THE ENTOMOLOGIST. 



Vol. XXIL] JANUAEY, 1889. [No. 308. 



ON THE VARIATION OF INSECTS. 

 By T. D. a. Cockerell. 



At all times, and more especially of late years, the various 

 deviations from the type-form presented by insects have excited 

 considerable interest in the minds of entomologists ; and, as a 

 result of this, scarcely a number of an entomological magazine 

 can be found which does not contain soine reference to varietal 

 forms. Nevertheless, the attempts to classify these numerous 

 varieties have been very few, the most notable that I can recall 

 being that of Mr. Jenner Weir in the 'Entomologist' (Entom. 

 xii. 153), while little or nothing has been done towards 

 ascertaining the causes of variation, or even recording the 

 obvious accompanying circumstances. 



The present paper is intended rather as an indication of the 

 manner in which varieties may be classified than any final 

 arrangement of them, and seeks to stimulate such interest in the 

 matter that its suggestions may be pat to the proof, and confirmed 

 or discarded in favour of better ones. The varietal names used are, 

 as far as possible, in accordance with the " Code of varietal nomen- 

 clature," already proposed in the ' Entomologist,' but many forms 

 have had names applied to them by authors which are not the 

 most convenient. These, in obedience to the law of priority, 

 have been retained. 



Class I. — Colour Varieties. 

 a. Intensification of Colour. 

 Examples. — Pieris rapce, var. novanglice, Scudd., and var. 

 manni, Mayer. Vanessa himtera, var., with the (typically white) 

 spot on the inner side of the black patch on the apex of the 

 primaries yellowish (Maynard). Bnjophila perla-flavesccns, 

 Entom. XX. 240 ; also " an orange variety," Proc. S. Lond. Ent. 



ENTOM. — JAN. 1889. B 



