THAUMETOPCEA. I 27 



It expands about an inch or a little more. 



The antennae arc light brown, the head and thorax ashy- 

 grey, and the abdomen brownish, with a dark brown anal tuft. 

 The fore-wings are ashy grey, clouded with darker. At the 

 base is a dark grey transverse line, and another similar one 

 just beyond it, running obliquely across the wings. A third 

 rather undulating line runs beyond the middle, and approaches 

 the second at the inner margin. Between these two lines 

 is usually a blackish dot. The hind- wings are whitish, with 

 a faint dark grey transverse line, which is sometimes slightly 

 thickened at the inner margin. The fringes of all the wings 

 are chequered with light and dark grey. The under side 

 is whitish grey, with the markings of the upper side scarcely 

 indicated. The female is larger than the male, and has usually 

 two indistinct dusky bands on the fore-wings, with a dark dot 

 between them. 



The larva feeds on oak from May to the beginning of July. 

 It is covered with light grey hair, and is bluish-black on the 

 back, and whitish on the sides, with two orange or pale ^rey 

 hairy warts on each segment. 



The larvae live gregariously under a web, and are remarkable 

 for their carefully arranged migrations, which are conducted by 

 travelling in file or procession. Their destructiveness, and the 

 inflammation set up by the hairs on the human skin, cause 

 them to be much dreaded in some places. 



The pupa, which is ochre-yellow, with two short spikes at 

 the posterior extremity, is enclosed in a dense, reddish-brown 

 cocoon, with interwoven hairs. The moth may appear in 

 about five weeks, or not till the following year. 



