The Magpie-Moth, 



405 



warning coloration there is no m^'stery about it so exposing itself. It has been found 

 by numerous experiments with birds, lizards, and monkeys in captivity to be 

 objectionable as food, and the Insect acts as though conscious of the fact, freely 

 exposing itself. 



It is one of the family of geometers, to which we have already referred ; and 

 it is usual throughout that family for the caterpillars to be coloured in harmony 

 either with the foliage upon which they feed or with the branches upon which they 

 rest, and of which they appear to be twigs. The chrysalids, too, are hidden away 

 among dead leaves on the ground, or spun up between leaves on the food-plant. 

 The moths themselves are so cryptically coloured that when they settle on tree- 

 trunks, etc., they are lost am.id their surroundings. In the case of the magpie- 

 moth there are none of these aids, because the Insect being objectionable in all 

 its stages and not sought for as food, there is no chance of protective resemblances 

 being developed. We have said that it 

 is the rule for geometer-moths to be 

 protected by such devices : the magpie 

 is an exception that really does prove the 

 rule. Like the tiger-moth, it N'arics to 

 an extraordinary degree in a state of 

 nature. The other members of the 

 familv v^YV considerably in the breed- 

 ing cages of the entomologist, but such 

 variations are seldom found in the 

 collecting net. It is not that they do not 

 occur in the wild state, but when they 

 do, if the variation is at all in the 

 direction of rendering the Insect more 

 conspicuous, that individual will be 

 snapped up bv an enemv and have no 

 chance of perpetuating the \'ariation. 

 Such is the working of natural selection : 

 alwa3's tending to fix and perpetuate 

 variations that tend to the good of the species by weeding out variations in the 

 other direction. In the case of the magpie-moth, varieties, so long as they retain 

 their warning colours — which arc well understood by insectivorous creatures as an 

 advertisement of inedibility — can perpetuate the varying tendency, because the 

 particular arrangement of their colours is of no moment. So long as they retain 

 the black, white, and yellow they are equallv protected. If any varieties were to 

 appear that lacked these warning colours, though the moths were still inedible, 

 they would surely get killed off or so maimed as to be unlikely to leave descendants. 



The young caterpillars may be found in August, but are not then very notice- 

 able on account of their small size. After feeding for two or three weeks, they 

 retire from public \-iew by spinning up the edges of a leaf and hiding within it. 

 When the leaves fall in autumn that particular leaf does not go with the others, 

 because it has been attached to its twig bv a few threads, and in this cradle the 



Pliutu by J 



Eggs of the j\Iagpie-Moth. 



These eggs were laid in captivity. In a state of nature the female 

 magpie-moth lays her eggs singly, and is careful to deposit one only 

 on each leaf. Thev hatch in a few davs. 



