Tlie Progress of the Hessian Fly. 
439 
Mr. Taylor, of Errol, who was fortunate enough to be able to 
watch a female deposit eggs upon a wheat-plant under glass. 
Mr. Taylor gives the following description of this : — " The fly 
goes about egg-laying in a business-like manner, with its head 
towards the point of the blade and the ovipositor extended in a 
kind of semi-circle to reach the conical surface of the blade. 
After it has laid one egg it takes a flight round the blade and 
alights again at almost the same place to repeat the operation, 
until a row of verv minute specks of a vermilion colour is laid 
along the centre of the blade. I could not say that it laid more 
than two eggs at a time, without a change of position, nor how 
many it laid. ' This corresponds with the account of oviposition 
in America, given bv Professor Cook as quoted bv Dr. Packard, 
and by Professor Rilev. Dr. Lindeman's story of the egg- 
laying in Russia is much the same as that told in England and 
America. He savs, however, that the eggs are glued together 
by a sticky substance and laid in little heaps of five to eight on 
the leaf. Each female lays 230 eggs, according to Dr. Lindeman, 
who calculates that, allowing a proportion of half as males, one 
female in a year would be the progenitrix of 30,180,750 indi- 
viduals.* 
Xo observations have been made with regard to the larvae 
of the autumn generation. These have not been discovered 
upon the wheat plants in the autumn. Larvae were found by 
Mr. Palmer upon barley-plants in the first week in July, to- 
gether with pupa-cases. These resembled the descriptions of 
entomologists of the larva? of the Hessian Flv in America, as 
well as those in Russia given bv Dr. Lindeman ; though it 
should be noticed that Dr. Lindeman states that the larva has 
ten pairs of spiracles, and Professor Rilev, writing of the 
American larva, avers that it has nine pairs. The larvae seen 
by myself were just on the point of changing into pupae, but 
their identity was unmistakable. 
Dr. Lindeman has given a most interesting: account of the 
larva, as seen by him in Russia, with more details as to this 
state than have been noted previously. The mouth is described 
as a tiny cut, or rent, on the under surface of the head-segment. 
Round the mouth there are chitinous coverings, plates of mail. 
It is also lurnished with an instrument evidently adapted lor 
boring holes in the tissues of the corn-stems. 
'■^s to the injury caused by the larvae, whose term of active 
injurious existence is not more than from 30 to 33 days, it 
seems disproportionate, and cannot be solely from their absorp- 
tion of the sap of the plants. For instance, there mav only be 
Op. cU, 
