14 CIMBEX LUTE A. 



pale testaceous, femora broadly marked with black 

 above. $ 



d. Black; antennae for the greater part and tarsi 

 reddish-luteous ; wings clear hyaline. $ 



e. Yellowish-testaceous ; the head, breast, back of 

 thorax, and base of abdomen, fuscous. 



The luteous forms of lutea are readily separated from 

 the normal forms of sylvarum, which have always the 

 head, thorax, and the greater part of the legs bluish- 

 black ; but the lighter-coloured aberrations of sylvarum 

 come very near the darker-coloured specimens of lutea. 

 These, however, may be always separated from sylva- 

 rum by the pubescence, which in the former is thick, 

 moderately long, and alway griseous, pale or yellowish, 

 never fuscous as in sylvarum-, which has it somewhat 

 longer, but not so close. The hair on the abdomen in 

 sylvarum is also longer, more scattered, and not so 

 silky as in lutea. The wings in lutea are more yellow- 

 ish, and there is no fuscous cloud in the median 

 cellule, nor has the apex a fuscous border. 



The reddish-banded males of sylvarum are easily 

 separated from those of lutea, which have always the 

 abdomen black, except with Ab. a; but that again has 

 sufficient distinctive characters in the colour of the 

 head, thorax, and wings. The only characters that I 

 can find to separate the black males of sylvarum from 

 lutea are, that the median cellule of the former has a 

 fuscous cloud, and the apex of the wings is always 

 fuscous, and the club of the antennae is shorter and 

 thicker, being not much longer than the two preced- 

 ing joints ; in lutea they are not so distinctly pyriform, 

 and are considerably longer than the two preceding. 

 The wings in lutea g appear to have a well-marked 

 steel-blue iridescence, but I do not know if this is a 

 constant characteristic. 



The larva feeds usually on Salix alba and S.fragilis. 

 Its body is bluish-green, the skin is in folds, and over 

 the legs and along the sides are small white tubercles. 

 Along the back is a dark bluish, central stripe, which 



