214 



THE FOOD OF ANIMALS 



is known as to their habits, but they are supposed to feed on 

 disintegrating vegetable and animal matter. A good example is 

 the shining Silver-Fish i^Lepisma saccharind) with long antennae, 

 and three jointed filaments projecting from its tail end. It is 

 found in brown sugar, and among starchy substances. In one 

 section of the order, the Spring-Tails, there is a sort of elastic 

 fork, which can be bent under the body and then liberated so as 

 to enable the creature to leap into the air. One of the most 

 curious of these species is the so-called Glacier- Flea {Desoria 

 glacialis), often found on the surface of ice or snow in Alpine 

 regions. 



Those plant-feeding insects now fall to be considered in which 

 the mouth-parts are more or less perfectly suctorial. 



SCALE-WINGED INSECTS (Lepidoptera) 



This order consists of the Butterflies and Moths, which are 

 nearly all plant-feeders. The voracious larvae, commonly known 

 as " caterpillars ", play havoc with all sorts of vegetation, and 

 the most important mouth-parts which they possess are large 

 biting mandibles, so that in this respect they differ widely from 

 the adult. The way in which the larvae feed by biting away 

 pieces of leaf can be observed in almost any kitchen-garden, a 

 notable case being that of the green caterpillars of the Cabbage 

 White (Pieris brassicce), which in some years appear in almost 



incredible numbers. 

 The larvae of the 

 Silk Moth {Boinbyx 

 mori), commonly 

 called ' ' silkworms ", 

 furnish another 



readily accessible 

 instance. Many 



adult butterflies and 

 moths feed but little 

 or even not at all, 

 but those that do and those that do not feed alike possess an 

 elaborate suctorial proboscis, adapted solely for taking in liquid 

 nourishment, generally consisting of the nectar secreted by 

 flowers. This organ consists (fig. 446) of the two much-elon- 

 gated Jirst maxillcB, each of which is in the form of a half-tube, 



Fig. 446.— Heads of Butterflies (enlarged to show proboscis] 



