affectinff the Corn- Crops. 
149 
vices as for their curious habits of life, I shall enter with pleasure 
upon their histories the first opportunity. 
Notwithstanding these valuable agents, we find the amount of 
damage very considerable, as will be shown by the result of Mr. 
Kirby's examination in the neighbourhood of Barham, in Suffolk. 
"To ascertain the quantity of mischief produced by one Tipula 
within particular limits, I went to a field of fifteen acres, which was 
planted partly with white and partly with red wheat. In this field 
I took five stations, one on each side and one in the centre. In 
each station I examined a certain n\imber of ears, grain by grain, 
without selection. The result was that in thirty ears of white 
wheat, seventy-three grains were destroyed by the larva, which is 
at the rate of not quite two and a half grains to an ear ; and in 
twenty ears of red wheat twenty-nine grains were destroyed, which 
is nearly at the rate of one and a half grains to an ear. Take the 
whole together, and the proportion will be about two grains in an 
ear, which I suppose may be about a twentieth part of the pro- 
duce, and would make a difference of at least five coomb in the 
crop in this field. The white wheat in this instance was most 
exposed to the attack of the insect, — whether this be generally the 
case, must be determined by future experiments upon a more ex- 
tensive scale. Least mischief seemed to be done on the south side 
of the north hedge ; but no part escaped wholly — not an ear I 
examined but what had sustained some injury. From this field 
that I have been speaking of I went to another, which was sown 
later in the autumn : in this I found scarcely any of the larva?."* 
Mr. Markwick, who in the first instance did not consider the 
wheat-midge did any serious mischief, subsequently became satisfied 
that Mr. Kirby's average of two grains in each ear was not too 
much to attribute to the operations of the larvae, for " he scarcely 
examined any ears in which there were not more than that injured." 
In the ears transmitted to Mr. Marsham, from two to six grains 
were inhabited by them, and their numbers exceeded those repre- 
sented in the plate (fig. 10), and in one or two he found what ap- 
peared to be a pupa. Mr. Gorrie estimated the loss in the late- 
sown wheats in Perthshire, in 1828, at one-third of the crop :t 
and the following statement, commimicated by Mr. P. Bell, of 
Mid Lioch, and dated June 24, 1830, clearly shows the apprehen- 
sions occasioned in Scotland by its successive appearance. In 
alluding to the wheat-crop he says, " I found dozens of the insect 
busily at work depositing their eggs among the soft chaff of the 
young ear. We are anxious that the present cold weather should 
continue for another ten days, to prevent the eggs from hatching 
until the wheat be sufficiently hardened, and beyond the state 
* Trans. Linn. Soc, vol. iv. p. 237. 
■\- Mag. Nat. Hist., vol. ii. pp. 292 and 324. 
