NATURAL ENEMIES 85 



is true that the larvae of certain Carabseid beetles, and 

 especially those of the genera Harpalus, Platynus and 

 Agonoderus, are sometimes found frequenting manure 

 and feeding upon young fly larvae, and that certain 

 rove beetles and their larvae, of the family Staphylinidae, 

 are also found in the same situations, engaged in the 

 same task. And Packard (1874) records the finding 

 of a beetle pupa in the puparium of the house fly. But 

 one would think that a pile of horse manure swarming 

 with fly larvae would attract hordes of predatory beetles 

 and of pirate bugs and the like. Is it that house fly 

 maggots are distasteful to these voracious creatures? 

 Or is their perception of odors keen and are the am- 

 moniacal odors of the manure pile repugnant? It is 

 difficult to say. The typhoid fly belongs plainly to a 

 most persistent type, and it feeds freely and abundantly 

 in close proximity to many insects which we would 

 naturally suppose to be its enemies. 



But we must not forget the ants. It is true that 

 many ants are nuisances, and in the case of the destruc- 

 tion of the typhoid fly by ants we have simply one nui- 

 sance multiplying at the expense of another, but Forel 

 and Wheeler admit that as a group ants are beneficial 

 and that many species deserve our protection. Capt. 

 P. L. Jones of the U. S. Army Medical Corps (quoted 

 by Garrison, U. S. Naval Med. Bull, Oct., 1910, p. 

 551) made certain experiments in the Philippines to 

 determine whether the scarcity of flies in those islands 

 was due to some epidemic disease. In the course of 

 the experiments it was found impossible to raise flies 



