﻿LARVAL AND PUPAL STAGES IN SOME OF THE SESIID^. 11 



searched birch stumps during last two weeks of July, and failed 

 to find a single larva or pupa. I also stripped numerous birch 

 stumps during March that had been cut during the winter of 

 1911-12. I saw plenty of old burrows, but failed to find a single 

 larva or pupa in them. From this I conclude S. culiciforniis, 

 like S. cynipiformis, has only a one-year cycle from egg to insect. 

 S. myojnformis, though not rare, is more difficult to obtain. 

 I searched old apple trees and found ten larvae that looked like 

 being full-fed. This was in April. These I also forced, putting 

 them in apple sawdust and bark ; they pupated at once, and in 

 due course emerged, eight nice specimens. At the same time I 

 found on other apple trees some seven or eight smaller larvae, 

 obviously not full-fed. I endeavoured to rear these, but all 

 died. Of these seven or eight larvae some were about a quarter of 

 an inch long when found, others up to half an inch, but I never 

 found small, and what I considered to be full-fed, larvae on the 

 same branch or on the same tree. I again searched the trees 

 on which I had found full-fed larvae during the last week in 

 June, but only found empty pupa cases. From this I conclude 

 that the larval stage of S. myopiformis lasts longer than one year, 

 and probably two years in all. 



Not far from here I obtained thirty-five larvae of *S^. andrence- 

 formis during April, 1914. I split open about half the sticks to 

 examine the larvae, closing them up again carefully. I kept the 

 sticks in moist sand, and in due course bred out twenty-one 

 imagines and three ichneumon. The remaining eleven larvae 

 fed for some time, but when the wood dried they came out of 

 their burrows and crawled about cage till they died. These were 

 almost as large as those that were full-fed. I also, in other 

 sticks that I split without cutting from bush, saw some quite 

 small larvae less than a quarter of an inch long. I tied up twigs 

 and left them. When first found the full-fed larvae were fat, 

 dead-white in colour, and resting head towards exit hole, but 

 with no signs of cocoon. I did not see when they spun up, 

 but one or two I looked at shortly before they emerged were 

 in pupal stage. From the fact of finding larv^ in three stages, 

 full-fed, large, and small, I think we may safely assume that 

 the larval stage lasts at least two, and probably three, years. 



Owing to feeding in stems of currant bushes, S. tipidiformis, 



though common, is hard to obtain. In the small extent of 



currant bushes to which I have access I found ten larvae in 



April. Four died in larval or pupal stage and six emerged. 



All were found in bushes that had been heavily pruned the 



previous year, so the eggs could not have been laid or larvae 



>io>-esent earlier than 1913. No small larvae were found any- 



\^Oere in the garden ; all were apparently same age. I do 



e^** think there can be any doubt that the life-cycle does not 



nd beyond one year. 



