REMEDIAL AGENCIES. 
Fortunately for our farmers nature has provided a number of 
natural enemies to the Army-worm, that assist very materially in keep¬ 
ing it in check. 
Natural Agencies. 
The most important of these are the insect parasites which attack the 
worms in great numbers when they appear in marching armies. In 
fact, so rapidly are these parasites developed, that in the great 
Army-worm years, as a general rule, two-thirds or more of the worms 
collected for study are found to be parasitized; such at least was 
the case with those collected by Prof. Riley in 1869. There are sev¬ 
eral species of these parasites, some of which are dipterous insects, 
others hymenopterous. 
The Red-tailed Tachina Fly— (Nemoreea leucanue.) Kirk. 
This is a true two-winged fly, resembling in form and size the 
common house-fly, or more closely the blow-fly or flesh-fly, but may 
be distinguished from these by the color, black and gray with a 
satiny lustre on the hinder part of the body, and the last segment 
of the abdomen dull red. It differs from the common fly in having 
the bristles of the antennae simple or naked and not feathered; and 
by other characters mentioned in the description which we give be¬ 
low. 
As nature has not furnished it with a piercer at the end of the 
tail, as are the hymenopterous parasites, with which to pierce the body 
of its victim and deposit its eggs within, it must of necessity place 
them on the outside of the worm. 
The place selected is the back of the first three or thoracic seg¬ 
ments, a spot which instinct probably leads it to know the worm 
is unable to reach with its jaws. Here they are firmly glued to the 
skin by a kind of liquid cement secreted by the fly, wdiich soon 
hardens, and which, as it is insoluble in water, prevents them from 
being washed off by the rain. So firmly, in fact, do they become 
attached, that it is impossible to remove them without destroying 
them. They hatch out about the time the worm reaches its full 
growth and hides away to enter the pupa state and undergo its trans¬ 
formations. Soon after their exit the maggots work their way into the 
body of their host, just when and how is not positively known, but 
evidently just about the time the caterpillar settles into position to 
pupate. Mr. Walsh says, “they uniformly devoured the larva before 
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