1911] Girault, Species of Trichocjranimatihe (Hymenoptera). 161 



Thus this parasite attacks four orders of insects, including 

 eighteen families and thirty-eight genera, but the largest number 

 of its hosts are lepidopterous ; in this connection, it should be 

 pointed out that those of its hosts which are hymenopterous be- 

 long to a group which certainly approaches the Lepidoptera in 

 many waj s and of all Hymenoptera are those most closely related 

 to moths and butterflies ; its coleopterous hosts also remind us ot 

 the Lepidoptera because of the form of their larvae and the leaf- 

 mining habits of the latter. All of its hosts have larvae which 

 are eruciform and all have indirect or complete metamorphosis ; 

 also all feed upon the foliage of various trees and plants — none 

 are woodboring insects or carnivorous or predaceous in their 

 larval stages. More significant still is the fact that all of its hosts 

 have eggs which are comparatively delicate or unarmed or with 

 conspicuous micropyles and which are deposited in exposed situa- 

 tions or at least in those which are accessible. 



The ecological relations of minutum are varied. It is a general 

 parasite and has therefore a wide choice of food ; hence as a 

 parasite and as an animal it must be highly adaptive and very 

 successful. Not being dependent upon any single source of food 

 (host) its reproductive rate does not have to be adapted to any 

 single condition ; its rate of reproduction must be an average in 

 relation to the average rates of reproduction of its group or 

 groups of hosts. If through fluctuation, a decrease in numbers 

 of one of its hosts occurs, in the same locality it can readily 

 change to another and thus is not likely, on the whole, to lack an 

 optimum supply of food for its progeny at all times. Its rate of 

 reproduction must therefore be an approximately stable, nonfluc- 

 tuating one, since it must, on the whole, so balance it that the 

 group of its hosts taken as a unit does not suffer. Moreover, this 

 parasite has an advantage in preying upon hosts which, many 



