61 
The larva derives its name of looper from its habit of "looping" 
in walking, due to the absence of legs on the sixth and seventh seg- 
ments. It is from the first a pale-green, fragile-looking creature. 
It varies considerably in color when mature; a large proportion of 
specimens that have come under observation are darker green than 
normal, and these are usually rather more strongly marked with the 
white lines shown in figure 
13 at c. Upon attaining full 
maturity the longitudinal 
white lines frequently disap- 
pear. In some individuals 
also there are rounded spi- 
racular spots on the three 
thoracic segments. 
An immature larva is 
shown in figure 11. 
The cocoon and pupa. — 
When the larva becomes full 
grown it constructs for 
pupation a remarkably fine, 
white, gauzy cocoon, which 
it usually attaches to the 
broad surface of a cabbage 
leaf or other plant on which 
it has fed. Strictly speak- 
ing, this is seldom a perfect 
cocoon, although some such 
can be found, as it uses the 
surface of the leaf for protection on one side and the gauze on the 
other. It seems probable that this is quite efficient against many of 
its enemies; and it is in the larval stage that the insect usuually suc- 
cumbs to the numerous natural enemies which will presently be men- 
tioned. The chrysalis varies somewhat in color, being rather pale for 
a Noctuid, the wing-pads moderate brown, and the abdominal seg- 
ments yellowish. The total length is a little less than three-fourths 
of an inch. It is shown in its cocoon at d (fig. 13). 
Fig. 13. — Plusia brassicse: a, male moth; b, egg shown 
from above in upper figure and from side in lower; 
c, full-grown larva in natural position feeding; (/, pupa 
in cocoon just before development of moth— a, c, d, 
about one-third larger than natural size; b, more en- 
larged (a, c, d, adapted from Howard; b, original). 
TECHNICAL DESCRIPTIONS OF THE STAGES OF THE LARVA. 
Stage I. — Head higher than wide, bilobed, mouth projecting, clypeus high, nearly 
reaching vertex. Antennse long; free from joint 2, somewhat flattened; luteous 
brown, the sutures of clypeus dark brown, area around mouth black, epistoma red- 
dish, antennae pale; width 0.25 mm . Body slender, moniliform, smooth. Whitish, 
translucent, pale green from the blood. Abdominal^eet on joints 9, 10, and 13. Cer- 
vical shield trapezoidal, black, small but distinct. Thoracic feet blackish, abdom- 
inal ones grayish outwardly, no distinct shields. Joint 12 enlarged. Tubercles 
