THE AILANTHUS SILKWORM — THE HOUSE-BUILDER MOTH. 301 



necessarily very great Although the thread is not so fine or 

 glossy as that of the ordinary silkworm, it is strong, smooth, and 

 serviceable, and capable of being woven into fabrics of much 

 utility. 



The well-known Eria silk of India is produced by an insect 

 closely allied to the Atlas Moth, Altacus ricini. This silk is very 

 loose in texture, and, being without gloss, has a rather flimsy look. 

 In reality, however, it is possessed of peculiar strength. 



One large species of silk-producing moth, also allied to the 

 Atlas, is the Ailanthus Silkworm. The Acclimatization So- 

 ciety is endeavoring to introduce this useful insect into this coun- 

 try, and so to make England a silk-producing country. We have 

 not sufficient mulberry-trees to feed silkworms in such numbers 

 as would make their employment profitable, and thus the ordi- 

 nary silkworm is rather beyond our reach. But the insect in 

 question feeds on the Ailanthus glandulosus, a tree which has been 

 imported from China, and thrives wonderfully in the open air. 

 In March, 186-1, 1 saw a young sapling about three feet in height 

 that had sprung from a seed sown in March of the previous year. 



This insect is very hardy, and after it has been hatched and 

 fed for a little time like the ordinary silkworm, it is laid on the 

 growing leaves and left to shift for itself. The caterpillar is 

 nothing of a wanderer, and does not attempt to straggle from 

 the tree, being content to stay and make its cocoon among the 

 branches. The moth is colored like the Atlas, being mostly of 

 a grajnsh-yellow, with some markings of dull violet, and some 

 spots of black and white. The caterpillar is green marked with 

 black. 



There is a North American species of moth — also one of the 

 Atlas Moth's numerous allies — which displays a wonderful piece 

 of ingenuity in suspending its cocoon. This is the insect called 

 Saturnia Promethea, which lives in the sassafras-tree. The cocoon 

 is placed within the leaf of the tree and secured by a strong web ; 

 but as the leaf would fall before the moth could escape, a strange 

 instinct is implanted in the insect, which fastens the stem of the 

 leaf to the branch by sundry silken threads, so that, although it 

 may wither and part from the branch, it can not fall to the 

 ground. 



We now pass to the second insect represented in the illustra- 

 tion. This is the House-builder Moth (Oiketicus Sandersii), an 



