166 DISEASES OF THE COTTON PLANT. 
side of their bodies, and two broader ligbt-yellowish 
stripes along each side of their backs, down the centre of 
each of which was one distinct, narrow, hght-colored line. 
Each of the broader bands was marked with two black 
spots on each segment ; and on each segment of the sides 
were three or more dark dots. The head was yellowish- 
green, spotted with black. The caterpillars of the second 
and third generations are of a much darker color than 
those of the first ; their under parts are more of a yellowish- 
green, and their sides sometimes of a purple cast; their 
backs are black, with three distinct light-colored lines 
running down their length ; and their heads are also darker, 
and of a yellowish-brown, spotted with black. 
The question naturally arises, What causes this 
change of color in the latter part of the season, since the 
moths hatched from the lightest and darkest caterpillars 
prove to be exactly the same ? Several planters attribute 
it to the influence of the sun, or to the food upon which 
they subsist ; but this can scarcely be the case, as I have 
often observed individual caterpillars, evidently of the 
second or third generation, of the lightest green color, 
amongst a crowd of the black worms on the same leaf, as 
late as October, and exposed to the same influences of the 
sun. 
These insects appear to multiply to the greatest extent 
in damp, cloudy weather. When the older caterpillars are 
suddenly touched, they have the habit of doubling them- 
selves up and springing to a distance of several times their 
length ; but when imdisturbed, and not feeding, they appear 
to rest on the leaf with the fore part of the body elevated 
and somewhat curved, whereas, sometimes they keep up a 
species of swinging or jerking motion from side to side, 
as if enjoying the heat of the sun. 
