ORDER HYMENOPTERA. 



27 



Tribe IL — Entomophaga. 



Most of the insects belonging to this tribe are parasitic on other 

 insects. The larvce are footless. There are seven families in- 

 cluded in the Entoviophaga. 



Family 18, Cyjiipidce. — This family includes most of the gall 

 flies. The number of species is very considerable. Of the great 

 majority the females pierce with their ovipositor the tissues of 

 plants and trees, and there deposit their eggs, from which the 



Fig. 29. — Cynips Gallae Tinctorise (Mag.) 



larv(E are soon hatched. The irritation caused by this intrusion 

 of a foreign body into the tissues produces the galls which are so 

 commonly met with. 



The galls produced by different species of flies differ greatly 

 in form and structure. Some of them are round and smooth, like 



Fig. 30. -Smicra Sispes (Mag.) 



fruits, such as the cherry gall of the oak leaves, produced by the 

 puncture of Cynips querciis-foli. 



The most singular, however, of all the galls is perhaps the 

 Bedeguar, which is formed on the stems of wild roses by the punc- 

 ture of a small species, Rhodites roscc. 



