212 



INSECT TRANSFORMATION 



paired spiracles along the body-segments and on the ventral 

 aspect of the prothorax a characteristic sternal process or 

 ' breastbone ' (d), a little anchor-shaped sclerite, which 

 differs in its exact form in the various species. The larvae 

 remain in the galled buds through the winter and pupate there, 



FIG. 107. WILLOW GALL-MIDGE (Rltabdophago, hcterobia). 



a, female (side view) ; b, larva (side view) ; c, larva (ventral 

 view). x 50. d, anchor-process of larva, x 150. From 

 Carpenter,"con. Proc. Dublin Soc. I. 



the little, hairy, black midges emerging in the ensuing year. 

 The gall-midges may be recognized by the very simple nervura- 

 tion of the wing ; the female (Fig. 107 a), as is the case in many 

 other Diptera, has the hinder segments of the abdomen protru- 

 sible, so as to form an elongate "ovipositor", but this has no 



