35 



smooth. The ridges on the dorsum appear to be formed largely of fat 

 tissue. After becoming full-grown the larva ceases to feed, the 

 alimentary canal becomes emptied, and both the color and form of the 

 larva are slightly changed. The dark color disappears from the inte- 

 rior and is replaced by a creamy tint from the transforming tissues 

 within. The ventral area becomes flattened, and the general curve of 

 the body is less marked. Swellings may be seen on the sides of the 

 thoracic region, and when these are very noticeable, pupation will 

 soon take place. 



GROWTH. 



It is impossible to follow the growth of an individual larva without 

 interfering so greatly with its normal conditions of life as to make the 

 observations unreliable. It seemed more accurate to measure larvae of 

 approximately known ages. In these measurements the natural curve 

 of the body was not interfered with, but the measurement taken across 

 the tips of the body as curved. In this way it was found that in squares 

 during the hot weather the length of the body increases quite regu- 

 larly by about 1 mm. a da}^. As it becomes cooler the daily growth 

 is less. In bolls which grow to maturity the rate of growth is less 

 and the length of the growing period is much greater. Full-grown 

 larvse vary in length from 5 to 10 mm. across the tips of the curve. 

 Larva? of normal size in squares average from 6 to 7 mm. The largest 

 larvae are developed in bolls which grow to maturity (Fl. Ill, fig. 13). 



MOLTS. 



To accommodate the rapid growth of the larva two or three molts, 

 occur. The period of change from one instar or stage to the next is 

 so short that the chanees of opening a square at just the righf time to 

 observe the process are very small indeed- However, it has been ascer- 

 tained beyond question that two molts occur before the larva reaches 

 half its growth. The first occurs at about the second day and the 

 second at about the fourth da}^. Whether a third molt occurs 

 before pupation can not be positively stated; but having occasionally 

 found larvae which had certainly just molted, but which were much 

 larger than the usual size at the second molt, the writer is led to sus- 

 pect that three larval molts may sometimes, though possibly they do 

 not alwa}^s, occur. In bolls where the length of the larval stage is 

 often three or four times as great as that usually passed in squares it 

 seems almost certain that more than two larval molts occur regularly. 

 Counting only the first two molts which have been often found, a third 

 occurs at the time the larva pupates. 



PROCESS OF MOLTING. 



So little is known in regard to the molting of Curculionidae that the 

 process as observed is here recorded. In the cases observed, starting 



