1918] 



Scirtes Tibialis, Guer. 



395 



made and the stadia lengths were noted (m a series of tables) 

 1^ days but also in half days and shorter intervals where 

 possibl: The average length of the stadia for all the individuals 

 in a group are given in the following table: 



There is some apparent regularity in tliese stadia lengths, 

 but not enough for drawing exact conclusions^ Especially is 

 this true of the latter ones because of the many fatalities caused 

 largely by molds, that occurred in an increasing rate. As a 

 result these latter stadia are represented by only a few mdivid- 

 uals. In group 1 unfortunately all the larvae except one were 

 killed by mold early in the second stadium, sharing the fate of 

 groups 2 and 3; but this one survivor lived through its seventh 

 ftadium and di:ed in its eighth. Thus of group 7, all the larvae 

 died before they had completed the second stadium and of 

 group 4, before they had completed the 6th stadium. Observa- 

 tions te;minated in the middle of September. Since work could 

 not be continued during fall and winter, further data of ecdyse 

 and growth and the exact manner of over-wmtenng, could not 

 be ascertained. An unsuccessful effort was made to determme 

 the winter condition of the larvae when I resumed work m 



^'^The first larva found in Spring (1918) was on May 4 at 

 which time just a few new Lemna leaves had come to the sur- 

 face, (having developed from bulblets, which overwmter at the 

 bottom) Though the food supply was 3ust as meagre May 11, 

 twelve larvae were secured, and they were becoming increas- 

 rgly more abundant in the upper water. This represents then 

 the time of resumption of growth and activity. The seventh 

 instar, the last reared the preceding August, was oiUy three- 

 tenths as long as the average full grown larva. Some of the 

 "obtained in May were no larger, but they varied from 



