164 ZOOLOGY. 



brown to black. ' Male wingless. Female with small 

 wings bending outwards at their tips (Fig. 109) ; fore 

 wings horny, hind wings membranous. Larva orange 

 yellow ; head, prothorax, and tip of the abdomen, 

 black. After the last moult it becomes yellowish 

 white, and acquires scale-like wings. Hybernates in 

 the adult condition ; lays its eggs on various grasses, 

 also on different grain plants. The larvae, and, later 

 on, the perfect insects are found in large numbers 

 sucking the ovaries of flowering corn (wheat, rye, 

 barley) ; as a result of which the ears do not fully 

 develop, but wither away. Remedy : Deep ploughing 

 of the stubble, by which the hybernating individuals 

 are destroyed. 



The Elder Thrips (Thrips saTnbuci) lives in elder, 

 and sometimes also multiplies in very young field 

 beans, the leaves of which blacken and shrivel up in 

 consequence. 



The Flax Thrips (Thrips lini) often injures flax. 



Eighth Order : Diptera (Flies). 



Mouth parts elongated, adapted for sucking or 

 piercing. Fore wings developed, rarely absent. Hind 

 wings absent, as such, — altered into club-like bodies 

 (balancers or halteres) often covered with scales. 

 Metamorphosis complete. Larvae always legless ; most 

 have biting mouth parts and no distinct head (maggots) ; 

 the head-bearing dipterous larvae possess similar mouth 

 parts. The last become obtectate pupre (p. 93), while 

 the headless larvae become pupae within the larval skin. 



Family: Calicinse (Gnats). 



Slenderly built, with long, thin legs. An elongated 

 piercing proboscis in the female. The male with 

 feebly developed mouth parts, and feather-like antennae. 

 Both sexes suck up water and plant juices, and the 

 female blood as well ; hence only the latter bites, 

 especially at night. They hybernate in the adult 



