THE AMERICAN CLOSTERA. 431 



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 large 

 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- 

 erpillar (Fig. 213) is found in little Fig> 

 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 eleventh rings. 



