no 



AFRICAN MIMETIC BUTTERFLIES 



yet without serious injury, after rough treatment that would have proved fatal to a harder 

 but less elastic animal.' 



Wallace, in ' Natural Selection in Tropical Nature ', gives considerable evidence as to 

 the unpalatabihty of many butterflies. In speaking of the Heliconidae he says, ' These 

 beautiful insects possess, however, a strong pungent and semi-aromatic or medicinal odour, 

 which seems to pervade all the juices of their system. When the entomologist squeezes 

 the breast of one of them between his fingers to kill it, a yellow liquid exudes which stains 

 the skin, and the smell of which can only be got rid of by time and repeated washings. Here 

 we have probably the cause of their immunity from attack, since there is a great deal of 

 evidence to show that certain insects are so disgusting to birds that they will under no 

 circumstances touch them. Stainton has observed that a brood of young turkeys greedily 

 devoured all the worthless moths he had amassed in a night's " sugaring ", yet one after 

 another seized and rejected a single white moth which happened to be among them. Young 

 pheasants and partridges, which eat many kinds of caterpillars, seem to have an absolute 

 dread of that of the common currant moth, which they will never touch, and tom-tits, as 

 well as other small birds, appear never to eat the same species. In the case of the Heliconidae, 

 however, we have some direct evidence to the same effect. In the Brazilian forests there 

 are large numbers of insectivorous birds — as jacamars, trogons, and puffbirds — which catch 

 insects on the wing, and that they destroy many butterflies is indicated by the fact that the 

 wings of these insects are often found on the ground where their bodies have been devoured. 

 But among these there are no wings of Heliconidae, while those of the large showy Nym- 

 phalidae, which have a much swifter flight, are often met with. Again, a gentleman who 

 had recently returned from Brazil stated at a meeting of the Entomological Society that 

 he once observed a pair of puffbirds catching butterflies which they brought to their nest 

 to feed their young ; yet during half an hour they never brought one of the Heliconidae, 

 which were flying lazily about in great numbers, and which they could have captured more 

 easily than any others. It was this circumstance that led Mr. Belt to observe them so long, 

 as he could not understand why the most common insects should be altogether passed by.' 



The single white moth above referred to was Spilosoma menthastri. Jenner Weir found 

 that this moth was refused by the bullfinch, chaffinch, yellow-hammer, and reed-bunting, 

 though it was eaten after considerable hesitation by a robin. Amongst beetles the same 

 experimenter found that the common Malacoderms (Telephorus) known as * soldiers and 

 sailors ' were invariably refused by birds. Mr. Weir communicated the results of his exten- 

 sive experiments to the Entomological Society in two papers on the relation between the 

 colour and edibility of Lepidoptera and their larvae (1869 and 1870) . He found that his birds 

 would not eat hairy caterpillars, or any that were highly coloured and conspicuous in their 

 habits, such as those of the Magpie or Currant moths, but that ' all caterpillars whose habits are 

 nocturnal, which are dull coloured, with fleshy bodies and smooth skins, are eaten with 

 the greatest avidity. Every species of green caterpillar is also much relished. All Geometrae 

 whose larvae resemble twigs as they stand out from the plant on their anal prolegs, are 

 invariably eaten '.^ A. G. Butler also contributed, in 1869, a paper entitled 'Remarks upon 

 some Caterpillars which are unpalatable to their Enemies '. Butler's observations con- 

 firmed those of Weir. Lizards and frogs, which would greedily eat caterpillars, flies, and 

 even bees, would not eat the larvae of the Magpie and Burnet moths, and also that of 

 //. wavaria, which they frequently seized but always rejected. Spiders also rejected such 

 larvae. Professor Weismann experimented with lizards and birds and found that they refused 

 1 These generalizations require some modifications in view of the experiments of Professor Poulton and others. 



