[98] REPORT 4, UNITED STATES ENTOMOLOGICAL COMMISSION. 
each time in such wonderful progression, as would soon overwhelm everything by the 
increase were there not certain causes by which they are destroyed, and once more 
brought back within more reasonable limits. 
" The moth will be noticed the first in the series. It is a small insect of a triangular 
form, about 1 inch in length, and is easily distinguished from all others which bear 
any resemblance, by the peculiar dark spot upon its superior wings. It seldom 
moves in the day-time unless disturbed, but at night its flight is rapid, and it is often 
attracted into houses where there are lights. How many days after leaving the 
pupa state, it is before the moth lays its eggs, or how many of them, I am unable 
to say. 
" The egg is of a bluish green, and quite small. It is generally deposited upon the 
under side of the cotton leaf, and is about fourteen or fifteen days in hatching. It is 
confined to the leaf by means of a small filament, attached by a glutinous substance. 
" The caterpillar or larva, when hatched, is so extremely minute, as to be scarcely per- 
ceptible to the naked eye. In a few days, however, it attains its full size, which is 
about 1^ to 2 inches in length, and about the thickness of a crow quill. The color is 
not always the same— some being much darker than others. All, however*, are marked 
with black spots upon the back, and lines of the same color running the whole length 
from head to tail. The belly is of a light greenish yellow, and when about to web, it 
swells, loses the spots, and becomes of the same colour as the belly. As I before no- 
ticed, the sun appeared to have great effect in changing the color, or it was produced 
by the scantiness of the food, as it was only those of a light color who were able to 
remain upon the stalks after the leaves were consumed in the year 1825. It is well 
known, (hat the caterpillar avoids the sun, and it is principally in cloudy and damp 
weather, and during the night that they thrive best, and consume most food. At 
such times, when they are in large numbers, they can be heard at the distance of 
several yards whilst feeding and moving about on the cotton plant; and so offensive 
is the effluvia arising from them that this is generally the first indication of their 
presence, and so peculiar is it, that whoever has noticed it once will rarely mistake 
it when he again approaches them. Their activity, also, is remarkable. Upon being 
touched they double themselves up, and spring to some distance. In feeding, they 
always commence with the upper leaves ; afterwards they take the larger leaves, and 
finally, the blossoms and young pods, and in 1825 they were compelled to resort to 
older pods and the bark of the stalks. I have never seen them eat any food besides 
the cotton plant. In the year just mentioned, when they had completely denuded 
the cotton fields, excepting a few spots as before noticed, and were compelled to quit 
for the want of sustenance ; .they took their way through the corn-fields, pea, and 
potato patches; and although they webbed in each, and all of them, indiscriminately, 
yet the greater part perished on the earth for want of food. We may therefore con- 
clude, that these insects never devour anything but the cotton plant; and that the 
caterpillar which destroys the corn, the potatoes, peas, and grass, are totally differ- 
ent, as any one may see, who takes the trouble of examining them. The latter re- 
sembles it more closely than any other, but it is of a much lighter color, and although 
nearly as large around, is not more than half the length. The rapidity with which 
these insects increase, and the short time it takes to consume a large field of cotton, 
is truly astonishing. They not only do material injury to the cotton plant, by de- 
stroying the young fruit, but by the destruction of the leaves, the plant itself is 
injured, or a new growth caused, which essentially injure the larger pods, causing 
some to open prematurely, and others, in cousequence of a want of sap, to perish 
without ever expanding. 
"Added to this, they injure the ripe cotton, by the dirt and filth which they cause, 
and by webbing in the cotton itself, as they frequently do, either stain it by being 
mashed in it, or when hatched, the shell of the pupa remains, and passes through the 
gin rollers along with the cotton. In about fifteen days they begin to swell, and 
rolling up a loaf by means of filaments which they attach to it, they completely en- 
velope themselves, and in this manner pass into the pupa. It is not a matter of any 
consequence what leaves they use, but in general they resort to the cotton leaf, or 
those growing in its neighborhood ; and it is not an uncommon thing to see several 
thus webbed on one leaf, or to see a twig where every leaf has one embedded. 
" The pupa is of a dark chocolate or chestnut color. When touched, if alive, it al- 
ways moves its joints. They remain in this state from fifteen to eighteen days, when 
the moth makes its appearance. This is during the summer; but when they web, 
for the last time in the fall, the larva retires to the woods or some convenient place, 
where, uniting several dried leaves, it attaches them to a limb by means of a filament, 
2 or 3 feet in length, and retiriug into its cell, passes into the pupa, which remains in 
this state until the ensuing spring. The exact period of their hatching, varies accord- 
ing to the temperature of the winter and spring mouths; and it is undoubtedly for 
this reason that they retire to the woods, which being of a more equal temperature, 
does not expose them so much to the cold, and thoy are also protected from the vio- 
lence of the winds. 
