148 
Observations on the various Insects 
In addition to what has been already said of the larvae, it may 
be added that the greater number 1 have seen were of a lemon or 
pale orange colour; they tapered to the head, which was pointed 
when they were in motion, and the tail was rounded, the sides being 
plaited or wrinkled, and forming little tubercles which assist it in 
locomotion (fig. 12 ; i, the same magnified) : the skin or membrane 
in which they were so often enclosed, although white and perfectly 
transparent, was of so close a texture that it was like a bubble of 
gum, and all that I examined were impressed with the transverse 
sutures corresponding exactly with the abdominal segments of the 
larvae (fig. 18, p), and it is worthy of remark that all these cases 
were fiactured at the head, as if an attempt had been made to 
escape, which was supported by the fact that their tails did not 
reach the apex of the case (fig. 18).* On taking out these larvae 
in January I found thetn dead, depressed, hardened, and granu- 
lated (fig. 19) ; they were composed of ten distinct and two less 
defined annulations, the penultimate one was notched beneath 
(fig. q), and the intestinal canal shone through on the underside. 
I have added a magnified figure from a drawing made for Sir 
Joseph Banks, and published in the ' Linngean Transactions ' (fig. 
13), f as it shows the papillae or nipples which assist the larva in 
walking, but it does not give the character of those which I have 
seen. J 
The Genus Cecidomyia is an extensive group containing nearly 
thirty British species,§ and one of the most remarkable features in 
their history is the great differences which exist in their economy : 
a large portion of them form downy excrescences, like galls, upon 
various plants, as the field wormwood, ground-ivy, a species of 
speedwell, and the common campion; others inhabit the leaves of 
the Scotch fir, the buds of a sallow, and the flower-buds of the 
common hedge-mustard ; and there are a few which Bouche says 
infest decayed tulip and hyacinth roots and half-decayed cow- 
dung. 
Mr. Kirby describes three minute parasitic insects which seem 
to have been ordained by the Author of the Universe to limit the 
dej)redations of the Wheat-midge, and they so effectually execute 
their mission, that it has often happened, a year or two after the 
Midges were in excess, not a specimen could be found. .As these 
insects are most interesting objects, as well for their valuable ser- 
* I find tfiat Mr. Gorrie has stated in the Magazine of Nat. Hist, for 
1829, that all the larvae had deserted the wheat-ears and descended into 
the earth by the 1st of August, about half an inch only below the surface. 
t Vol. in. pi. 22, fig. 12. 
% Professor Henslow is inclined to think, from differences in the larvae 
he has examined from various localities, that there is more than one species 
of wheat-midge. Vide his Report, vol. iii. p. 39. 
§ Curtis's Guide, genus 1149. 
