172 . THE COLOUKS OF ANIMALS 



clear in this and parallel cases ; for when many indi- 

 viduals combine to discharge an unpleasant odour, 

 they become surrounded by an atmosphere which acts 

 as a most effective barrier. 



Irritating hairs possessed by certain larvsB 



Again, caterpillars may be protected by possessing 

 irritating hairs. This is the case with the ' Palmer 

 worms ' mentioned above, which are thus doubly pro- 

 tected. Many people have discovered this fact to 

 their cost after handling these pretty black, red, and 

 white caterpillars, which are so abundant and freely 

 exposed on our hawthorn hedges in early summer. 

 When the face or neck is touched by the hands, which 

 are covered with minute barbed hairs shed by the 

 caterpillar, an intensely irritating rash soon makes its 

 appearance. The same effect is produced, as I shall 

 always remember, if an old cocoon, in which the hairs 

 are interwoven, be pulled to pieces with the fingers. 

 These caterpillars were nearly always refused, but Mr. 

 Butler records that they were in one case eaten with- 

 out hesitation by a young sky-lark, which soon after- 

 wards died with symptoms which may have been due 

 to the irritating hairs. One of my lizards also seized 

 a larva, but relinquished it after biting it for sometime. 

 The lizard was evidently greatly irritated by the hairs 

 in its mouth. Many other hairy caterpillars also 

 produce a rash : thus, the larvae of the Fox Moth 



