DIPTERA. 439 



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 depreda- 

 tions, 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 pupa;, within the ears of the wheat, and from these they ob- 

 tained 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 oval form, tapering at each end. 

 The pupse found in the ears were very few in number, scarcely 

 one to fifty of the maggots. Hence Mr. Kirby supposes, that 

 the latter are not ordinarily transformed to flies before the spring. 

 Towards the end of September he carefully took off the skin of 

 one of them, and found that the insect within still retained the 

 maggot form, and conjectures that the pupa is not usually com- 

 plete until the following spring. According to Mr. Gorrie, the 

 maggots quit the ears of the wheat by the first of August, descend 

 to the ground, and go into it to the depth of half an inch. That 

 they remain here unchanged through the winter, and finish their 

 transformations, and come out of the ground in the winged form, 

 in the spring, when the wheat is about to blossom, is rendered 

 probable from the great number of the flies found by Mr. Shir- 

 reff, in the month of June, in all the fields where wheat had been 

 raised the year before. The increase of these flies is somewhat 

 checked by the attacks of three different parasites, which have 

 been described by Mr. Kirby. 



An insect, resembling the foregoing in its destructive habits, 

 and known, in its maggot form, by the name of " the grain- 

 worm," has been observed, for several years, in the northern 

 and eastern parts of the United States, and in Canada. It seems 

 by some to have been mistaken for the grain-weevil, the Angou- 

 mois grain-moth, and the Hessian fly ; and its history has been 

 so confounded with that of another insect, also called the grain- 

 worm, in some parts of the country, that it is difficult to ascer- 



