THE WHEAT-FLY. 



427 



appeared the most infected, arising, no doubt, from 

 the seed of that sown earlier obtaining too great a 

 degree of hardness, before the insects come out, to 

 be liable to be much hurt by them. 



The Rev. Mr. Kirby attended very closely to 

 these insects ; but it was some time before he was 

 able to discover the parent flies, and still longer 

 before he could find them in sufficient numbers to 

 allow him to make the necessary observations as to 

 their habits and economy. 



In the beginning of June 1798, however, he 

 chanced to walk through a corn-field in the evening, 

 and, to his great surprise, observed an innumerable 

 multitude of them flying about in every direction ; 

 and, for near a month afterwards, found them in 

 the greatest abundance. They were seldom seen 

 before seven o'clock 3 at eight the fields appeared 

 to swarm with them, at which hour they were all 

 busily engaged in laying their eggs ; and about nine 

 they generally disappeared. They were so ex- 

 tremely numerous that, if each of them were to 

 lay its eggs in a different floret, and these eggs 

 were permitted to produce larva?, more than half 

 the grain of the adjacent country would infallibly 

 be destroyed. Twelve have been observed at the 

 same moment laying their eggs in the same ear: 

 but among all these myriads not one male could be 

 discovered. During the day-time none of these 

 insects are to be seen, as they then continue lodged 

 in a state of repose upon the lower part of the 

 culm. Upon shaking the stalks, however, they will 

 fly about. 



