EARTH-MASON CATERPILLARS. 175 



regular, in which the cocoon or the chrysalis lies secure 

 (Fig. B, p. 176). The polish of the interior is precisely 

 such as might he given to soft earth by moistening and 

 kneading it with great care. But beside this, it is usually 

 lined with a tapestry of silk, more or less thick, though this 

 cannot always be discovered without the aid of a magnify- 

 ing glass. This species of caterpillars, as soon as they have 

 completed their growth, go into the earth, scoop out, as the 

 cossus does in wood, a hollow cell of an oblong form, and 

 line it with pellets of earth, from the size of a grain of sand 

 to that of a pea — united, by silk or gluten, into a fabric 

 more or less compact, according to the species, but all of 

 them fitted for protecting the inhabitant, during its winter 

 sleep, against cold and moisture. 



Outside view of Xests of Earth-mason Caterpillars. 



One of the examjjles of this occurs in the ghost-moth 

 (Hepialus humuli), which, before it retires into the earth, 

 feeds upon the roots of the hop or the burdock. Like 

 other insects which construct cells under ground, it lines 

 the cemented earthen walls of its cell with a smooth 

 tapestry of silk, as closely woven as the web of the house- 

 spider. 



Inaccurate observers have inferred that these earthen 

 structures were formed by a very rude and imskilful process 

 — the caterpillar, according to them, doing nothing more 

 than roll itself round, while the mould adhered to the gluey 

 perspiration with which they describe its body to be 

 covered. This is a process as far from the tiTith as 

 Aristotle's account of the spider spinning its web from wool 

 taken from its body. Did the caterpillar do nothing more 

 than roll itself in the earth, the cavity would be a long 



