232 INSECT TRANSFORMATION 



becomes more or less formidably armoured. Caterpillars of 

 the "tussock' family (Lymantriidae) , to which belongs the 

 Brown-tail moth, just mentioned, have tufts of long barbed 

 bristles which if incautiously handled, work their way 

 into the skin causing severe irritation and sores. There 

 is much evidence that such hairy and spiny caterpillars are 

 not eaten by insectivorous birds, which devour readily com- 

 paratively smooth larvae like those of owl-moths. This hairy 

 clothing is thus a valuable protection and it is probably 

 advantageous also when the species winters in the larval 

 condition, as is the habit of the Brown-tail and of our common 

 Garden Tiger moth (Arctia caia). Some of these hairy cater- 

 pillars are active in habit and comparatively rapid in move- 

 ment ; the brightly coloured " tussock " larvae of our common 

 Vapourer moth (Orgyia antiqua), for example, often migrate 

 from tree to tree across considerable tracts of country, a habit 

 valuable for extending the range of a species whose wingless 

 adult female never feeds, and never moves away from the 

 cocoon whence she emerged. In the earlier stages of their 

 growth, such hairy caterpillars are often carried long distances 

 by the wind. Often hairiness in caterpillars is associated with 

 bright and strongly contrasted colours; 1 the "Vapourer' 

 larva, for example, is adorned with tufts of yellow, black and 

 red, the " Lackey" displays a livery of longitudinal stripes of 

 red and blue, the " Bufftip " is striped black and yellow. 

 There is a considerable mass of evidence, that such conspicuous 

 types of coloration among animals are associated with some 

 noxious or distasteful quality, and insects thus adorned are 

 commonly refused by insectivorous birds. Hence has arisen 

 the general belief that these " warning " colours are advan- 

 tageous to their possessors, since they serve to advertise 

 inedibility, and are easily recognized by insectivorous animals, 

 which quickly learn by experience to leave conspicuously 

 coloured creatures unmolested. Such " warning ' colours 

 are seen also in many caterpillars with comparatively smooth 

 cuticle such as the " Cinnabar " (Hypocrita jacobaeae], with 



1 E. B. Poulton : " The Colours of Animals ". London, 1890. 

 " Natural Selection the Cause of Mimetic Resemblance and Common 

 Warning Colours ". Joiirn. Linn. Soc. Zool., XXVI. 1898. G. A. K. 

 Marshall and E. B. Poulton, " Observations and Experiments on the 

 Bionomics of South African Insects ". Trans. Entotti. Soc., London. 1902 . 



