FIELD BOOK OF INSECTS. 



ITONIDID^E (OR CECIDOMYIID^E) 



The layman usually knows these only by their works. 

 Many of them are gall makers (see p. 457) or live in galls 

 made by other species; some breed in decaying wood and 

 bulbs, others under bark and in fungi, while still others 

 feed on plant lice. Unlike most Diptera, many of these 

 pupas are enclosed in a cocoon formed by an exudation 

 from the larvae. The genus Miastor contains species 

 whose larvae sometimes develop eggs which hatch, without 

 fertilization, inside their "mothers," the children then 

 devouring their parent. 



"Probably no other insect does so wide- 



Mayetiola spread damage as the Hessian Fly, attacking 



destructor 



our chief staple, wheat, as well as rye and 



barley. One-tenth of the whole crop, valued at $50,000,- 

 ooo to $70,000,000, is generally conceded to be destroyed 

 by this pest ev,ery year. In certain sections the loss often 

 amounts to from 30 to 50 per cent., and in 1900 was esti- 

 mated at fully $100,000,000" (Sanderson). It (Plate 

 LXV) is a European insect which was first noticed on 

 Long Island shortly after the Hessian troops landed 

 there. The adults are dark-colored gnats, about .1 in. 

 long. The larvas imbed themselves in the plant, especially 

 where the stem is covered by a leaf, absorb the sap, and 

 weaken the straw. The "flax-seed" is the puparium. 



The Wheat-midge, Diplosis tritici, was introduced from 

 Europe a few years after the Hessian Fly. Its larvae 

 feed on the developing wheat-heads and pupate in under- 

 ground cocoons. The larvae of Dasyneura leguminicola 

 feed on clover seed. The Pear Midge, Contarinia pyrivora, 

 is another immigrant from Europe; it causes a lumpy 

 growth in the fruit, the larvae working chiefly at the core. 



MYCETOPHILID^E 



The larvae of these minute Fungus Gnats feed on fungus 

 (including cultivated mushrooms) and decaying vegetation, 

 often living in the soil of potted plants. Many, especially 

 species of Sciara, are gregarious and travel in "armies" 



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