304 REPORT UPON COTTON INSECTS. 



themselves into leaves folded arid pre-occupied by Alelia, the latter having already 

 passed into the pupa state, and they had done this for the express purpose of feeding 

 on these pupae. Many cases of this sort were seen. 



In the specimens sent to the department, the full-grown boll- worm 

 was found entirely within tlie folded leaf and the hind end of the body 

 of the chrysalis was eaten into ; and it certainly would be difficult to 

 account for this on any other grounds than those taken in the quota- 

 tion. We find also in the same report the following : 



No lepidopterous enemies of Aletia larvae were observed by myself, but Dr. Lock- 

 wood, of Carlowville, Ala., says that a number of years ago he saw a large green 

 larva devouring numbers of cotton- caterpillars. From what we know of the habits 

 of the boll-worm (Heliotliis armigera) it seems not unlikely that these larvae may have 

 belonged to that species. 



Judging from the data at hand, the duration of the larva state of 

 Heliotliis, or, in other words, the worm state, seems to vary from eighteen 

 to twenty -four days in the cotton-belt, depending much upon the climate, 

 the state of the weather, and the food plant. When full-grown it trans- 

 forms to a chrysalis, with very different preliminaries from those which 

 prepare the cotton-worm for pupation. 



THE CHRYSALIS. 



Almost all of the statements regarding the pupation of the boll-worm 

 have been to the effect that the full-grown worm descends into the 

 ground to the depth of several inches, and there forms itself an oval 

 cocoon of gravel and earth, cemented together by its gummy silk. 



Prof. G. H. French, of Illinois, has studied the chrysalis of Heliothis 

 carefully of late, and sums up his observations as follows : * 



In digging for the chrysalis around the corn-hills, I found that instead of their oc- 

 cupying an oval earthen cocoon, as has usually been written of them, and as they 

 apparently do in the breeding box, they were down in the ground from five to six 

 inches below the surface, in a hole about a third of an inch in diameter, reaching from 

 the chrysalis to the top of the ground, where it was covered with a thin film of dirt 

 from an eighth to a quarter of an inch thick. This hole was larger at the bottom than 

 at the top, apparently so as to give full motion to the chrysalis, and usually bent in 

 its course, so the lower part would have an inclination of perhaps forty-live degrees. 

 At the bottom would be found the chrysalis, the small end downward and the head 

 upward. In one case I found the hole so bent that the chrysalis occupied a horizontal 

 position. The hole was smooth inside, and was, perhaps, made so by cementing the 

 earth together, but of that I could not tell, for the whole ground was moist, though 

 dry enough to be firm. 



In reference to these observations of Professor French, Mr. Trelease 

 says, in a recent letter: 



In deep breeding-jars, with four or five inches of loose soil, I found that the larvae 

 of Heliothis went several inches from the surface before forming their cocoon, but did 

 not notice a passage leading down. As I did not notice very closely, such a tube may 

 have been there, but I think if so I should have seen some trace of it. In all cases 

 there was a thin film of silk. In the field I saw numbers plowed up, but did not dig 

 for any with care. Of course the plowing would have destroyed such a tube, but I 

 sometimes found the silk about the pupa, though always more or less torn. 



Seventh Report of the State Entomologist of Illinois, 1877, p. 105. 



