108 I3RITISH BUTTERFLIES. 



The caterpillar is green, darker on the back, and 

 paler at the sides, it feeds on the water dock. 



The butterfly used to be found in July and August, 

 being formerly especially abundant about Yaxley and 

 Whittlesea Mere, and has been taken also at Benacre, 

 Suffolk; and Bardolph Fen, Norfolk. 



Various reports of its capture, during the last two or 

 three years, have been published ; but they all seem to 

 require confirmation. 



This butterfly is now generally considered to be a 

 large local variety of the continental one called Hippo- 

 thoe'j with which it closely agrees in its markings. 



THE BLUES. (Genus Polyommatus.} 



WE now arrive at a numerous genus of elegant and 

 lively little insects, collectively known as the " Blues," 

 though some of them are not blue at all. In their 

 manners, and the localities they inhabit, there is so 

 much in common, that one description of these will 

 answer for nearly every one of them ; so that my small 

 available space will be in great part devoted to pointing 

 out the marks of distinction between the various species, 

 ten in number, several of them closely resembling 

 others in general appearance, and requiring some care 

 in their discrimination. 



Their caterpillars, which are wood-louse shaped, or 

 onisciform, generally feed on low plants, chiefly of the 

 papilionaceous order; and the butterflies are found in 

 dry meadows, on downs, and in open heathy places. 

 The first species, P. Argiolus, is, however, an exception 

 to the above, both in its food and haunts. 



Several species of this genus are often found toge- 

 ther. For example, in the Isle of Wight, last August, 

 I took P. Argiolus, Cory don. Adonis, Alexis, and Agestis, 

 all within about one hour, and a space of a few yards 

 square in the corner of a field. 



