158 SOME SUGGESTIONS FOR THE STUDY OF INSECTS. 



noted above, we observe further that they are not easily 

 seen. In the confused light and shade of a currant bush 

 the black and creamy pattern of their skins renders 

 them difficult of observation. One has to look upward to 

 find them, as they occur generally on the under side of the 

 leaves. Keen -eyed birds may see them more readily than 

 the eyes of men do, just as young children 

 will find them quicker than men will. But 

 keen-eyed small birds will not touch them 

 on account of their nauseous taste. The 

 only bird which appears to take them in 

 numbers is the cuckoo (Sparrows attack 

 the adult insects). 



When the caterpillars are fully grown, 



Fig. 50. Leg of -T ji i T JT 



Caterpillar, -6. about the month ot June, they pass 



into the pupa or chrysalis stage. This 

 transformation should be watched in the 

 rearing cages and a description of it written out by pupils. 

 They will note the soft yellowish appearance at first, 

 becoming transformed into the glossy black and gold banded 

 colour in a short time. The pupae should also be figured, 

 and it is important that the pupils should distinguish the 

 chief parts of the body upon it, recognising in particular 

 the wing rudiments, head, thorax, and 

 hind body. . 



What is the significance of these two 'Jjt/ >/\\|i 

 stages? Jv>/l<'v 



Caterpillar Stage. It will have become 

 obvious to the pupils that the life of a Fj g . 57. p ro -ieg O f 

 caterpillar is devoted entirely to feeding, a Caterpillar. 

 with growth as a result. Attention should 

 also be called to the moulting consequent upon growth. 

 Why do caterpillars moult ? What is thrown off when they 

 moult ? The outer layer of their skins. A tough cuticle 

 (composed of the substance chitin), which, being simply a 

 non-living product of the skin, cannot grow. Hence it 

 must from time to time be thrown off from the body 

 growing beneath it. This is the answer to our question 

 why they moult. 



