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a hole in the skin, and each maggot spins for itself a small white oval 
cocoon, one end of which is fastened to the skin of the worm, and the 
caterpillar appears as if covered with small oval white eggs. Eighty- 
four flies were obtained from one caterpillar by Say, and Fitch counted | 
cone hundred and twenty-four cocoons on another worm, so that these 
insects must destroy a great number of worms, The parasite, however, 
is said to be destroyed by another hymenopterous insect, (Pteromalus 
tabacum,) which deposits its eggs in the cocoons of the microgaster. 
Another species, forming an immense mass of loose woolly cocoons, is 
also said to kill the caterpillar of the potato-sphinx, and most probably 
Fig. 6. 
. 
attacks also that of the tobacco-worm in a similar manner. It is, there- 
fore, of great consequence when destroying the caterpillars by hand- 
picking to avoid crushing or injuring any caterpillars which appear to 
have either white floss or egg-like cases on their backs or sides, as these 
are the cocoons of a very useful insect, which, if left undisturbed, would 
produce multitudes of flies, which would destroy an immense number 
of these injurious worms. 
The hornets, and an orange-colored wasp, taken by Walsh for a 
Polistes, devour the caterpillar when young and small. The best rem- 
edy against these insects, however, is to poison the fly which produces 
either the potato or tomato worm, by dropping a mixture of “blue — 
stone” of the druggists, or crude black arsenic, into the flower of the 
Jamestown weed, or stramonium, in the evening, when the fly will come 
and insert its long proboscis into the flower, sip up the poisonous mix- 
ture, and die before depositing its eggs. ' 
A correspondent from Tennessee finds it advantageous to cultivate a 
few plants of the Jamestown weed among his tobacco, and then to- 
poison the blossoms, as they appear, with the above-mentioned liquid, 
every evening, and has thereby saved a great part of his crop uninjared. 
In Maryland some tobacco-growers utilize young turkeys by driving 
them into the tobacco-field, where they pick the worms from the leaves. 
Some planters also pay a small premium to children for the dead millers 
or flies, which are readily killed with a piece of shingle or board as they 
hover over the flowers in the evening twilight. 
