NO. 7 



PROTECTIVE ADAPTATIONS — McATEE 



139 



of the macrofauna of the lake and about that proportion of the total 

 diet of the fishes. 



Some of the above remarks tending to emphasize feeding on pro- 

 tected forms are special pleading because their authors felt under the 

 necessity of proving " protected " insects do have enemies. The 

 various groups of predators thus referred to, however, prey upon 

 other than the specially protected insects, just as birds do. and ex- 

 amined in that light, the comment " indiscriminate " would in most 

 cases fit their food habits. An adaptation of Poulton's tabulation for 

 robber flies illustrates the point. 



Number 

 Name of prey of records 



Ortlioptera 13 



Rliynchota 12 



Neuropteroidea 7 



Lepidoptera 32 



Coleoptera 40 



Diptera 57 



Hymenoptera 67 



This does not look very ditTerent from tabulations for birds, and 

 clearly illustrates the same propensity demonstrated for that class, 

 namely of preying largely upon the groups most numerous in species, 

 and presumably therefore in individuals — in other words upon what 

 is most available. 



That availability does largely govern choice of food is the very 

 thing that creates problems in wild life economics. When man invades 

 the domain of wild life and in the various phases of his husbandry 

 makes available large supj^lies of new foods, they are immediately 

 attacked and up to a certain limit the enemies steadily increase in 

 variety and abundance. It is needless to cite examples of this imi- 

 vcrsal phenomenon from the vegetable kingdom. All may not realize, 

 however, that it prevails also in the animal world. The temerity of 

 the pioneer estal)lishing an orchard in a clearing in the foothills where 

 the crop is largely harvested by wild life, is paralleled by that of the 

 sheep raiser who grazes his herds in mountain meadows where they 

 are attacked at once by wolves, coyotes, wild cats. l)ears, and other 

 predators. Alan's taking the domestic fowl wherever he goes furnishes 

 material for further demonstration of the supreme influence of 

 availability. The chicken, a native of Asia should have no " natural 



