PARASITE BEHAVIOUR 363 



The Behaviour of Adult Parasites 



Feeding Behaviour. Little definite information exists relative 

 to the feeding habits of many groups of adult parasites ; there 

 are a number of species which may be reared under experimental 

 conditions, where they freely mate and deposit their eggs in the 

 normal manner without food, owing perhaps to the exigencies 

 of the reproductive instinct. The vast majority of the 

 Ichneumonoidea, and probably all the Tachinidae, occur freely 

 in the open and are very constant visitors to umbelliferous 

 and other flowers. On the other hand, there are many parasitic 

 Hymenoptera which never appear to frequent flowers, and 

 probably subsist upon honey-dew and other organic material 

 available. 



A phenomenon first noted by Marchal in 1905 in the Chalcid 

 genus Tetrastichus, and frequently recorded in other Hymenoptera 

 by subsequent observers, is the habit of feeding upon the blood 

 of the same, or another, individual of the species which is destined 

 to serve as the host for the offspring. In these cases the actual 

 feeding takes place at punctures made by the ovipositor through 

 which the blood of the victim exudes. It is possible that 

 nitrogenous food of this kind is necessary to ensure complete 

 maturation of the eggs, but whether or not this is the correct 

 explanation, the habit is prevalent in many species. The punctures 

 may be made in the eggs, larvae, pupae or adults of the species 

 attacked and, when expressly made for feeding purposes, 

 oviposition often takes place in another individual of the same 

 species. Not infrequently a number of individuals may be 

 punctured in succession without any deposition of eggs taking 

 place. Muesebeck and Dohanian (1927) are among the most recent 

 observers of this behaviour, and they state that it prevails among 

 nearly all the parasites of Apanteles melanoscelus, a primary' 

 parasite of the gipsy moth. The habit is sometimes so extensive 

 that the entire fluid content of the Apanteles may be consumed, 

 and in other instances, where oviposition has followed, the young 

 hyperparasitic larvae perished through insufficient nutriment being 

 afforded by the primary parasite. These observers consider 



