58 THE ENTOMOLOGIST. 
females, were captured; next morning, after a slight fall of snow 
in the night, I caught three more males in the same locality. All 
the twelve (seven males, five females) were put in one cage to breed. 
The males were much excited, and sought the females eagerly ; 
pairing quickly followed, and only lasted a few hours. I noticed 
that they flew towards the lamp which was in the room. Eggs 
were laid the same night. The female extends the ovipositor 
and feels about with it until a favourable place for laying is 
found; she deposits the eggs singly, but often lets a little heap 
of twelve or so fall into the cracks and corners, and thus the 
business of laying is soon over. She lives for some time after, 
as long as thirteen days I noted, but does not move about at all. 
‘his species 1s always found singly, two hardly ever appearing 
on one tree, and the female flies about in the cage while laying 
her eggs; thus I conclude that she would fly fast in the open 
air, rushing in and out among the birch branches, and laying her 
eggs singly, about a yard above ground; for the larve always try 
to climb higher as soon as they emerge. ‘The numbers of eggs 
deposited by the five females respectively were 300, 271, 217, 200, 
and 180; hardly 3 per cent. were infertile. 
The nae is hemispherical, and very soft, hardening in about 
eight or nine days, the colour changing from light green to violet 
and dark brownish grey, almost to chocolate. As soon as the 
colour changes from light green to dark brown, which it does by 
degrees, the surface of the egg becomes sprinkled with little 
brown dots, like grains of sand, which finally coalesce and 
disappear in the grey-brown. 
The LARVA emerges in about twenty-eight to thirty days; 
its length is then about 2 mm., colour dull green with 
brown head; a week later it measures 7 to 8 mm. and 
turns a darker green. Immediately on emergence it begins 
to loop, and after devouring the egg-shell (which frequently 
does not take place), it tries to climb up higher. The 
larva spins diligently while young, hanging on to the stems 
and leaves; it eats away the upper side of the latter, so 
that numbers of young birch leaves have nothing but the 
veins left. he first change occurs in five or six days, when the 
caterpillar assumes a darker green, and can scarcely be distin- 
cuished from the green of the birch leaves. After the second 
change it becomes still darker, the claspers turn black, and the 
