Insect Enemies and Allies 213 



plants much as the biting insects do, and they can be 

 killed with a poison spray. Plants may also be protected 

 from them by a line of powdered lime such as is used to 

 mark a tennis court; they cannot go through it. Salt 

 sprinkled on a slug will cause it to shrivel and die almost 

 instantly. 



Though the earthworm resembles the larvae of some The earth- 

 insects, it is a very different creature. Like some of worm 

 the insects, it is an ally of the farmer. It improves 

 the soil. The scientist Darwin calls it " the great plow- How it im- 



man of the world." In making its way through the p s ^ es ihe 



soil, it swallows earth, which it ejects at the surface. 



The passageways that it makes allow air to enter the 



soil more freely and aid drainage. The earthworm 



lives partly on organic matter that is mixed with the 



earth that it swallows. At night it comes to the sur- 



face and feeds on very small fragments of leaves and 



stems. It finds these near the mouth of its burrow, 



in which it keeps its tail anchored while feeding. If it 



left its burrow completely, it might never find its way 



back, for it is unable to see. 



Honey bees. One of the insects most worthy of The ways 

 study, both oh account of its interesting habits and its f bees 

 usefulness to man, is the honey bee. If people realized 

 how simple a thing it is to care for bees and how profit- 

 able they are, the family beehive might become as com- 

 mon as the family cow. But bees are important not only 

 as producers of honey; as carriers of pollen they 

 cause the fertilization of many flowers, and some plants 

 depend on them alone for this service. 



To study the habits of bees an " observation hive, " 



