COKKELATION OF TAXONOMIC AFFINITIES 

 WITH FOOD HABITS IN HYMENOPTERA, 

 WITH SPECIAL EEFERENCE TO > 

 PARASITISM^ 



PROFESSOR CHARLES T. BRUES 



Entomologists can all agree that tlie attachment of 

 most phytophagous species belonging to the more highly 

 specialized orders of insects is very firmly fixed, and the 

 Hymenoptera form no exception. We can also agree, 

 although in less definite terms, that many parallels exist 

 among plant-eating Hymenoptera between taxonomy and 

 food habits. I do not propose to treat of this series, 

 however, partly because I am not sufficiently familiar 

 with them, but also on account of the great interest which 

 attaches to the parasitic groups of Hymenoptera. 



During the last decade our conception of the process 

 of nutrition in insects has undergone considerable change, 

 due to the discovery that various microorganisms form 

 an important part of the food supply of many forms. 

 It is quite certain that certain saprophagous, sarcoph- 

 agous and coprophagous ones probably feed directly, not 

 at all upon decaying and fermenting plant materials, 

 carrion or excrement, but upon the bacteria, yeasts, etc., 

 always abundant in organic material undergoing decom- 

 position. We must judge of the protein requirements of 

 such insects not by the gross substances or substratum, 

 but on the basis of the microorganisms present (Baum- 

 berger, '19). 



This aspect does not appear to enter into the economy 

 of the Hymenoptera, although there may be a relation 

 between fungi and nutrition in some Cynipidae, as the 



tion, Harvard University, No. 181. 



134 



