PROC. ENT. SOC. WASH., VOL. 24, NO. 2, FEB., 1922 37 



this point is apparently to be found in the Cynipoidea, another 

 group containing both parasitic and phytophagous forms. 

 While it is probably not possible to point to any one structural 

 character or group of characters which will separate the para- 

 sitic Cynipoids as a whole from the gall-making forms, it is 

 nevertheless true that certain more or less definite structural 

 groups are always parasitic while others are always phytopha- 

 gous and one is able to determine with considerable confidence 

 from examination of any given specimen whether it is parasitic 

 or phytophagous. This does not warrant the assumption that 

 phytophagy even among the Cynipoids is a continuation from 

 ancestral type but certainly does seem to indicate that it has 

 longer existed in this group than in the Chalcidoids. 



Parasitic forms of the Chalcidoids have been shown to possess 

 to an extremely high degree the ability to adapt themselves to 

 different environmental conditions. Not only do they attack 

 successfully all manner of insect hosts under almost every con- 

 ceivable condition as regards environment, but they attack 

 them in the egg, larval, and pupal stages, and they may be either 

 primary parasites or hyperparasites. Some individual species 

 are not confined to a single host or to closely related hosts but 

 live at the expense of widely different hosts, in some cases 

 embracing even different orders. Several instances are known 

 of species that develop either as primary or secondary parasites 

 as circumstances determine. Considering these facts it seems 

 certain that if phytophagy had long existed it would be found 

 much more common than at present seems to be the case since 

 there appears to be no good reason why the phytophagous 

 forms should be more restricted in their powers of adaptation 

 than the parasitic forms. 



The most important point confirmatory of the probable 

 recent development of phytophagy among Chalcidoids is found 

 in the assertion by three different authors that certain species 

 of Eurytomidae are parasitic in their early stages and finish 

 their development as plant-feeders. Nielsen has claimed 

 this to be the habit of an unnamed species of Eurytoma; Rimsky- 

 Korsakov has recorded the same habit for Harmolita hiquUhntm; 

 and Phillips asserts that Eurytoma pater follows the same mode 

 of development. There is evidence that this phenomenon 

 may occur in the development of other Chalcidoid species, 

 notably with some of the gall infesting species which have 

 been supposed to be commensals. Such a mode of development 

 if proven to be at all common would seem to leave little room 

 for doubt that phytophagy is a recent specialization. 



On first thought the transition from a parasitic to a phyto- 

 phagic existence would appear to involve an extremely radical 

 ecological readjustment. One must, however, bear in mind 

 that these now phytophagous species were, as shown by their 



