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62 General Notes. [ January, 
latter has been able to remove one or more of them, or that they 
dropped off from one cause or another. Eggs that have failed to 
hatch but that adhere to the worms are sometimes met with. 
The Aletia larvz attacked by this parasite are usually less than 
one-third grown, but not less than one day old. Exceptionally 
they are rather more than one-third grown. The eggs of the 
Euplectrus are usually laid on the middle of the back of the 
worm, sometimes a little more in front or behind or more towards 
the sides, and in one instance I saw them fastened immediately 
above one of the middle pair of thoracic legs. 
The delicate egg-shell splits longitudinally in the middle of the 
back and discloses the white larva of the parasite, which gradually 
works the egg shell more and more down the sides of its body 
where, for some hours, it remains visible as a black line, but with- 
in less than twelve hours it disappears from view beneath the 
rapidly growing parasite larva. This last, as soon as it has freed 
its head from the egg shell, pierces the skin of its victim and 
thereafter remains stationary with its head buried. As soon as it 
has fairly begun to feed, the white color changes toa bright bluish- 
green, and the segments and spiracles which in the newly hatched 
larva were barely visible under high magnifying power, are now 
readily seen. The growth of the larva is very rapid, but seems 
to vary according to the season, averaging three days in August 
and four days in September. When full-grown the larve crowd 
each other, and if there are five or more of them on a caterpillar, 
they form a semi-globular lump of very striking appearance. 
Usually their growth is uniform, and retardation in development 
of individuals in the group results in death. When full-grown 
they turn yellowish-white and relax their hold. 
The worm which up to this time showed no signs of being 
affected, except by its sickly yellowish color, and by its very slow 
growth, collapses and dies as soon as a single one of the parasitic 
larve withdraws, and the same fate overtakes those Euplectrus 
larve which are at the time less advanced in their development, 
or immature. If one of the parasitic larvae be removed by hand, 
both the victimized worm and the remaining parasites quickly 
dry up. 
The presumption that the Euplectrus larvae may migrate from 
one worm to another is unfounded, they always remain stationary 
on the worm, which the parent fly has chosen as its victim, and 
they never even move from the spot where the egg has been laid 
until they are full grown. Every attempt ! made to transplant 
a larva from one worm to another invariably resulted in the death 
of the parasite. 
In preparing for pupation, the larvae manage by a peculiar 
-.elongation and sudden contraction of their abdominal joints to 
work from the back of the worm to the ventral or attached side — 
where they spin fine silken threads, which more fully secure the 
