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VI. Experiments in 1909 and 1910 upon the colour- 

 relation between lepidopterous larvae and pupae 

 and their surroundings. By Elizabeth Bridges. 

 Communicated by Prof. E. B. Poulton, D.Sc, 

 M.A., F.R.S., etc. 



[Read November 2nd, 1910.] 



I. Experiments on the larva of TJropteryx sambucaria. 

 II. Transference experiments on the same. 



III. Experiments on the pupa of the same. 



IV. Note on some experiments on the larva of Odon- 

 t opera bidentata. 



V. Notes on the apparatus used. 



I. Experiments on the larva of U. sambucaria. 



The following experiments were undertaken with the 

 object of finding out to what extent the close resemblance 

 of certain lepidopterous larvae to their surroundings is 

 due to the adaptive power of the individual. Prof. 

 Poulton * has already shown that several species (notably 

 R. crataegata, A. betularia, 0. bidentata, G. queori folia, 

 etc.) do possess in a remarkable degree the power of 

 assuming the colour of their surroundings, and in the 

 summer of 1909 he kindly gave me some eggs of Sam- 

 bucaria, and suggested that I should test this species in 

 the same way. The results of the experiments show that 

 it is one of the most sensitive hitherto investigated. I 

 will briefly describe the experiments, before giving the 

 details in tabular form. 



As is well known, the larvae of most Geometers feed 

 only at night, and spend the day motionless in a twig- 

 like attitude on the woody part of the food-plant, which 

 in many cases they closely resemble. Prof. Poulton found 



* Trans. Ent. Soc. Lond., October 5, 1 '.ton, and December 1892; 

 and "Colours of Animals," Lond., 1890, pp. Ill, 11-. 

 TRANS. ENT. SOC. LOND. 1911. — PART I. (MAY) 



