State Agricultural Society. 
913 
HABITS OF THE FLIES AND THEIR LARVAE* 
lepidse, and the powerful Sand-wasps being all parasitical animals, 
which by depositing their eggs in the bodies or upon the skins of 
the larvae of noxious insects, keep them within certain limits; 
otherwise it is doubtful whether any crop would reward our toils. 
Such, however, is not the character of the Saw-flies, or Tcnthredos 
as they are termed by Linnaeus; for there are few insects that 
prove more fatal, when favored by congenial seasons. It is only a 
few years since whole districts of turnips were completely con¬ 
sumed by Abhalia spinarum. Our beautiful Rose-trees are subject 
to the attacks of five different species, and amongst them Itylotoma 
Rosce which skeletonizes the leaves; then our Plum, Cherry and 
Pear trees have the upper cuticle and parenchyma so completely 
rubbed off by the shiny, slug-like larvai of Tenthredo Ccrasi, that 
the crops, especially of Pears, are often materially injured. Our 
Raspberry bushes also are subject to the invasion of another spe¬ 
cies; and the extensive devastations of the Gooseberry Saw-fly are 
fresh in the memory of every cultivator.” 
After describing the fly, he says, “The flies emerge unheeded 
from their tombs the beginning of April, and the female soon 
deposits her eggs close to the sides of the principal nervures on 
the underside of the leaves, which is very remarkable, for all the 
females of this extensive family are furnished with an instrument 
called the saw, for the purpose of cutting into the leaves and stalks, 
and introducing the eggs between the cuticles or under the bark.” 
Although it may be “very remarkable” that these flies do not 
employ their saws for sinking their eggs into the texture of the 
leaves, it is by no means unusual, our Rose Saw-fly and several 
other species merely dropping or very slightly gluing their eggs 
to the surface of the leaves. 
“ In about a week the larva; hatch, and commence feeding on the 
leaves on which they are stationed, and soon riddle them full of 
small holes; thus they go on, feeding and changing their succes¬ 
sive skins as they increase in size, until they are three-fourths of an 
inch long, when they are seen scattered around the edges of a 
partly demolished leaf, holding by their fore legs, with their tails 
turned up, or tying on one side. 
“There seems to be a succession of broods, from the early spring 
until October occasionally; but the greatest numbers are congre¬ 
gated in May and the beginning of June, when, I understand 
they have caused twenty to thirty pounds of damage in a market 
IAg.i 58 
