150 THE COLOUES OF ANIMALS 



Experiments upon the larvae of Geometrae and Noctuae 



The experiments were then extended to many 

 other dark-colom-ed larvae (chiefly Geometrce). The 

 method of experiment was as follows : a larva which 

 resembles the twigs or bark of its food-plant was 

 selected, and was surrounded by the leaves upon which 

 it fed, and by white or green surfaces. No brown 

 twig or anything dark- coloured was allowed to come 

 near it during its whole life. Under these circum- 

 stances the larvae, in the majority of the species selected 

 for experiment, became very light brown or light grey 

 in colour, and quite unlike the darker larvae of the 

 same kinds which were produced when an abundance 

 of dark twigs had been mixed with the leaves of the 

 food-plant.^ 



The results were certainly protective, for the 

 lighter larvae were far less conspicuous on the green 

 leaves and stems than the darker ones would have 

 been. At the same time it must be admitted that the 

 resemblance of the darker forms to the dark branches 



• These experiments have been successfully applied to the .follow- 

 ing GcoinetrcB : — Crocallis elinguaria (for two seasons), Ennomos 

 anrjularia, E. hmaria, Boarmia rhomboidaria (this species was inves- 

 tigated by my friend and pupil, Mr. E. C. L. Perkins, B.A., of Jesus 

 College, Oxford), B. roboraria; and to one of the Noctuce, Catocala 

 sponsa. Since this note was written, I have found, during the past 

 summer (1889), that the Geometer Heterophylla abruptaria, and the 

 Noctuas Catocala electa and C. elocata, are also sensitive, the first and 

 last named to a marked degree. 



