91^ 



THE NATURE BOOK 



THECLA QUERCUS, MALE AND FEMALE FROM ABOVE AND BELOW. 



once apparent to thcise who have ex- 

 perienced the dehghts of a collecting 

 ramble on the seashore. 



The colour of the caterpillar is brown, 

 sometimes tinged slightly with green or 

 pink. Its back is very convex, and down 

 the middle there is a kind of groove, 

 darker in colour. Down the back runs 

 a chain of markings, somewhat arrow- 

 shaped, and pale brownish or pinkish in 

 colour. It is not always an easy matter 

 to describe in words the appearance of 

 an insect in such a way that the reader 

 will be able to recognise it at sight. In 

 this instance, however, I feel justified in 

 comparing the caterpillar, and its colour- 

 ing, with the crumpled bud-scales of the 

 oak which, in June, still remain at the 

 bases of the petioles of the leaves. I 

 have been so much impressed by this 

 resemblance on many occasions that I 

 cannot help thinking it must be another 

 instance of " protective colcmring." 



It is easy to imagine that a hungry 

 bird, peering among the oak foliage, 

 might mistake this caterpillar for a little 

 bundle of dry and worthless bud-scales. 



When it has finished its feeding, the 

 Purple Hairstreak caterpillar assumes its 

 pupal form. As the time for the change 

 ap])r()aches, the insect loses most of its 

 colour and becomes bU^ated and sluggish. 

 After lying in this state for some hours, 

 practically without stirring, it commences 

 a series of rh\1:hmic movements — the 

 muscles of its body seeming to rise in 



waves from its head to its tail. By this 

 means its skin is gradually worked back- 

 wards, in much the same way as one works 

 a glove on to the fingers of one's hand. 

 Eventually, the skin immediately behind 

 the head splits, and the pupa begins 

 to emerge. The rhythmic movements 

 continue, and in a few seconds more the 

 whole larval skin is completely worked 

 off. At first the pupa is white, slightly 

 tinged with pink, while it is about the 

 same length as was the caterpillar. But 

 it rapidly contracts, becoming ultimately 

 stout and rounded. Its colour, too, 

 soon darkens to deep reddish brown. 



The foregoing remarks apply to the 

 change from caterpillar to chrysahs as 

 it takes place when the insect is in cap- 

 tivity, either upon the floor of the breeding 

 cage or just beneath the surface of earth 

 should this have been provided. For 

 when in capti\'ity this caterpillar does 

 not spin any silk pad for its anal hooks, 

 or fasten itself by means of a silk belt, 

 after the common custom of its kind. 

 Moreover, there is no doubt that the 

 Purple Hairstreak caterpillar, even in its 

 wild state, often pupates in the mould or 

 moss at the foot of its tree trunk. But 

 several authorities agree in stating that 

 the pupa is normally suspended from an 

 oak-leaf by the anal extremit\' and girded 

 in the orthodox manner. The writer, 

 however, has ne\'er yet been able to 

 discover it in this position. 



I have already said that the perfect 



