( 311 ) 



XVIII. Experiments in 1893, 1894, and 1896 upon the 

 colour-relation between lepidopterous larvfB and 

 their storro^cndings, and especially the effect of 

 lichen-covered hark upon Odontopera bidentata, 

 Gastropacha quercifolia, etc. By Edward B. 

 PouLTOxV, D.Sc, M.A., LL.D. (Princeton), F.R.S., 

 etc., Hope Professor of Zoology in the Univer- 

 sity of Oxford, Fellow of Jesus College, Oxford. 



[Read June Srd, 1903.] 



Plates XVI, XVII, and XVIII. 



The circumstances under which the experiments re- 

 corded in the present memoir were undertaken, afford a 

 good example of the stimulus and encouragement to work 

 rendered possible by that mutual intercourse and exchange 

 of experience and ideas which are promoted by meetings 

 of scientific societies. 



In the year 1892 I conducted an extensive series of 

 experiments upon the adjustment of the colours of the 

 larvffi of Amphidasis bcttdaria to those of their environ- 

 ment (Trans. Ent. Soc. Lond., 1892, pp. 337-3G9). Living 

 examples of the chief results obtained were shown at the 

 meeting of Section D of the British Association at Edin- 

 burgh, on August 9th (Report of the 1892 Meeting, p. 

 786, where however the word " pupffi " is erroneously 

 printed instead of " larvse "). After the larvae had been 

 exhibited, Dr. Stacey Wilson, of Birmingham, asked if I 

 had tried the effect of lichen-covered bark. Dr. Wilson 

 stated that he had once beaten the larva from a food- 

 plant with twigs covered by lichen, and that its appear- 

 ance was entirely different from that usually borne by 

 hctularia. He looked upon it, in fact, as the larva of 

 some otlier species, and was only convinced by breeding 

 tlie moth (Trans. Ent. Soc. Lond., 1892, p. 360). The 

 idea of making use of an environment of lichen-covered 

 bark had not occurred to me, and I determined to try 



trans, ent. soc. lond. 1903. — part in. (oct.) 



