49 



and they are often named by naturalists 

 from the plant on which they feed. As the 

 papilio urtica^, or tortoise-shell butterfly, 

 is never found on any plant but the sting- 

 ing nettle ; there are others which feed 

 only on two different plants as the phalaena 

 verbasci, water-betony moth, which will 

 eat either the mullein or water-betony, 

 but these are comparatively scarce to 

 the former, and much less common than 

 either is tlie brown-tail moth*, which 

 in the summer of 1783, committed so 

 much mischief on all the trees and herb- 

 age near London, that the whole coun- 

 try was very much alarmed : inasmuch 

 as advertisements, paragraphs, letters, &c. 

 almost without number were published, 

 and which spread great consternation 

 about the country. Some idea of their 

 number may be calculated from the fol- 

 lowing account, which I shall extract from 

 a history of this caterpillar, which was at 

 that time published by mypartner, the late 

 Mr. William Curtis : " In many of the pa- 



* Bombyx phaeorhea. 

 D 



