142 THE WOKLD OF LIFE 



vegetables, and even the grass on our lawns, are in some sea- 

 sons destroyed bj swarms of wire-worms which feed on their 

 roots. Turnips, radishes, and allied plants are attacked by 

 the turnip-fly, a small jumping beetle whose larva lives in the 

 leaf itself, and w^hich often swarms in millions. Then there 

 are the a2:>hides and froghoppers on our roses and other shrubs 

 or flowers, and grubs which attack our apples, our carrots, 

 and most other crops; and all these the gardener usually re- 

 gards under the general term " blight," as a serious blot on 

 the face of nature, and wonders why such harmful creatures 

 were permitted to exist. 



Most professional gardeners would be rather surprised to 

 hear that all these insect-pests are an essential part of the world 

 of life ; that their destruction would be disastrous ; and that 

 without them some of the most beautiful and enjoyable of the 

 living things around us would be either seriously diminished 

 in numbers or totally destroyed. He might also be informed 

 that he himself is a chief cause of the very evil he complains 

 of, because, by growing the plants the insect-pests feed upon 

 in large quantities, he provides for them a superabundance of 

 food, and enables them to increase much more rapidly than 

 they would do under natural conditions. 



Let us now consider what happens over our whole country 

 in each recurring spring. At that delightful season our gar- 

 dens and hedgerows, our orchards, woods, and copses are 

 thronged with feathered songsters, resident and migratory, en- 

 gaged every hour of the day in building their nests, hatching 

 their eggs, or feeding and guarding their helpless offspring. 

 A considerable proportion of these — thrushes, warblers, tits, 

 finches, and many others — are so prolific that they have two 

 or three, sometimes even more, families every year, so that 

 the young birds reared annually by each pair varies from four 

 or five up to ten or twenty, or even more. 



Now, when we consider that the parents of these, to the 

 number of perhaps fifty species or more, are all common birds, 

 which exist in our islands in numbers amounting to many 



