Notes in 1887 upon lepidopterous larve, éc. 598 
the larve of this and other species has already been 
pointed out by Prof. R. Meldola (Proc. Zool. Soc., 1878, 
p- 155, and editorial notes to the translation of Weis- 
mann’s Essay, ‘On the Origin of the markings of 
Caterpillars,’ p. 305). In the former paper the author 
calls attention to the interesting fact that the young 
larve are brown, and remain brown during hybernation, 
when the trees are bare, while many of them become green 
when older, after the leaves have expanded in spring. 
A purely accidental observation has enabled me to 
showthat the younger larve possess the power of adjusting 
the shade of their brown colour to that of the twigs 
of their food-plant. In the autumn of 1887 a number 
of these larve, which had been reared from ova, were 
placed in two muslin bags, tied upon different branches 
of the same birch-tree. The larve were examined on 
May ist, 1888. In one bag 27 larve were found, in the 
other 4, while 4 larve were found upon the tree, having 
evidently escaped from the second bag. The 8 larve 
were much lighter in colour than the others, the difference 
being independently noticed by my wife and myself. 
Examination of the twigs which had been enclosed in 
the bags at once showed that their colour corresponded 
with that of the larve. The bag containing the 8 larve 
had been tied on to a part of the tree which had been 
largely pruned earlier in the year, and the enclosed 
twigs were young and comparatively light-coloured. 
The necessity for such protection is especially important 
in this species during hybernation, when its enemies 
are often compelled by hunger to search for food in the 
most careful manner. 
After hybernation the larve grow rapidly, and in the 
last stage become dimorphic, some of them being 
green and some brown. After experimenting for two 
seasons I failed to obtain evidence of any susceptibility 
on the part of the larve during this stage: dark 
surroundings did not make a larger proportion of larvae 
brown, nor did green surroundings make a larger pro- 
portion green. It will be shown below that these colours 
are certainly hereditary, like those of the Ephyride. 
The larve in the last stage are protected by their 
close resemblance to catkins. They feed upon catkin- 
bearing trees, hazel and birch. The brown posterior 
end of the body exactly suggests the brown scale at the 
