RESEMBLANCE TO BIRD DROPPINGS 199 



leaf.^ The resemblance may be either to a dropping 

 which, fallen from a height, has spread out to form a white 

 and mottled grey patch on a leaf, or to one which has 

 kept its cylindrical shape, and appears dark grey or 

 grey-brown and white. 



The young caterpillars of Papilio dardanus much 

 resemble the latter object, and their very sluggish habits 

 contribute considerably towards the illusion. 



The former class is well exemplified by a beautiful 

 Geometrid moth ^ which rests with outspread wings fully 

 exposed on the surface of a leaf. The wings are of a chalky 

 white hue, with wavy darker lines, and in the centre of 

 the fore wing is a dark, irregular patch of black and brown, 

 glistening here and there with silver. The whole produces 

 an effective likeness, which must be seen in its natural 

 surroundings to be believed. If the moth is frightened 

 it flies away, but takes up the same exposed position on 

 another leaf. 



A propos the silver marking, it is curious how rare 

 silver is on insects ; gold is perhaps commoner. Besides 

 the above case, the under surfaces of Fritillary and 

 some other butterflies, and the marks on some Plusia 

 moths, I have only seen one other insect with silver — a 

 large Saturnid caterpillar, green, with humps on the 

 back covered on one side with pure silver. The attempt 

 to rear this beautiful caterpillar was unsuccessful, so the 

 name cannot be given. 



Certain insects which resemble bark, and are to be 

 found on tree trunks, are very wonderful examples of 

 procrypsis, though whether it is special or general pro- 

 crypsis is a matter of words only. 



Many Lasiocampidae have caterpillars which are seen 

 with difficulty when at rest, so closely do they lie against 



1 First recorded by Sidgwick in the Journal of the Rugby School Natural 

 History Society. 



^ Problepsis cegretta. 



