170 
NYMPHALIDAE 
immediately noticed a hissing sound, not unlike the hiss of a 
snake, produced by the large number of butterflies nibbing 
their wings together ; a habit peculiar to the Vanessidae. The 
noise is made by the sudden expansion of the wings, causing 
the inner margin of the fore wing to rub against the costal 
margin of the hind wing, this resulting in a chafing, stridulous 
sound. 
This butterfly occasionally makes its appearance in the 
winter months during fine, warm spells of weather, and in 
exceptional cases, when snow covers the ground. Some years 
ago, on February 14th, one was seen on the wing at St. Tudy, 
Cornwall, when snow four inches deep covered the ground. 
Egg Laying. During May the female butterfly may be 
seen in the act of laying its eggs, hanging with closed wings 
to the under side of a Stinging-nettle leaf. The eggs are 
deposited in a dense mass numbering 450 or 500, piled up 
one above the other, being six or more deep in the middle. 
1 he time occupied in laying the one batch is over two hours. 
On May 12th of one year I captured four females of this 
butterfly and kept them confined on plants of Nettles. On 
the 16th, at noon, all four started at the same time laying 
their eggs, each hung motionless, except for the movement 
of the abdomen. It appears remarkable that all four butterflies 
should have chosen exactly the same time for the purpose, 
as the weather condition was similar to that on the previous 
days. 
Egg. The egg is very small in proportion to the butterfly, 
being only O'So mm. high, of an oblong shape, and clear 
yellow-green in colour, with eight longitudinal glassy-white 
keels running from the base to the crown, where they are 
elevated and prominent, resembling in structure fluted frosty 
glass. The egg state lasts fourteen days. All hatch at once ; 
the little larvae at the bottom of the batch immediately start 
eating through the leaf and all live in a mass in a web spun 
over the leaf. The larvae of the Peacock are gregarious 
through all their stages, moulting four times, and preparatory 
to each moult they all assemble in a dense mass, resting on 
a carpet of web. 
Larva. When fully grown the larva averages about 41 mm. 
in length. The ground colour is velvety-black ; from the 
