CLASSIFICATION AND DESCRIPTION OF COMMON INSECTS 351 



Thalessa lunator, a slender, brown and yellow, wasp-like Ichneumon 

 with a long delicate ovipositor. 



Pupa. — Formed in burrow within a cocoon made of silk and chips. 



Cynipid^ (Gall-flies) 



The injury done by Cynipids to economic plants is not serious, 

 being confined mainly to oaks and roses. (Consult Felt's Key to 

 American Insect Galls). 



Eggs are laid in the leaves, stems and roots, and soon gall-like en- 

 largements are formed as a result of 

 the stimulus of the larvae. The galls 

 are closed and are very varied in 

 shape. 



The Mossy Rose-gall on Sweet- 

 brier, produced by Rhodites rosce 

 Linn., is many-celled and consists of 

 a number of hard kernels embracing 

 the stem, covered with reddish-green 

 mossy filaments. 



The Pithy Blackberry-gall, pro- 

 duced by Diastrophus turgidus on 

 blackberry canes consists of an elon- 

 gated, many-celled, ridged, woody, 

 reddish-brown gall. 



Pithy Blackberry-gall Fly {Dias- 

 trophus turgidus Bass.). Adult. — Black, 1^2 inch long; feet 

 antennae red; four wings, transparent and almost without veins. 

 Early summer. 



Larva. — White, 3^fo inch long, mouth-parts and spiracles reddish; 

 hibernates in cells of gall. 



Pupa. — Formed in spring. 



Control. — Cut out and burn infested canes during the winter. 



Several species infest oaks, viz., Amphiholips spp., Holcaspis spp., 

 Andricus spp., and Cynips spp., each producing its characteristic gall. 



PROCTOTRYPIDiE (PROCTOTRYPIDS) 



The members of this family, or rather the group Proctotrypoidea, are 

 the smallest of insect parasites. They are usually black and without 



Fig. 234.— Pigeon tremex (Tremex 

 colutnha): A, adult; B, larva (with 

 parasitic larva of Thalessa attached). 

 Natural size. {After Riley.) 



and 



