THE AMERICAN CLOSTERA. 
481 
I have seen on the oak, the birch, the black walnut, and 
the hickory trees, swarms of caterpillars slightly differing in 
color from each other, and from those above described, that 
live on the apple and cherry trees ; they were more hairy 
than the latter, but their postures and habits appeared to be 
the same. Whether they were all different species, or only 
varieties of the ministra^ arising from difference of food, I 
have not been able to ascertain. 
The cultivation of the balsam and our other large-leaved 
native poplars seems to have been neglected of late years. 
It is true that these trees are not so durable and so valuable 
as many others; but we sometimes meet with noble speci¬ 
mens of them ; and the rapidity of their growth, the great 
size they attain in favorable situations, and the fine shade 
they afford, are qualities not to be overlooked or despised ; 
nor is the wood entirely worthless, either as fuel or in the 
arts. If these trees are planted alternately with other more 
slow-growing trees, we shall have the benefit of the shade 
and shelter of the former till the others have become larfie 
enough to fill their places. They are not subject to be 
attacked by canker-worms, oak-caterpillars, web-worms, and 
many other kinds of insects that infest our ornamental and 
shade trees of hard wood; but, unfortunately, they suffer 
too often from insect depredators of their own, such as 
the grubs of two or three kinds of beetles, which bore 
into their trunks ; the spiny caterpillars of the Antiopa 
butterfly and of the lo moth, the fork-tailed Cerura, the 
caterpillar of the herald-moth, and another kind of cater¬ 
pillar now to be described, all which devour the leaves 
of these trees. This last kind of cat- 
ei'pillar (Fig. 213) is found in little 
swarms on the trees from the last of 
July to the beginning of October. It 
does not raise the hinder part of its body when at rest. 
It is nearly cylindrical, with two little black warts close to¬ 
gether on the top of the fourth and' of the eievehth rings. 
