INSECTS AND OTHER ORGANISMS 397 



finally penetrate to the outside the filaments that give rise 

 to the spores (conidia) that are set free by thousands and 

 millions. The elongate, conspicuous fructifications of fungi 

 of the genus Cordyceps growing out of the bodies of cater- 

 pillars infected or killed by those organisms are among the 

 well-known '* curiosities " of insect relationships. 



Insects are of great importance as a source of food- 

 supply to predaceous animals of diverse kinds. Spiders 

 of various families, differing in structure and habit, 

 stalk-insects as they feed on plants, pursue and run 

 them down in fair chase, leap suddenly from their lairs 

 on unseeing insect victims, or set silken snares which 

 appear cunningly woven to catch the feet of flies. Many 

 aquatic insect larvae serve as food for fishes ; mayfly are 

 devoured in myriads at the season of their emergence by 

 trout. Birds of many families take insects as their staple 

 food at least during part of the year, rapid fliers like the 

 swallows, martins, and swifts, seizing small insects on the 

 wing as they swoop through the air, while such birds as 

 tits, wagtails, and warblers search diligently for caterpillars 

 feeding on plants or for aphids and scales sucking sap. 

 Wading birds take toll of marsh-feeding grubs ; rooks and 

 gulls eat voraciously the root-feeding larvae of the soil. 

 Even mammals do not all disdain insects as food. The 

 American ant-eaters and the African and Oriental pangolins 

 break into ants' nests and with their long tongues lick up 

 the inmates. Bears raid the nests of wild bees for honey, 

 and the badger of our own countryside often digs out 

 wasps' nests (Plate VIII, B) and makes a good meal on the 

 succulent grubs. 



We must now consider a few of the immense number of 

 examples of special life-relations which may be observed 

 between insects and other animals. Many of these, directly 

 bearing on methods of obtaining food, and on the comrade- 

 ship between societies of insects and '* guests," whether 

 insects of diverse kinds or orders, or animals of other groups, 

 have been described in previous chapters (pp. 248-52, 

 259-60). Here it may suffice to notice examples of insects 



