PROTECTIVE DEVICES. 



FIG. 50. 

 Spiny Caterpillar, the spines poisonous. 



insects. The unpleasant odour of 

 bugs is certainly a protective device ; 

 so too are the bad tasting oils of the 

 blister beetles and ladybird beetles. 

 Some beetle grubs cover themselves 

 in their own excrement, others 

 carry their cast skin. The Lace- 

 wing grub carries a pile of the cast 

 skins of its victims. Stings are 

 probably protective, though birds 

 and lizards eat bees. An unpleasant 

 taste is also probably protective 

 and is associated with the scheme 

 of colouring known as warning 

 colouration. 



Sex also profoundly modifies 

 the structure of insects. The 

 internal organisation is of course 

 totally distinct and there are com- 

 monly external organs which 

 readily reveal the sex (fig. 52). 



FIG. 51. 



The lied Ant, a wingless worker, mature 

 but sexless ; their pungent flavour 

 and keen bite is their protection. 



