[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 lengthy 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. H<5w 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. 



" T^he 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 S 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 ia 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 

 remaiu upon the stalks after the leaves were consumed in the year 1825. It is well 

 known, that 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 wary 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 com, 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 consequence 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 leaf 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 froih 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 retiring 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 they are also protected from the vio- 

 lence of the winds. . 



