VI. 
Colour Changes in Insects. 
HE question of the variation in colour and markings exhibited by 
many species of lepidoptera, in both their preparatory and 
perfect stages, has, during the last few years, received much atten- 
tion, and given rise to not a little controversy. A general protective 
resemblance of insects to their surroundings has long been an 
accepted fact with most naturalists, and no one would deny that the 
special and often highly perfect likeness of caterpillars to twigs and 
imagines to leaves, is of value as a protection; but on the meaning 
of the variation in colour of a species with reference to its surround- 
ings, less certainty has existed. This most interesting subject was 
brought into prominent and public notice in 1890, by Poulton, in his 
well-known book, ‘“‘ The Colours of Animals” (pp. 110-158). Some 
doubt has lately been expressed as to certain of his deductions. His 
recent publication (1) of the details of several years’ experiments, of 
which only some of the leading results were given in ‘‘ The Colours 
of Animals,” is, therefore, of value, and a short review of the questions 
raised may be of interest. 
The only larve of Noctuid moths on which Poulton experimented 
were those of Hadena oleracea, Euplexia lucipara, two species of Mamestra 
(M. brassice and M. persicae), and four of Catocala (C. sponsa, C. nupta, 
C. fraxini, and C. elocata), The Mamestvye showed no power of colour- 
adaptation, some green caterpillars of M. persicae turning brown on 
green leaves. Most noctuid larve feed by night, hiding in earth by 
day, and colour is consequently of minor importance to them. The 
Catocala larvee, which in their form and habits approach geometers, 
were rather sensitive to environment, tending to become darker when 
black twigs were mixed with their food, than when among green 
leaves and shoots only. Poulton’s results with these two genera are 
confirmed by Miss Gould (2). No certain results were obtained with 
the larvee of Hadena and Euplexia. 
The only geometrid caterpillar which was not proved sensitive to 
its environment was that of Ephyva annulata (omicyonaria). All others 
on which experiments were made were darkened by placing black twigs 
among their food. Such were the larve of Ennomos quercinaria (angulana), 
Selena lunaria, Melanippe montanata, Phigalia pedania ( pilosaria), Hemero- 
phylla abruptaria, and Crocallis elinguaria. All these were light brown 
among green leaves and shoots. The last-named caterpillars were 
