Tlpula Tritici, and Ichneumon 'Tipula. 2.3 j 



the pollen or duft of the anthers, for in thofe florets in which it 

 refides the germen never fwells, and the antherae are perfifting ; 

 from which it feems evident that the impregnation of the germen 

 is prevented, either by the infect's ufing fome means, perhaps a 

 kind of gluten, to prevent the pollen from burfting from the an- 

 thers, or, vicever/a, by doing fomething to the ftigma to prevent 

 the fertilization of the germen. The pollen of three anthers is a 

 ftore which will maintain fometimes thirty of thefe creatures, from 

 the time that the wheat is in bloffom, until it is nearly if not alto- 

 gether ripe. I could never difcover that the grain was injured in 

 any other way by this infect, but it invariably produces the inani- 

 tion of it in the floret which it inhabits. It may always be de- 

 tected by the difcoloured appearance of the bale of the corolla, 

 which is its ufual ftation. 



Although Mr. Markwick could not difcover any damage done to 

 the wheat in the year 1795, yet, upon a cloier examination in the 

 prefent year, that gentleman feems convinced that the inanition of 

 the grain takes place wherever the larva makes its attack, as appears 

 by his letter above quoted. My own obfervations fully confirm 

 this opinion ; and the mifchief occafioned by it will appear to you 

 very confiderahle, at lean; in this neighbourhood, when you weigh 

 the following refult of a particular examination of my own, which 

 had this circumftance for its objea. 



To afcertain the quantity of mifchief produced by our Ttfula 

 within particular limits, I went to a field of fifteen acres, which 

 was planted partly with white and partly Avith red wheat. In this 

 field I took five {rations, one on each fide, and one in the centre. 

 In each ftation I examined a certain number of ears, grain by grain, 

 without feleclion. The refult was, that in thirty ears of white wheat, 

 feventy-three grains were deftroyed by the larva, which is at the 



rate 



