Wheat Flies. 



291 



stems were seen no holes ; whence Bjercander conjectured that 

 the eggs, or larvae, must enter at the top of the leaves. The fly, 

 when hatched, forces its way upwards, and flies out of its former 

 abode. 



The dwarf stems were observed to grow yellow, and decay, on 

 the 14th of June; and were in such abundance, that, in some 

 fields, 8, 12, or 14, were found in a square of 2 ft. ; from which 

 the writer concludes that great injury is done to the rye, and 

 strongly recommends that the stems should be pulled up and 

 burned whilst the insect is in either the larva or pupa state; by 

 which means, he thinks, one or two persons might destroy many 

 thousands of them in a day ; he hin)self having picked up 350 

 stems in as few hours. 



Soon after this memoir was published, Mr. Mark wick read a 

 memoir before the Linnaean Society, upon the habits of a fly sup- 

 posed to be identical with the Miisca pumilionis, which, in the 

 course of the spring of 1791, had been observed in the neigh- 

 bourhood of Battle, where, in the early part of the spring, some 

 fields of wheat appeared to be much blighted; the injury being 

 caused by a small grub, lodged in the centre, or very heart, of the 

 stem, just above the root. At the end of March, the insect was 

 generally in the larva state ; but in some it was already changed 

 to a chrysalis. This memoir was published in vol. ii. of the 

 Transactions of the Linncean Society^ accompanied by a plate, 



from which onv Jigs. 102. b c, 103., and 101. f g, are copied. 

 Fig. 102. b represents a young wheat plant, with the centre 



u 2 



