FIELD NOTES ON BUTTERFLIES 



there is a fine patch of nettles, and on these we shall 

 most likely find a colony of spiny caterpillars busily 

 engaged in devouring the leafage, or perhaps they 

 may be sunning themselves on the web of silk which 

 is the result of their co-operative industry. This web 

 may be regarded as the common hall of the colony, in 

 or upon which they congregate for moulting, basking, 

 or other purposes. If the caterpillars we find are black, 

 speckled with minute white dots, they will produce the 

 peacock butterfly ; or if they are greenish-grey or 

 ochreous grey, with paler lines along the back and 

 sides, then the small tortoiseshell may be expected 

 to result from them. When full-grown such cater- 

 pillars are rather formidable-looking creatures, clad 

 as they are in spiky armour. They may, however, be 

 handled with impunity, as the apparently sharp point 

 of the spines yield to the touch and are incapable of 

 penetrating the skin. The repellant character of this 

 style of caterpillar clothing is effective enough no doubt 

 in the case of birds. It is, however, not efficient in 

 securing immunity from the attack of parasitic flies. 

 Now we will look at those thistles growing on the 

 common where a painted lady butterfly was seen on the 

 wing a week or two ago. Yes ! here are signs of a cater- 

 pillar having fed upon this plant. The fleshy parts of 

 these leaves are completely demolished, but they still 

 remain fastened together by silken threads. A little 



