195 



THE REGULAR TEMPERATURE VARIATION IN 

 VANESSA UKTICM. 



By T. Reuss. 



V. urticce var. aniploides var. falcoides. 



The above figure depicts in its left half a form of T'. urticce, 

 which I will call var. aniploides, with relatively broad wings and 

 almost straight marginal wing-border in the fore wings ; the 

 second costal blotch is broadest next the median nervure, and 

 the outlines of the spot are almost straight. The right-hand 

 half of the figure shows a form which I will call var. falcoides. 

 The wings are comparatively narrow, with strongly curved outer 

 marginal border, in extreme specimens approaching the shape 

 of P. c-album. The second costal blotch is deeply dentated in 

 outline, and the costal part is broadest. The details here de- 

 scribed appear to be the only ones in V. urticce* that regularly 

 obey the influence of temperatures either above 15-20° C. (var, 

 amploides), or below 15-20° C. {y?iY. falcoides), and both forms 

 are larval forms, not pupal — i. e. the pupae of larvfe bred in 

 warmth and sunshine will emerge as the form amploides, even if 

 kept in the cool and dark, while larvae reared in the shade and 

 exposed to the cool night air will produce /a/coic^es, even if the 

 pupae were immediately transferred to heat and sunshine. 



The " normal " form of V. urticce appears from larvas 

 which, as in nature, are exposed at night to temperatures 

 much below and by day {if it is a sunny day) much above 

 15-20° C. The normal specimens of V. urticce are intermediate 

 between amploides and fdcoides ; sometimes a falcoid costal 

 blotch goes with an amploid marginal outline and broad wings 

 (this combination is normal in the Corsicau var. ichnusa, in 



* I reared and set over seven hundred specimens from fifteen batches of 

 ova for reference on these points especially this season. The two specimens 

 figured belong to brood vii. 



p2 



