208 



HYMENOPTERA. 



blossoms, which act, as applied to this instance of the fertiliza- 

 tion of flowering plants b}^ insects, has been called by Mr. 

 Westwood " caprilication." 



Cynipid^ Westwood. (Diploleparice Latreillo.) Gall-flies. 

 In this most interesting family we have a singnlar combination 

 of zoological and biological characters. The gall-flies are closely 

 allied to the parasitic Chalcids, bnt in their habits are plant- 

 parasites, as thc}^ live in a gall or tnmor formed by the ab- 

 normal grovrth of the A'egetable colls, duo to the irritation first 

 excited v/hou the egg is laid in the bark, or substance of the loaf, 

 as the case may be. The generation of the summer broods is 

 :ilso anomalous, but the parthenogenesis that occurs in those 

 forms, by which immense innnbers of females are produced, is 

 necessary for the work they perform in the economy of nature. 

 When v>-c seo a single oak hung with countless galls, the work 

 of a single species, and learn how numerous are its natural 



V. 



Jir. 





enemies, it becomes evident that the demand for a great nu- 

 merical increase must be met by extraordinary means, like the 

 generation of the summer broods of the Plant-lice. 



The gall-flies are readily recognized by their resemblance to 

 certain Chalcids, but the abdomen is much compressed, and 

 tinually very short, while the second, or the second and third seg- 

 ments, arc greatly developed, the remaining ones being imbri- 

 cated or covered one by the other, leaving the hind edges 

 exposed. Concealed within these, is the long, partially coiled, 

 very slender ovipositor, which arises near the base of the abdo- 

 men.* Among other distinguishing characters, are the straight 



*rig. 142. I, nbtlomcn of Cijnip.t quercus-aciculnta Osten Saoken, with the ovipos- 

 itor cxsertpd ; II, the same with the ovipositor i-etraeted; III, the abdomen of the 

 female of Figites (Diplolepis) Mineatus Say; IV, the same showing the ventral 

 portion, in nature covered f).v tlic tcr^jal portion of the abdomen ; V, end view of the 



