CECIDOMYID^. 375 



the wheat is coming up ; they lay their eggs for a period of 

 th:"ee weeks, and tlien entirely disappear. The maggots hatched 

 from these eggs talvc the flax-seed form in June and July, and 

 are thus found in the harvest time, most of them remaining on 

 the stubble. Most of the flies appear in the autumn, but others 

 remain iu the puparium until the following spring. By burn- 

 ing the stubble in the fall, their attacks may best be prevented. 

 Among the parasites on this species, are the egg-parasites, 

 Platygaster, and Semiotellus (Ceraphi'on) destructor Say (Fig. 

 140), the latter of which pierces 

 the larva thi'ough the sheath of the 

 leaf. Two other Ichneumon para- 

 sites, according to Herrick, destroy 

 the fly while in the flax-seed or 

 semipupa state. The ravages of the 

 Hessian-fly have been greatly 

 checked bj' these minute insects, so 

 that it is in many localities not so 

 destructive as it was formerly. Dr. 

 Fitch has suggested that the Euro- 

 pean parasites of this insect and the C. tritici, could be im- 

 ported and bred in large quantities, so as to stop their ravages. 

 With proper pecuniary aid from the State this seems feasible, 

 while our native parasites might perhaps also be bred and 

 multiplied so as to effectuall}' exterminate these pests. 



The Wheat-midge, Diplosis tritici, attacks the wheat iu the 

 ear. When the wheat is in blossom the females lay their eggs 

 in the evening by means of the long retractile tube-like extrem- 

 ity of the bod}', within the chafly scales of the flowers, iu 

 clusters of from two to fifteen or more. In eight or ten days 

 the eggs disclose the transparent maggots, which with age be- 

 come orange colored, and when fully gi'own are one-eighth of an 

 inch long. The}' crowd around the germ of the wheat, which 

 by pressm-e becomes slu'ivelled and aborted. At the end of 

 July and in the beginning of August the maggots become 

 full fed, and in a few days moult their skins, leaving the old 

 larva skin entire, except a little rent in one end of it. "Great 

 numbers of these skins are found in the wheat ears immediately 

 after the moulting process is completed." Sometimes the 



