16 
[ 276 ] 
mon over the whole. Upon opening the cocoons, I found, with 
very few exceptions, not pupce, but partly changed caterpillars, 
dead and dry, and in each of these two or three, and sometimes 
four coarctate pupae, of a regular oval form and mahogany color, 
evidently belonging to some parasitic two-winged fly. In some 
were found the larvae or maggots, not yet changed to pupae. 
They are from three to four-tenths of an inch in length, and present the ordinary 
characters of the larvae of the Muscidae or fly family. The body is somewhat tapering, 
anteriorly, and capable of considerable extension. The only parts of the mouth visible 
are two minute, curved, black mandibles or teeth. The body is rounded, posteriorly, 
with a shallow depression, in which are situated two conspicuous spiracles or breathing 
pores. On all the rings, but mostly on those nearest the extremities, are numerous mi¬ 
croscopically minute, black, spinous points. These points extend all around the body, 
beneath, as well as above, and probably assist the larvae in the slight locomotion which 
it requires. The pupa is a quarter of an inch long, with slight, but distinct segmental 
incisions, and even with vestiges of the spinous points of the larva, proving that the 
covering or case of what are known as coarctate pupae is really only the skin of the 
larva contracted and hardened. 
The parasitic flies began to emerge from their pupal cases during the first week of 
September, and proved to belong to the genus Tachina, proper, as restricted by Mac- 
quart, and to section AAA, distinguished by having the third joint of the antennae a 
little more than twice the length of the second. They resemble the common house-fly, 
but are somewhat larger and have more bristly bodies. Many of the Tachince bear a 
close resemblance to each other, and are therefore difficult to distinguish from each 
other by merely verbal descriptions. This species maybe appropriately named the Tach¬ 
ina orgyice. Length about one-third of an inch; sides of front, pale golden; middle 
space, velvet black; face, silver-ash; fascial bristles, reaching nearly to the middle of 
the face; eyes, bare; third joint of antennae, a little more than twice as long as the sec¬ 
ond; second joint of the seta, well developed; third joint of seta, thickened for half its 
length; palpi, brownish; thorax, with alternate stripes of black and dusky cinereous. 
First longitudinal vein of the wings, after* the auxiliary, reaching the middle of the 
costa. Third and fourth veins, almost meeting, some way before the tip of the wing. 
Fourth vein, prolonged beyond the curve, half way to the border. Discal cross vein re¬ 
moved its own length from the border, and more than half its length from the flexure 
of the fourth vein. Abdomen black with cinereous reflections at the incisions and on 
the basal half of the segments, except the first. Two bristles on the hind margin of 
the first and second segments. Terminal segments many bristled. 
Of the myriads of cocoons here accumulated, it appeared that 
scarcely one out of a hundred had escaped the fatal visitation of 
these parasites. So that the race of caterpillars, so abundant and 
destructive this year, may be considered as practically extermi¬ 
nated in this locality. 
It might seem, at first sight, that a knowledge of parasitic in¬ 
sects is of no practical importance, inasmuch as they carry on their 
beneficent work wholly irrespective of our cognizance or co-ope- 
