1885.] Colouring of Phytophagous Larvce. 297. 



different foods which have been found to be associated with particular 

 colour variations of the larvae in field observation. Mr. Meldola 

 mentions a paper by Mr. R. M'Lachlan ("Trans. Ent. Soc," 1865, 

 p. 453) entitled " Observations on some remarkable Varieties of 

 Sterrha Sacraria, Linn., with general notes on Variation in 

 Lepidoptera." In this paper Mr. M'Lachlan gives some valuable 

 data as to Eupithecia Absynthiata. The author collected about 100 

 larvae of this species. When found upon Senecio Jacobcea they were 

 yellowish, upon Centaurea nigra reddish, and upon Matricaria 

 whitish. When nearly full grown they were all given Senecio 

 Jacobcea, but this change of food did not affect the colour of the 

 reddish and whitish varieties. From this Mr. M'Lachlan argned (1) 

 that it was necessary for the larvae to have fed on the one kind of 

 flower from the egg to acquire the resemblance, and (2) that the 

 colour is not caused by the food showing through the somewhat 

 transparent integument. He thinks that variation may be indirectly 

 caused by the food, and he points out the similarity of internal 

 feeders. He also concludes that the indirect effect of the food in 

 producing protective resemblance is normal, and the facts of opposite 

 colouration must be due to other circumstances. 



14. Experiments upon the Larvce of S. Ligustri. 



Mr. Meldola quotes (in the editorial notes) Mr. Argent for the 

 observation that this larva is of a darker green when found upon 

 laurustinus than when feeding upon lilac. He also quotes Mr. Davis 

 for the opinion that the larvae upon ash are of a more greyish-green 

 than those upon lilac or privet. My own experience has always been 

 that the larvae are much duller in both the ground colour and the 

 purple stripes when feeding upon lilac than when occurring upon 

 privet. Those upon ash resemble the lilac forms. Mr. Davis' 

 expression " greyish-green " exactly explains the difference between 

 the lilac and privet forms (being applicable to the former). The 

 privet varieties have a much brighter yellow ground colour, and 

 the stripes are of a more vivid and redder purple, while the purple in 

 the lilac forms is bluer and altogether duller (often tending towards 

 brownish). Having often observed these differences in the field, I 

 experimented upon some larvae during the summer of 1884. The 

 larvae from a batch of eggs were divided into three lots and fed 

 throughout their life upon lilac, privet, and ash respectively. The 

 larvae upon ash did not flourish, but about twelve of the privet larv» 

 and six of the lilac arrived at maturity, and without exception showed 

 the differences I have indicated above. The results of these experi- 

 ments have been communicated to the Entomological Society of 

 London, and the two varieties figured, in a paper not yet published. 



