202 The Ohio Journal of Science [Vol. XVIII, No. 6, 



Pupa. — Directly after completing the cocoon, the larva 

 becomes quiescent, and within one or two days assumes a 

 straight, rigid shape, becoming a prepupa. After five to seven 

 days pupation occurs, the larval skin being pushed down into 

 the bottom of the cocoon as a tiny crumpled mass. The 

 time spent in the pupal stage varies greatly — from three to 

 five weeks with different species. At the end of this time, the 

 adult issues, but does not as a rule emerge from the cocoon 

 until two or three days later. It then chews its way out at or 

 near one end, and is ready for active life immediately. The 

 total life cycle varies from a year to as low as forty-three days. 



SEASONAL HISTORY. 



Hibernation. — All species of the dryinids studied by the 

 writer have so far passed the winter as larvae within the cocoon ; 

 and this is probably true of the great majority of them. A few 

 got as far as the prepupal condition, but all larvse collected in 

 September and late August remained as such. There seems to 

 be no difference in the structure of the winter and summer 

 cocoons. 



Generations. — The number of generations a year depends 

 upon the species of host attacked, and of course upon the 

 climate. Species attacking a host that has two generations a 

 year— as with Gonatopus erythrodes (Perk.) parasitic on Delto- 

 cephalus inimicus — have the same number of generations. 

 Others have but one. Two generations a year seems to be the 

 maximum in this latitude, though farther south there are 

 probably more. When a species attacks but one stage of its 

 host, it must spend most of the year in the cocoon, issuing only 

 when the right stage of its host is present. In one case, that of 

 Chelogyniis chlorotettixi n. sp. parasitic on Chlorotettix unicolor, 

 the nymphs of which are found only in June in the Lake Erie 

 region, spins its cocoon in early July and remains as an active 

 larva within its cocoon throughout the remainder of the summer 

 until the next spring, when it pupates and emerges in June in 

 time to attack the nymphs of its host. One cocoon of this 

 species was carefully split open in September, and an active 

 white larva revealed. Later it was noticed that this larva 

 had spun over the slit in its cocoon. 



In some cases, where there are two generations a year, 

 part of the larvse of the first will pupate and the rest will remain 



