INSECTA. 



251 



I 



K The "piercing and sucking" mouth parts are well shown 

 nn the gad-fly {Tabanus). The upper lip {labrum) mandibles 

 and maxillae are lengthened and produced into sharp stylets, 

 whilst the labium is produced into a long hairy proboscis 

 with two terminal lobes. In gnats the " piercing " stylets 

 ; are best developed, whilst in flies, such as the house-fly, the 

 * sucking " proboscis is large and the stylets are small. 



Fig. 171. — Wheat Midge [Cecido/nya tritici). 



A, Larva in wheat-flower ; B, larva in grain ; C, larva ; D, fly. 



