230 THE ENTOMOLOGIST. 



About July 12fch specimens of Pachynematus obductus went 

 into litter, spun cocoons and kept as noted above. On July 

 25th a green female pupa was found on the surface, where it lay 

 2 days before adult activity. No other specimens behaved so. 



These laboratory results are too insufficient to warrant much 

 comment. In no case was the metamorphosing insect disturbed. 

 The appearance of A. serotinus on the surface could be explained 

 on the grounds that the pupa, unencumbered by a cocoon, by its 

 wrigglings — pupse at times do wriggle vigorously in a corkscrew 

 fashion — managed accidentally to reach a higher level. But in 

 the other two cases explanation is not so ready because the 

 specimens belong to cocoon-forming species. Unfortunately my 

 notes do not record any facts as to the condition of the cocoons, 

 so the significance of these emergences remains obscure. Either 

 the specimens spun feebly, in which case the cocoon-spinning 

 instinct is liable to vary, or the pupse were able to free themselves 

 prior to adult activity. If the former happened emergence could 

 be explained by pupal wriggling ; if the second, the conditions 

 governing emergence required further investigation. Under 

 natural conditions, unless some superficial shelter were obtained, 

 this faculty would be of very doubtful survival value to the 

 individual or species. The phenomenon does not appear to be 

 sexual. MacGillivray (3), whose papers came into my hands 

 since writing these notes, has already had similar experience, on 

 which he writes : "Just before they are ready to cast their larval 

 skins and become pupse, they may leave their cocoons or earthen 

 cells or tunnels in rotten wood and force themselves to the 

 surface of the soil, where they will remain as if dead, only 

 wriggling the body when disturbed. Such may pupate . . . 

 and produce adults or they may die." As I only observed pupse 

 on the surface, I cannot give any information regarding the 

 behaviour of the larvse. 



Emergence of the sexes. — Attention in the following instances 

 has been confined to experiments in which I have reared the insects 

 from fair numbers of eggs or larvse. The number of emergences, 

 however, is somewhat small. Females emerging first: P.pavida, 

 4 females out August 7th to 14th, 1921, then 4 males August 

 15th to 26. P. luridiventris, 4 females out June 18th to July 4th. 

 No males. There is good reason for thinking that N.fuscipennis 

 and A. vittatus behave similarly. Males emerging first: A. serotinus, 

 2 males out September 18th, 25th, 1 female October 5th. 

 P. ruficornis, 1 male July 13th, 2 females July 15th, 19th. 

 P. pallipes, I male April 3rd. First females June 21st. (Miss 

 E. F. Chawner's experiment.) 



Sexual Behaviour. 

 While visiting the Edinburgh Botanical Gardens on Sep- 

 tember 7th, 1921, a very hot day, a large number of Athalia 



