HYMENOPTERA. 125 



that of a small artichoke, etc. etc., one cannot say. 

 The problem still remains to puzzle us. 



The Naturalist after collecting a number of galls, 

 for the purpose of discovering the various kinds of 

 Gall-fly inhabited by them, cannot be sure that the 

 little insect he sees to emerge from its place of conceal- 

 ment, is the original and lawful occupant, for there are 

 various kinds of Ichneumon flies, which in their turn 

 pierce the body of the young Gall-grub wherein they 

 deposit an egg, from which is produced a parasitic 

 Ichneumon, which feeds on the young Gall-grub, and 

 eventually comes forth from the same hiding place. 

 The Gall-flies are small insects, the largest species 

 known in England being the Cynips Kollari, already 

 noticed. 



I ought to notice that both in the Saw-flies and the 

 Gall-flies the males seem very rare. Mr. F. Smith once 

 collected about a bushel-and-a-half of the galls of C. 

 Kollari, for the purpose of finding a male. None but 

 females made their appearance. Yet when he placed 

 the female flies in various places, on oak trees, and 

 visited them afterwards he found new galls on those 

 trees, but on no others in the neighbourhood. Here is 

 an instance of parthenogenesis, evidence of the existence 

 of which in the Cynipidce has lately been commented 

 upon by Siebold, who has also considered the fact of 

 the rarity of the male. Many species of the Tenthredinse 

 (Saw-flies) exhibit the same phenomenon. 



The Ecaniidce are most extraordinary looking 

 insects ; the family contains only a few species, which 

 are parasites on cock-roaches (Blattse). Evania ap- 

 pendigaster has an enormously developed thorax, and 



