THE BROWX-TAIL MOTTI. 39 



the long barbed hairs (Plate 9, Fig. 5) nor by the white 

 branching hairs (Plate 9, Fig. 1), but by the very minute 

 barbed hairs which we call the nettlins: hairs, occurrinir in 

 yery great numbers on the subdorsal and lateral tubercles 

 of segments 5 to 12 inclusive (Plate 9, Fig. 3), and also on 

 the tubercle at the base of the long spines (Fig. 4) . These 

 nettling hairs are very small, only about one two hundred 

 and fiftieth of an inch in length, very sharp at one end, and 

 with two or three barbs at the other end and many along 

 the sides. These barbs are so arranged that when these 

 nettling hairs fall upon the skin any movement Avill cause 

 them to work into the flesh. 



The nettling of the skin may be caused by contact with 

 the caterpillars in either of the last two molts, the cocoons, 

 or to some extent with the moths ; but contact is not neces- 

 sary, as these fine nettling spines may fall or be blown by 

 the wind. Cases are on record in Encfland of travellers 

 being affected when the wind blew strongl}' from infested 

 hedges along the side of the road. 



A careful examination of the caterpillars in each molt 

 shows that the . nettling spines do not occur except in the 

 last two stages, or after the row of white spots appear along 

 each side of the caterpillar. A great (juantity of these 

 nettling spines are alwaj^s i^rcscnt scattered through the 

 cocoon and more or less over the surface of the pupa, but in 

 every case they appeared to have come from the last larval 

 skin, and never to have developed from the pupa\ An 

 examination of a large number of moths of both sexes 

 showed many of the nettling spines scattered over the sur- 

 face of the wings and body in a very irregular manner, 

 none of which were attached to the integument, but merely 

 lodged among the hairs and scales of the imago. Only a 

 few of the nettling spines were found on some specimens, 

 Avhile on others a lari>'e number occurred. In a few cases 

 many of these spines were found in a confused mass in one 

 spot, while on another not a single one occurred in that 

 particular place. We nuist conclude, therefore, that as the 

 caterpillar spins its cocoon these spines become scattered 

 and lodge throughout the fabric, some of them falling on to 



