Tipula Tritici, and Ichneumon Tipule. 237 
the pollen or duft of the anthere, for in thofe florets in which it’ 
refides the germen never {wells, and the anthere are perfifting; 
from which it feems evident that the impregnation of the germen 
is prevented, either by the infeét’s ufing fome means, perhaps a 
kind of gluten, to prevent the pollen from burfting from the an- 
there, or, vice verfa, by doing fomething to the ftigma to prevent 
the fertilization of the germen. The pollen of three antherz 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 infeét, 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 bafe 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 clofer 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 confiderable, at leaft in this neighbourhood, when-you weigh 
the following refult of a particular examination of my own, which’ 
had this circumftance for its obje&. 
To afcertain the quantity of mifchief produced by our Tipufa: 
within particular limits, I went toa field of fifteen acres, which 
was planted partly with white and partly with red. wheat. _ In this. 
field I took five ftations, one on each fide, and one in the centre. 
In each ftation I examined a certain number of ears, grain by grain, 
without felection. The refult was, that in thirty ears of white wheat, 
feventy-three grains were deftroyed by the amy which is at the 
rate 
