165 
size; it then goes into the earth and the pupa (Fig. 4) is formed in-a 
subterranean cell, the late broods remaining as pupz all winter, and 
coming out as the perfect fly the Fie 4 
following spring. The insect (Fig. “ 
5) appears from June and July until 
late fall. It hovers in the twilight ¢ 
like a humming-bird over flowers, 4. 
especially honeysuckle and James- = Sy 
town weed, Datura stramonium, a 
sucking the nectar by means of its long, flexible tongue, which, when 
the insect is at rest, is coiled up like a watch-spring under the head. 
The tongue when unrolled measures four to six inches in length, and 
the caterpillar feeds also on the potato, red pepper, avd tomato, as 
well as the tobacco. This insect is almost exactly like the northern 
so-called potato-worm in all the states of larva, pupa, and insect, and 
can scarcely be distinguished from it by young entomologists; but in 
the “tobacco-worm” the anal horn on the tail of the caterpillar is red- 
dish instead of bluish; it also has no longitudinal white stripe, the 
pectoral feet are ringed with black, the body is more hirsute, and the 
insect itself is more indistinctly marked, and always hasa white mark 
at the base of its wings and partly on the thorax, (Fig. 5) which the 
moth of the potato-worm has not. (Fig. 6.) 
Fig. 5. 
The potato-worm is also found feeding on the tobacco in Maryland, 
and frequently a black or nearly black variety of the worm is taken, 
especially towards the end of the season. The potato or tomato worm 
has also been accused of being poisonous, but this is entirely erroneous, 
as the horn on the tail of the caterpillar is incapable of inflicting any 
serious wound, and has no poisonous properties whatever. The potato- 
worm is the: northern species, and in Maryland the two species meet, 
and are found indiscriminately together in the tobacco-fields, yet never 
mixing, but remaining perfectly distinct, although so nearly allied in 
appearance, habits, and food. 
There are several parasites, and one in particular, that is very useful 
in destroying the potato and tobacco worm. It is a minute, four-winged 
fly, (Microgaster congregata,) which deposits its eggs in the caterpillar, 
and eventually kills it. The eggs of this parasite, to the number of 
one hundred or more, are deposited in the back and sides of the cater- 
pillar, in small punctures made by the ovipositor of the fly. The larva, 
when ee: teed upon the fatty substance, and when fully grown eat 
A 
