82 SECTIONAL ADDRESSES. 
to reproduce, with the kind permission of the Entomological Society, two 
plates recently published in the Transactions.” j 
The moth model and butterfly mimic, beautifully illustrated on plate I, 
really speak for themselves ; but it must be explained that the resemblance 
between the patterns is much closer on the upper surface of the wings 
than on the under; that the orange patch evidently becomes a con- 
spicuous warning mark (aposeme) in the position of rest when the insects 
hang with drooping wings and the under side of the body is uppermost ; 
that the position of the mimic’s patch on the parts of the wings which 
cover the body and not on the body itself, as in the model, is evidence 
of selective elimination guided by the sense of sight; also that model and 
mimic fly together round the tops of trees, the former being much the 
commoner. I owe this most interesting example to my kind friend, 
Dr. Karl Jordan, of the Tring Zoological Museum. 
The second example, shown on plate II, is of a very different kind, 
but I think equally interesting and convincing. The oval yellow masses 
of silk spun on the outside of their cocoons by the caterpillars of the W. 
African Bombycid moth, Noraswma kolga, closely resemble the cocoons 
constructed by Braconid parasites which have devoured a larva or pupa. 
The appearance is, I believe, well known to nearly everyone and is 
especially common in the autumn, when the dead or dying caterpillars of 
the Large Garden White butterfly may be seen on walls and fences, 
bearing the yellow cocoons of the parasitic larvee which have destroyed 
them. It has sometimes been thought that the object of the pretended 
Braconid cocoons is to deceive the female Bracen in her search for cater- 
pillars in which to deposit her eggs, but this is most improbable because 
these parasites are guided by other delicate senses in addition to sight, 
which perhaps is not employed for this purpose ; above all, because the 
eggs which are the ultimate cause of parasitic cocoons like the pretended 
ones, would have been laid far back in the life of the victim. It is probable 
that the conspicuous yellow colour is advantageous to the parasites, for 
the small cocoons are very tough and contain but a small amount of food. 
A few experiments, perhaps a single one, would teach a bird that a cocoon 
bearing these yellow masses contains only a shrunken skin, and also that 
the yellow cases themselves are not worth opening. The yellow warning 
colour is advantageous to the parasites ‘ because enemies are all the more 
readily discouraged from making attempts which would incidentally lead 
to the destruction of some of them. Hence the obvious advantages 
conferred by false cocoons of parasites when mistaken for real ones.’ 
This interesting adaptation was discovered ‘by my old friend, Dr. W. A. 
Lamborn, O.B.E., who, a little earlier, had found another example in 
which the same deceptive resemblance was brought about in a totally 
different way. The cocoon of another West African moth (Dezlemera 
antinori) he observed to be covered with little yellowish spheres so very 
like Braconid cocoons that he kept them and watched for the parasites to 
2 Trans. Ent. Soc. Lond., vol. lxxix., 1931, pls. xiv and xv. The cost of reproduc- 
tion has been borne by the Fund for Promoting the Study of Organic and Social 
Evolution, presented to Oxford University by my dear friend Prof. James Mark 
Baldwin. 
23 Trans. Ent. Soc. Lond., vol. lxxix., 1931, p.397. This paper gives full references 
to all the observations here referred to in the description of pls. I and II, as well as 
others necessarily omitted. 
