10 CIMBEX SYLVARUM. 



species of Cimbex. The variations in the coloration 

 are very numerous in both sexes. Commencing with 

 quite black specimens save the antennae and tarsi, we 

 meet with specimens having one yellow band on the 

 abdomen, then with specimens with two or three bands, 

 which lead into specimens with the middle of the abdo- 

 men entirely yellow, the tibiae being also yellow, and 

 from this we reach the extreme yellowish form de- 

 scribed above as Ab. e. We find the same variations 

 with the red banded forms. 



The larva feeds on birch, and is found from July to 

 September. Its head is pale yellow, granular, and 

 with black eye-spots, the body is green, more or less 

 yellowish at the skin folds and along the back, where 

 there is a black stripe, which is bluish along the centre, 

 and is widest towards the middle of the body, it being 

 very narrow along either end. The skin is wrinkled, 

 especially on the sides, which are beset with numerous 

 white warts, particularly over the legs. The feet are 

 white, with brownish claws ; the spiracles black, longer 

 than broad, and broader below than above ; they arise 

 from a raised part of the skin. 



When young the larva is greenish-white, dusted over 

 with white powder. It wants the black dorsal stripe 

 entirely. 



Brischke and Zaddach (1. c., p. 237, pi. ii, fig. 2) 

 describe and figure a larva which was found by Drew- 

 sen and by themselves on beech ; this is described as 

 being the largest of all the Cimbex larvae. The ground 

 colour of the body is a beautiful bluish-green, the 

 dorsal stripe is clear blue or violet ; the head is larger 

 and more cubital than with sylvarum, and the white 

 tubercles are smaller and more pointed. According 

 to Brischke the characters presented by this larva are 

 constant, and if that be so the chances are that it per- 

 tains to a good species ; but unfortunately Drewsen 

 and Brischke and Zaddach bred only males, which 

 cannot be separated apparently from G. sylvarum, and 

 like the males of that species would seem to be very 



