342 PTER0PH0RUS BERTRAMI. 



mandibles are reddish-brown ; the frontal plate is 

 gradually becoming pale like the head, the black 

 being confined to the front in some specimens, in 

 others to a black edging, more or less broken all 

 round. The ground of the ventral area and the pro- 

 legs are uniformly glaucous-green, and the anterior 

 legs are now ringed with black only. 



In the adult stage, about half to five-eighths of an 

 inch, the larva has a still paler appearance. The 

 ground colour is bright pea-green ; the head is very 

 pale straw-colour, faintly tinged with green; the 

 large ocelli are intensely black, and consequently 

 very conspicuous ; the mandibles are reddish-brown ; 

 the frontal and small anal plate are of the same 

 bright green as the ground colour; the dark green 

 (slightly brownish anteriorly) pulsating dorsal vessel 

 forms the dorsal stripe ; between it and the spiracular 

 region are two greyish-white stripes, on which the 

 small black tubercular spots may be seen ; below the 

 spiracles is a still clearer and more conspicuous white 

 stripe ; the spiracles are black. 



The ventral surface is uniformly of the same bright 

 green of the dorsal area ; at the front, and at the base 

 of each anterior leg, is an intensely black spot ; and 

 the prolegs are finely margined with black. 



It feeds in the shoots of yarrow, apparently pre- 

 ferring the central shoot, and eating downwards 

 towards the root. 



It will be noticed from Mr. Buckler's description 

 of the larva of P. dichrodactylus (E.M.M., Vol. XII, 

 233), that both species correspond in having three 

 forms of colouring in the different stages of growth, 

 and the resemblance of the adult larvae particularly 

 shows the close relationship of the two species ; whilst 

 the differences, apart from the food-plants, are suffi- 

 ciently wide to separate them. 



When full-grown the larva leaves the shoot, and 

 affixes itself by the tail to the outside of the stem, 

 leaf, etc. 



