470 INSECTS INJURIOUS TO VEGETATION. 



humiliated by the reflection, that the Author of the universe 

 should have made even small and feeble insects the instru- 

 ments of His power, and that He should occasionally permit 

 them to become the scourges of our race, ought we not to 

 admire His wisdom in the formation of the still more humble 

 agents that are appointed to arrest the work of destruction. 



The wheat crops in England and Scotland often suffer 

 severely 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 Eng- 

 land, as appears from the following extract from a letter, by 

 Mr. Christopher Gullet, written in 1771, and published in the 

 "Philosophical Transactions" for 1772. " What the farmers 

 call the yellows 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 produces 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 am- 

 ber, 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 carrying by the 

 wing across three or four ridges." In 1795, the history of this 

 insect was investigated by IVIr. Marsham,* and since that time 

 Mr. Kirby ,f Mr. Gorrie, and Mr. ShirrefF, J have also turned 

 their attention to it. The investigations of these gentlemen 

 have become very interesting to us, on account of the recent 

 appearance, in our own country, and the extensive ravages, of 

 an insect apparently identical with the European wheat-fly. 

 The following account of the latter will serve to show how far 

 the European and American wheat-flies agree in their essential 



* " Transactions of the Linnaean Society," Vol. III., p. 142, and Vol. IV., p. 

 224. 



t "Transactions of the Linnaean Society," Vol. IV., p. 230, and Vol. V., p. 96. 

 J Loudon's "Magazine of Natural History," Vol. II., p. 323, and 448. 



