MYRIOPODA 377 



but when thousands upon thousands of the Httle insects are in- 

 cessantly sucking away, we can well understand how easily they 

 weaken, and even kill, large and strong plants. 



One kind of aphis has a very remarkable beak. This insect 

 lives on the young shoots of larch-trees, and comes out early in 

 the spring, when there is no foliage on the branches to shelter 

 it from the fierce winds. If it had to trust to its slender limbs 

 for a hold, it would be blown away, and would die. So Nature, 

 instead of giving it a straight beak, has provided it with one 

 shaped like a corkscrew. This, when driven deeply into the bark, 

 gives a very firm hold; and thus the aphis is anchored down, as 

 it were, by its own beak. 



It is not only by taking their sap that the aphis weakens the 

 plants on which it feeds. If you examine its back you will see two 

 tiny tubes projecting, one upon either side. The sap, as it passes 

 through the body of the aphis, is turned into sugar, and comes out 

 through these little tubes. 



This sugar falls upon the leaves below, and makes them as 

 sticky as if they had been smeared with treacle. Now a plant 

 breathes through its leaves, in which there are numbers of little 

 holes for the air to pass in and out. And as the sugar chokes up 

 these holes, it prevents the plant from breathing, and so helps to 

 weaken it. 



This sugar is called "honey-dew''. It is this that the ants are 

 said to extract from the aphis, much as we obtain milk from cows. 

 Owing to this curious habit, the aphis is sometimes known as the 

 "ant-cow". 



MYRIOPODA 



It is perhaps difficult to realize that " centipedes " and " milli- 

 pedes", which form the great class of the MYRIOPODA (the "many- 

 footed "), should be the near relatives of insects, and so come 

 next in order to them. But naturalists now place them in this 

 position, and make the centipedes a class by themselves under 



