I04 YORKSHIRE NATURALISTS UNION. 



the young g;reen twig^s near the leaves. What he did not find 

 out was hovV a black larva knew a black stem from a g^reen one, 

 and vice versa as reg'ards the green larvse. 



During- the lecture in which Professor Poulton detailed the 

 fact I have just noted, he g^ave the results obtained by feeding 

 larvEe of the same brood, on a variety of foods having the leaves 

 or the stems of the plants of different shades of colour, and also 

 by keeping them in cages of different coloured glass, or wood 

 painted in different colours, in pretty much the same way as Mr. 

 Merrifield afterwards made experiments on pupee, and .with 

 exactly the same results. Professor Poulton found that the 

 larvce strongly partook of the colour of the food and environ- 

 ment, and from the same batch of eggs he was able to produce, 

 of covirse within limits, larvae of almost any shade of colour he 

 wished. Some species, as was to be expected, were much more 

 sensitive than others, but probably even the least sensitive would 

 in the course of two or three generations continued on the same 

 colours, gradually give way to the influence. At the close of 

 the lecture, I suggested to Professor Poulton that the larvae of 

 Odontopera bidentaia would make an excellent subject for further 

 experiments, as I had noticed the great diversity of colour in 

 larvae of this species, when at large, in accordance with the 

 paler or darker appearance of the food they happened to be 

 feeding upon ; and at his request I subsequently sent him some 

 batches of eggs of the species. He told me afterwards that, 

 just as I had anticipated, the results were among the most 

 remarkable he had yet had. 



A striking instance of protective mimicry in this group is 

 afforded by the fine larva of Boarmia roboraria. Several 

 years ago I had a brood hibernating, and which on being shewn 

 to a friend, he was quite unable to distinguish from the oak 

 twigs about which they were resting, so perfect an imitation 

 were they. Every excrescence on the twig, the bud at the 

 top being exactly counterfeited by the swollen head, together 

 with an exact similarity in colour, were apparent. The 

 species is in fact about the most perfect example of mimetic 

 resemblance I know among larvae, and its necessity for the 

 preservation of the species is obvious. It belongs to the 

 group which hibernate as larvas, and spends all the winter 

 motionless and perfectly exposed on a leafless oak, a twig 

 being grasped by the claspers, and the body stretched out 

 sideways, imitating in every detail a short side shoot, and 

 consequently safe probably even from the sharp eyes of a greedy 

 tom-tit. Other illustrations will at once occur to everyone 

 familiar with the subject. Larvae of the 'Pepper moth,' 

 Amphydasis betidaria, a general tree feeder, are green, grey, 

 brown or black, just in accordance with the tree on which they 

 are feeding, wonderfully like the twigs of whatever tree they 

 favour, even the tips being deceptively reproduced in the deeply 

 notched head. A similar case occurs in the long tapering 



