790 
Joumal of Agricultural Research v 0 i. xxx, No. s 
plant, feeding in groups on the latter 
tissue, which lines the hollow stem. 
The larvae cover their entrances 
through which they pass into the stalk 
with tympana of siik. Later the moths 
rupture these structures as they emerge 
from the stalk. When full grown, the 
larva spins a pad of silk against the in¬ 
side wall of the stem, in which one finds 
the cremaster of the pupa securely fas¬ 
tened, thus suspending the larval head 
downward. In 1921, under insectary 
condil ions, the insect remained as a 
pupa 12.7 days. The moths appeared 
in mid-July and continued to emerge 
into August. 
Full-grown larvae are slightly smaller 
than the larvae of Pyrausta nubilalis, to 
which they bear resemblance. The 
black head, thoracic shield, and pinac- 
ula of the body segment sharply con¬ 
trast with the yellowisli-white integu¬ 
ment of the larva. The anal shield is 
lemon yellow. The dorsal surface is 
granulated, but the skin granulations 
are never as dense as in the larvae of 
Pyrausta. The prespiraeular pinacula 
bear three setae, the chitinous rings of 
the spiracles are stout and black, the 
crochets on the planta of the pseudo¬ 
pods are in a completed circle, and the 
setal arrangement on the ninth ab¬ 
dominal segment differs from that of 
all the larvae previously discussed in 
this paper (pi. 2, D). 
FAMILY NOCTUIDAE 
HELIOTHIS OBSOLETA FAB. 
Bombyx obsoleta Fab., 1793, Ent. Svst., pt. 1 
3:456. 
Noctua armiger Hiibn., 1810, Samml. Eur. 
Schmett., Noct., 370. 
Heliothis armiger Hiibn., Dyar, 1902, List No. 
Amer. Lepidop., No. 2300. 
Chloridea armigera Hiibn., Hampson, 1903, Cat. 
Lepidop. Phal. Brit. Mus., 4:45. 
Heliothis obsoleta Fab., Barnes and McDun- 
nough, 1917, Check List Lepidop. Bor. 
Amer., No. 1090. 
Although the larva of the corn ear- 
worm (Heliothis obsoleta Fab.) primarily 
attacks the grain on the ear of field and 
sugar corn, it is also known to feed 
freely on the silk and sparingly on the 
foliage. The European corn borer at¬ 
tacks all parts of the plant. It habitu¬ 
ally lives within burrows made in the 
stalk, in the midrib of the leaf, on the 
ear, and in the cob. The corn ear worm 
never drills through the tough fibrous 
cortex of the corn plant or into the 
cob. When the insect attacks cotton, 
however, the larva bores into the boll, 
destroying the lint and the seeds. Both 
the corn borer and the earworm feed on 
the corn kernels, but the larva of the 
latter invariably enters at the tip end, 
whereas the corn borer enters the ear 
at every conceivable point, such as 
through the tip, through the side, and 
through the butt, and very frequently, 
indeed, it lives in the pith of the cob. 
Caffrey has noted that the breaking 
over of tassels in a cornfield does not 
necessarily preclude feeding in these 
parts by the corn borer, since he has 
found that the earworm is capable of 
occasionally doing the very same thing, 
particularly in late-developing sweet 
corn. The corn earworm is a most im¬ 
portant destructive pest. Estimates 
have been made of an annual loss of 
from 2 to 5 per cent of the total corn 
crop produced in the United States, or 
of $30,000,000 to $50,000,000. The 
insect occurs throughout the United 
States and in many parts of the world. 
In addition to the injury inflicted 
by the earworm to corn, it attacks 
such important crops as tobacco and 
cotton. Tomatoes, beans, forage 
plants, and many others are periodi¬ 
cally damaged. The caterpillars are 
large, robust forms belonging to the 
same family of insects as the cutworms. 
They are exceedingly variable in color, 
ranging from green to rose, brown to 
black, striped, spotted, or plain. Thus 
in a field one may collect larvae which 
to the layman or to the farmer would 
seem entirely different. When the 
larvae have completed their growth 
they fall or descend of their own ac¬ 
cord to the soil, burrow 2 to 5 inches 
into it, and construct cells wherein they 
pupate. The corn borer never enters 
the soil to pupate but transforms in its 
burrow or in another place of seclusion 
to which it has migrated. In the Gulf 
States there are four broods of the ear- 
worm annually, along the Gulf coast 
there may be five or six, whereas in the 
northern States there are two, with 
possibly only one in the province of 
Ontario, Canada. In Massachusetts in 
1921 the corn earworm was abundant 
and destructive. 
The larvae are larger than those of 
the European corn borer, measuring 
when fully grown 134 to 1J4 inches in 
length. The dorsal pinacula are small, 
pale, or blatk, depending on whether 
the larva is light or dark colored; the 
supraspiracular pinacula o;i the pleura 
are always black or deep brown. The 
crotchets on the prolegs are character¬ 
istically noctuid (pi. 2, M) in a meso- 
series. In the European corn borer, 
as pointed out elsewhere, the crochets 
are arranged in an incompleted circle 
with the opening outermost. The head 
capsule of the corn earworm is yellow- 
brown and mottled, whereas in the 
corn borer the head capsule is usually 
