216 HIGH SCHOOL ZOOLOGY. 



To tlie Diptera belong the moscjuitos {C'uUcidie), black-flies 

 (Simulidce), and horse-flies (Tahariidce), the females of which 

 suck blood tlu'ough wounds made by their piercing stylets. 

 The larvse are aquatic, or, as in the case of the horse-flies, they 

 live in the earth. Thei^e are also forms like the Hessian-fly 

 ^ {Cecidomyia destructor), wliich are injurious to cultivated 

 phxnts, eggs being deposited within the cellular tissue, and thus 

 forming galls, in which the larvre are developed. Again, there 

 are the domestic flies {Muscidce), in which the ends of the 

 labium — (labellce) — are converted into a rasping proboscis, which 

 enables them to dispense with their piercing stylets. The 

 larvse (maggots) lead a parasitic or saprophytic life. Finally, the 

 fleas (Pulicidce) are distinguished by the absence of wings and 

 Ijy the serration of their mandibles, which adapts them better 

 for their life of semi-parasitism. 



Many diSerences of habit are likewise met with among the 

 Lepidoptera. Small forms like the clothes-moths (Tinea) belong 

 to the Microle2ndo2)tera, which also include a host of forms de- 

 structive to vegetation, in one way or anothei*, like the coddling- 

 moth {(J arpocapsci). Such is also the case among the larger 

 forms, Macroleindo'ptera, which include the butterflies {Papil- 

 ionid(e), hawk-moths {Sphingidce), silk-worm moths (Bomhy- 

 cidce), and other families. 



It is in this order that remarkable instances of protective resemblance 

 to other animals (so-called mimicry) was first observed. The bee-moths 

 (e. g., Sesia tlujshe and others) receive their names from (and owe their 

 freedom from attack to) their resemblance to various stinging wasps. 



34. The most highly developed of all insects are undoubtedly 

 the Hymenoptera. They exhibit this in the reduction of the num- 

 ber of the abdominal segments and in the concentration of the 

 nervous system, as well as in the social life which characterizes 

 the higher genera. It is possible to recognize in the parts of 

 the mouth, all of those met with in the locust, but the charac- 

 teristic " tongue" of the bee is formed by the fusion and jii-olong- 



