Methods of Protection 



31:5 



The caterpillars of some Sawflies (fig. 1 71) secrete a 

 dark-coloured slime which envelopes and protects 

 their bodies, giving them the appearance of a small 

 black slug rather than of an insect larva. 



Protection by Form. — The Froghopper-nymph in 

 its frothy covering is soft-skinned and sluggish ; 

 defences, such as we have just been considering, are 

 usually resorted to by insects which are weak and, 

 in many cases, degenerate. Similarly grubs which 

 feed in concealed situations — underground, within 

 plant-tissues, or immersed in refuse — are soft-skinned 

 and defenceless, their food-material providing them 

 with shelter as well as with nourishment. But the 

 Froghopper when fully 

 developed, with a firm 

 chitinised skin, two pairs 

 of wings and powerful 

 jumping legs, is able to 

 live freely and openly on 

 plants, needing no 

 longer the shelter of the 

 frothy "cuckoo-spit," 

 since its activity enables 

 it to escape from its 

 enemies. In the same way the maggot which feeds 

 underground in carrion becomes changed into a 

 strongly-armoured fly or beetle, needing concealment 

 and shelter no longer, but depending on its swift flight 

 or its quick running for success in the battle of life. 

 The protection afforded to active insects by every 

 feature of their outward form — their hard skin, their 

 spiny processes, their bristles and hairs, their perfect 

 sense-organs and their powers of motion — is too 

 obvious to need comment. 



Protective Resemblance. — But many Insects are 

 protected in a special way by their form in conjunction 



. 171. — -. _; ~_ -;. -^'10- 



campoidis umacina. Scop.), alter cast- 

 ing dark slime-covered skin (a.). 



