THE EUROPEAN WHEAT-FLY. 589 



minute hairs; those of the male will probably be found to 

 have a greater number of joints. 



Towards the end of June, or when the wheat is in blos- 

 som, these flies appear in swarms in the wheat-fields during 

 the evening, at which time they are very active. The 

 females generally lay their eggs before nine o'clock at night, 

 thrusting them, by means of a long, retractile tube in the 

 end of their bodies, within the chafly scales of the flowers, 

 in clusters of from two to fifteen or more. By day they re- 

 main at rest on the stems and leaves of the plants, where 

 they are shaded from the heat of the sun. They continue 

 to appear and lay their eggs throughout a period of thirty- 

 nine days. The eggs are oblong, transparent, and of a pale 

 buff color, and hatch in eight or ten days after they are 

 laid. The young insects produced from them are little foot- 

 less maggots, tapering towards the head, and blunt at the 

 hinder extremity, with the rings of the body somewhat 

 wrinkled and bulging at the sides. They are at first per- 

 fectly transparent and colorless, but soon take a deep yel- 

 low or orange color. They do not travel from one floret to 

 another, but move in a wriggling manner, and by sudden 

 jerks of the body, when disturbed. As many as forty-seven 

 have been counted in a single floret. It is supposed that 

 they live at first upon the pollen, and thereby prevent the 

 fertilization of the grain. They are soon seen, however, 

 to crowd around the lower part of the germ, and there 

 appear to subsist on the matter destined to have formed the 

 grain. The latter, in consequence of their depredations, 

 becomes shrivelled and abortive ; and, in some seasons, a 

 considerable part of the crop is thereby rendered worthless. 

 The maggots, when fully grown, are nearly one eighth of 

 an inch long. Mr. Marsham and Mr. Kirby found some 

 of them changed to pupae within the ears of the wheat, and 

 from these they obtained the fly early in September. The 

 pupa represented by them is rather smaller than the full- 

 grown maggot, of a brownish yellow color, and of an oblong 



