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not uncommon, and generally fly near the ground, but their habits are otherwise 
unknown. I have taken them as far eastward as Nova Scotia, but I do not know 
how far westward their range extends. The male is exceedingly rare, and I have 
only seen one specimen that was captured in Ontario. 
Although this review of the great complex of insects embraced in the Para- 
sitica has been a very rapid and incomplete one, I hope that it has at least given 
some idea of their great number, their diversity of structure and their economic 
importance. We see that egg, larva and pupa are alike subject to their attacks, and 
that scarcely any form of insect defence appears to be sufficient to prevent their 
attacks. The grub gnawing his hidden burrow in the tree, and the scale insect 
adhering firmly to the twig, alike have their parasitic foes differing in size and 
method of attack. 
It will be observed further that the value of any species in destroying 
obnoxious forms does not depend upon its size or strength. The greatest benefits 
are often effected by atoms so minute as almost to escape our search, but which 
by their numbers work wholesale destruction to their victims. The tiny fly that 
destroys a cluster of eggs is a greater helper than the larger one that might later 
destroy the brood of caterpillars, because in the latter case a certain amount of 
depredation is committed before the labours of the parasite are fulfilled. The 
diminutive devourers of aphides are of unknown value, as plant-lice increase so 
enormously by rapidly succeeding generations that if it were not for such pro- 
vidential safeguards they would swarm everywhere working devastation. 
INSECTS INJURIOUS TO THE ELM. 
BY F. B. CAULFIELD, MONTREAL. 
First are insects injurious to the trunk. 
1. THE Common ELM-TREE Borer, Saperda tridentata, Oliv, Order Coleop 
tera, Family Cerambycidee.—aA very destructive insect, boring in the inner bark 
and the surface of the wood of elm trees. Fitch states that the eggs are deposited 
in June and that the young larvee nearly complete their growth before winter, 
and soon after warm weather arrives in spring they pass into the pupa state. 
Packard, who has found the larva in abundance in spring in Providence, under 
the bark of old dead elms, describes it as follows :—* White, snb-cylindrical, a 
little flattened, with the lateral fold of the body rather prominent; end of the 
body flattened, obtuse, and nearly as wide at the end as at the first abdominal 
ring. The head is one-half as wide as the first prothoracic ring, being rather 
large. The prothoracice segment, or that next to the head, is transversely oblong, 
being about twice as broad as long; there is a pale Worsal corneous transversely 
oblong shield, being about two-thirds as long as wide, and nearly as long as the 
four succeeding segments ; this is smooth, except on the posterior half, which is 
rough, with the front edge irregular and not extending far down the sides. Fine 
hairs arise from the front edge and sides of the plate, and similar hairs are 
scattered over the body and especially around the end. On the upper side of 
each segment is a transversely oblong ovate roughened area, with the front edge 
slightly convex, and behind slightly arcuate. On the under side of each segment 
are similar rough horny plates, but arcuate in front, with the hinder edge 
straight. 
