114 THE CANADIAN ENTOMOLOGIST. 



but the stigmata are not so large, and the basal area is never white, 

 while there is much difference in the genitalia of these two. 



The larva belongs to that group having only the dorsal line 

 entire, and has been discussed in the paper referred to. The 

 characteristic gall produced in the stem of the vine seems always 

 to furnish a restricted food supply, except when very large vines 

 are chosen. But one gall is made as it is impossible for a larva 

 to re-establish itself a second time due very shortly to their increased 

 size, and some seem to perish from the gall becoming too small 

 to shelter them, or upon splitting open adversely. Parasitism does 

 not appear to be pronounced, but the insect fauna of these galls 

 is always noticeable. The larvae of several small dipterous species 

 flourish in the chewed fragments and frass, especially in deserted 

 galls, and the imago of a deltoid moth, Palthis asopialis Gn. has 

 several times been reared from a larva feeding upon and having 

 pupated within a gall. It seems improbable this common species 

 is dependent on hunmli galls for food supply, but that its associa- 

 tion with Hop may be along more usual lines. The Cecidomyid, 

 Lasioptera humulicaulis Felt, produces a similar gall, at times very 

 much larger, up to 50 cm. in length, and frequently on the same 

 stem with hiimnli. Even then the vine manages to thrive very 

 well. 



Since the association of a particular food plant is so noticeable 

 with most Papaipema species, and may have had much to do in 

 helping fix specific modifications, it seems reasonable to assume 

 these associations date back remotely. It is true some Old World 

 plants may serve as a substitute for this North American genus, 

 Arctium meeting the cosmopolitan taste most conspicuously, but 

 in nearly every case an indigenous, preferred food plant is very 

 apparent. So that in advancing a name at this time we consider 

 the Hop as indigenous, notwithstanding some botanists have 

 designated it as introduced. The insect fauna of Humulus hipidus 

 is a \evy considerable one and seems a fact worthy of weight. 

 That such a large number of species subsist on it would not be 

 likeh" if introduction had occurred since pre-Columbian times. 

 We note Britton and Brown in Illustrated Flora, 1913, cite the 

 plant as widely distr buted throughout the north temperate zone. 



