158 



FOREST ENTOMOLOGY. 



1895, and again fairly abundant in 1896. In 1897 I found one as 

 late as May 23 in Cheshire, and it hatched out next day. It may be 

 found either singly or in masses, and each gall is single-chambered. 



The perfect insect is one of the prettiest of the gall-flies. The head 

 and thorax are black, and abdomen of a bright shining appearance. 

 The wings are considerably longer than the body, and the general 

 appearance handsome and slender. Having observed that the fly from 

 B. renum on the leaves was apterous, contrasted with long-winged flies 



from Trigonaspds megaptera, 

 it may be observed in passing 

 that the apterous flies deposit 

 their eggs on adventitious buds 

 on the stem from one to three 

 feet from the ground. 



There is another curious 

 point worthy of notice. 

 Cameron gives Trigonaspis 

 megaptera as the agamic form, 

 and Biorhiza renum as the 

 sexual. Adler, on the other 

 hand, gives Trigonaspis meg- 

 aptera as the sexual, and 

 Biorhiza renum as the agamic 

 form. Cameron describes the 

 male of Biorhiza renum, and 

 Adler describes the male of 

 Trigonaspis megaptera under 

 the synonym of Trigonaspis 

 crustalis, Htg. 



Perhaps the inference 

 which might be drawn from this apparent contradiction is, that 

 while the various families of insects appear to be well worked by 

 leading authorities, it is nevertheless essential in practical entomology 

 that all points should still be verified. 



Fig. 156. Galls 0/ Cynips Kollari (marble gall). 



Cynips Kollari (Htg.) 



The next and last species I shall deal with is the very common 

 one known as "marble galls" or Cynips Kollari, often very abun- 



