376 The University Science Bulletin. 



under identical external conditions. Very often a number of the 

 specimens attain full size, metamorphose, and produce young long 

 before others of the same generation. The majority, however, ma- 

 ture in about five months. 



THE EGG. 



The eggs are about % mm. in length and about Yq mm. in width. 

 They are oblong in shape and slightly arched. Not uncommonly 

 they were found adhered together in pairs. One end of the egg 

 usually has hair or threadlike projections. Each egg has a number 

 of ridges running lengthwise and crosswise (see plate XL). The 

 eggs are whitish in color, translucent, and the surface appears rough, 

 and is of delicate skin covering the aqueous interior. It is easily 

 broken. The filaments described at the end of the egg adhere to 

 any object with which they come in contact. 



MOLTING. 



I found without exception that there is much variation in the 

 rate of molting and the number of larval skins shed by the different 

 individuals of this species. Under normal conditions the larvae molt 

 twice in about every two weeks. Many peculiarities are worthy of 

 mention. The same specimen often sheds its skin irregularly, some- 

 times within ten days, and again, under the same conditions, not 

 until a period of three or four weeks has lapsed. The rapidly grow- 

 ing individuals molt more frequently than do those which have 

 about attained their full size. The specimens that are slow in de- 

 velopment molt less frequently than do the larvae which develop 

 at the average rate. The full-grown larvae previously spoken of, 

 which continue to live for a long time before entering the pupal 

 stage, have a decidedly slow rate of molting. The average rate is 

 about once in every three weeks, and there is a gradual decrease 

 as the specimen grows older. 



Thus I have found in all my observations that the number of 

 molts is by no means constant. As previously mentioned, the ma- 

 jority of specimens which complete their life history in about five 

 months, shed their skins from ten to fifteen times, whereas many 

 of the individuals with the prolonged larval history molt as often 

 as twenty times. 



The larva? never eat their own skins, nor the skins of other indi- 

 viduals of this species, even though they may be in the most extreme 

 stage of starvation. This was conclusively proven by placing speci- 

 mens in a glass vial for the purpose of starving the larvae, and after 



