INSECTS. 
77 
THE GRASS CATERPILLAR. 
Another insect, (PI. VI. fig. 6,) which is often found in cotton- 
fields, and mistaken for the real cotton-caterpillar, is commonly 
known by the trivial name of the “ grass-worm,” or “ caterpillar,” 
owing to the circumstance of its most natural food consisting of grass 
and weeds, although, when pressed by hunger, it will sometimes eat 
the leaf of the cotton-plant. _ . . . 
These caterpillars were very numerous in the vicinity oi Colum- 
bus, in Georgia, about the end of September and the beginning 
of October, 1854. They devoured grass, young grain, and al- 
most every green thing which came in their path. Instances have 
been known in which, urged as they were by necessity and starvation, 
they actually devoured stacks of fodder that were stored away for 
winter consumption. Deep ditches cut in the earth to stop them 
were immediately filled up by the multitudes which fell in and per- 
ished, while eager millions still rushed over the trembling and half- 
living bridge, formed by the bodies of their late companions, bent on 
their mission of destruction and devastation. 
These caterpillars do no essential injury to the cotton, especially 
when weeds abound, as they content themselves with the grass grow- 
ing between the rows ; and, unless very numerous, they cannot be 
classed among those doing much harm to the general crop, and are 
mentioned here principally as having been so frequently mistaken for 
the real cotton-caterpillar. When pressed by necessity, however, as 
has already been stated, they will feed upon cotton leaves. I raised 
about thirty of them upon this food alone, merely as an experiment, 
and they grew and perfected their transformations, although appear- 
ing to prefer a grass diet if it could be obtained. When about to 
change, they formed cocoons of silk under stones or in the ground 
near the surface, interwoven with particles of earth, and came out 
perfect moths from the 24th to the 30th of October ; and, as these 
specimens were kept in a room without artificial heat, I conjectuied 
that those in the open fields would appear about the same time. 
At a plantation in the vicinity of Columbus, where the cater- 
pillars were very numerous, and had already devoured all the grass 
on one side of a field, which was divided into two equal parts by 
a broad and sandy carriage-road passing through the centre of it, 
the grass on the other side having been untouched, it was interest- 
ing to observe the operations of numerous colonies of ants that had 
formed their holes or nests in the road, and were lying in wait for 
any unfortunate grass-worm, the natural desire ol which for a iresh 
supply of food, should tempt it to cross this dangerous path. First, 
one ant more vigilant than the rest would rush to the attack ; then 
another, and another, until the poor caterpillar, entirely covered by 
its pigmy foes, and completely exhausted in strength by its unavail- 
