88 REPORT UPON COTTON INSECTS. 



There has been some discussion respecting the natural position of the 

 moth while at rest. I found that in the field it almost invariably alights 

 with its head down, but the majority of specimens which I saw in houses, 

 when resting on the walls, did so with the head directed upwards. 



During the warmer part of the season the moths in confinement began 

 to oviposit within thirty-six hours after emerging from the pupa state. 

 During the autumn the time varied from four days to a week. The 

 greater number of eggs are laid during the night. As already stated, 

 the eggs are deposited chiefly on the lower surface of the larger leaves 

 on the middle third of the plant. This may be owing to the fact that 

 the moth is attracted to that part of the plant by the nectar glands 

 which are on the leaves. In fact, Mr. Trelease observed moths alter- 

 nately sipping nectar from these glands and ovipositing. During the 

 operation the moths flew from leaf to leaf and from plant to plant, each 

 moth depositing but a single egg on a leaf. Still, if we accept this as 

 explaining why the moths oviposit on that part of the plant, it is diffi- 

 cult to say why more eggs are not laid near the glands on the involucre, 

 which the moths also frequently visit. 



The number of eggs laid by a single moth probably varies from 400 

 to 600. September 11, I counted the number of eggs in the ovaries of 

 a female taken in the field. There were 400 well developed eggs and 

 284 immature ones. After that date I dissected many females, but 

 found only immature eggs. 



It is difficult to say how long this insect exists in the adult state ; 

 doubtless the time varies greatly with the season. Moths of the third 

 and fourth broods die in confinement within five days after their exclu- 

 sion from the pupa, while, as we shall show later, those of the last brood 

 remain alive several months. 



The number of broods of this insect in a single season, is also some- 

 what difficult to determine. For not only does the earliest brood ap- 

 pear at different times in different sections of the cotton belt, but in the 

 same locality different individuals of the first brood were found to vary 

 in age nearly two weeks. As a result of this variation during the latter 

 part of the season, examples of all stages were found at the same time 

 in the same field. Still a large proportion of the cotton-worms in a 

 given locality undergo their transformations at nearly the same time ; so 

 that broods sufficiently well marked for our purpose have been ob- 

 served. And we conclude that in those sections in which we believe the 

 moth to hibernate, there are each year at least six broods. By the 1st 

 of September of the present year (1879) larva* of the fifth brood (third 

 crop) were appearing in considerable numbers in Central Alabama. 

 Moths bred from specimens of this brood which were sent to this de- 

 partment began to oviposit October 10, and October 15 larva? of the 

 sixth brood began to appear. It is probable that the sixth brood ap- 

 peared at an earlier date in Alabama, the development of the speci- 

 mens in my breeding-cages being retarded by the low temperature of 

 the room in which they were kept. 



