DIPTERA. 437 



gether, and by their attacks cause the stems to become warty, 

 notched, and crooked, and afterwards to perish. But the ac- 

 counts, given of this kind of insect by the Baron Kollar * and 

 others, do not entirely agree with the little that is known respect- 

 ing our insect. 



We have reason to believe, that the maggots of the barley-fly 

 remain in the straw during the winter, and that they take the 

 winged form in the spring, in season to lay their eggs on the 

 young barley. It is therefore important to prevent them from 

 completing their transformations. This may be done by burning 

 the stubble, which contains many of the insects, in the autumn ; 

 by destroying, in the same way, all the straw and refuse which is 

 unfit for fodder ; and by keeping the grain in close vessels over 

 one year, whereby the insects, which are disclosed from the 

 small heavy pieces of straw remaining unwinnowed from the 

 grain, will perish without an opportunity to escape. 



The wheat crops in England and Scotland often suffer se- 

 verely from the depredations of the maggots of a very small gnat, 

 called the wheat-fly, or the Cecidomyia Tritici of Mr. Kirby. 

 This insect seems to have been long known in England, as ap- 

 pears from the following extract from a letter, by Mr. Christo- 

 pher Gullet, written in 1771, and published in the "Philosophi- 

 cal Transactions " for 1772. " What the farmers call the yel- 

 lows in wheat, and which they consider as a kind of mildew, is, 

 in fact, occasioned by a small yellow fly, with blue wings, about 

 the size of a gnat. This blows in the ear of the corn, and pro- 

 duces a worm, almost invisible to the naked eye ; but, being seen 

 through a pocket microscope, it appears a large yellow maggot, 

 of the color and gloss of amber, and is so prolific that I distinctly 

 counted forty-one living yellow maggots in the husk of one single 

 grain of wheat, a number sufficient to eat up and destroy the 

 corn in a whole ear. One of those yellow flies laid at least eight 

 or ten eggs, of an oblong shape, on my thumb, only while carry- 

 ing by the wing across three or four ridges." In 1795, the his- 

 tory of this insect was investigated by Mr. Marsham,f and since 



* Treatise, p. 124. 



t " Transactions of the Linnean Society," Vol. III., p. 142, and Vol. IV., p. 224. 



