between le'imlopterous larva} and their surrO'uniHngs. 315 



of Gastropacha riuercifolia by Mr. W. Holland, on July 

 22nd, 1893, enabled me to experiment on this interesting 

 sj3ecies, which is well known to present grey and lichen- 

 like forms. The company, evidentl}' the product of a 

 single batch of eggs, was so numerous that I was able to 

 start four experiments with fifteen larvae in each, on 

 July 28th. All were fed on hawthorn, the food-plant on 

 which the larvte had been found. This in three cases was 

 intermixed with environments more or less harmonizing 

 with known varieties of the larva — the rough black-barked 

 twigs of the Turkish oak, bramble-stems of a rich reddish- 

 brown colour, and sticks bearing an abundant growth of 

 lichen (probably Bamalina farinacca in all cases). In the 

 fourth case the larvae were as far as possible restricted to 

 the green leaves and youngest shoots of their food-plant. 

 It was, however, impossible altogether to exclude shoots 

 of greyish and reddish-brown shades, and these probably 

 produced some effect. 



At first the young larvae rested chiefly on the food- 

 plant, but soon preferred the bark of the older wood. The 

 change took place simultaneously in each of the three 

 sets containing dark bark and lichen, as will be seen by 

 a glance at the following summary of Mr. Holland's careful 

 notes : — 



* 3 on musHn roof. f 1 missing. 



There is no reason to suppose that these effects were 

 due to any gradual recovery from disturbance. The re- 

 cently hatched larvae were found at the tip of a young 

 shoot on July 22nd, and it is probable that by August 5th 

 the period had been reached when they begin to seek the 

 older wood for the diurnal rest. After August 9th only 

 single larvae were found except upon the environments 

 which had been provided, and it is probable that, under 



