarged.
(Original.)

1 Methods for the destruction of the pink bollworm in cotton seed. Ministry of cotton culture, Cairo, 1914,

P.I-
» Agricultural Journal of Egypt, vol. 2, pt. 2, 1913, p. 4.

G THH PESTS BOLL.WOBM.

riable rule, aa pupa? (fig. 4) have sometimes bean found in the lint.
The pupal stage Laata for about 14 day-, after which the insect <• Images
t<> a moth.

DESCRIPTION

The moth (fig. 5) of the pink bollworm i^ about three-fourths of
an inch iu expanse, and the general color grayish brown with darker
blotches. On.- of the characteristic marking- is a large dark i
near the apex of the forewings, whereas the hind wing- are of a
uniform grayish color, [n this stage the inseel lives al leasl lOdi
probably considerably longer, and begins the deposition of eggs in
three or four days after it emerges from the chrysalis.

WARHI vr.TKV : i."\ l!;\ \n:\ 1 PI rliK : 1914

UNIVERSITY OF FLORIDA

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