40 THE CANADIAN ENTOMOLOGIST. 



its dark abode. The mouth is filled with a blackish fluid when withdrawn 

 from the feeding spot. If gently touched, the head and fore part of the 

 body would be raised, a? stiffly as consistent with such a soft insect, and 

 this posture maintained for some moments. 



The little animals were carefully watched and examined several times 

 a day, until finally the larger one, having withdrawn nearly all the juices 

 from the pupa and become swollen to an unwieldy size, changed, after a day 

 or two of resting, into a pupa — still in the original cell which I had removed 

 from a stone and turned upside-down for more convenient examination. 

 The smaller one was restless and refused to finish its feeding on the original 

 pupa, so, as it had apparently not completed its growth, I tried it with a 

 fresh one of Tropisternus glabej-, which was immediately accepted as a 

 substitute. The first pupa was probably spoiled, either by mould or 

 bacterial decomposition, hence the necessity for fresh food in this instance. 

 As soon as the larva had completed its growth I consigned it to the 

 alcohol bottle for study. 



How the Brachinus gets into the cell of its host, whether brought as 

 a young larva clinging to that of Dineutes, or deposited as an egg by the 

 mother, is a mystery to me. When small it is more active than when 

 larger grown, and with advanced age becomes gradually more helpless. 

 In any case the complete adaptation to a parasitic habit is apparent in 

 the whole structure — the soft, juicy body, unprotected by chitinous scutes, 

 the weak legs, quite useless for ambulatory purposes, and the lack of 

 strong, locomotive bristles. The appearance is almost that of some 

 Hymenopteron, not at all resembling the strong raptorial larvse of 

 Adephaga in general. I cannot believe that the larvae of all our American 

 Brachinus live on Dineutes, but it is quite possible that they feed on the 

 helpless pupae of such other Adephaga as frequent the damp spots 

 favoured as habitations by these beetles. Perhaps some of the readers of 

 the Canadian Entomologist may be induced to investigate the matter, 

 or to make known the results of study if the investigation be already made. 



While two Dineutes pupse were infested as noticed above, another of 

 the same species was seen to be the abode of several little maggots, which 

 soon changed to small black pupae, loose in the cell, without spinning 

 cocoons. From these I finally got four specimens of a small Chalcid, 

 eleven or twelve days after I first noticed the larvae, which, however, were 

 nearly full grown at that time. From Mr. Ashmead, to whom I sent the 

 little insects, I hear that they belong to the genus Cyriogaster, not 



