RELATION TO THE HOUSEHOLD 245 



it may be necessary to change the location or even the 

 character of the traps several times; but, faithfully car- 

 ried out, I have never known this plan to fail, and I have 

 personally employed it in two houses occupied by me, 

 when the insects threatened my collection and ate the 

 fresh specimens on the setting boards when not protected 

 by carbolic acid belts. This plan is of no avail against 

 those ants that come in merely as foragers from the out- 

 side, like the black carpenter ants already referred to. 



Of recent years a species of ant has been introduced 

 into one of the southern states from Argentina that is 

 far more troublesome than any of our American species. 

 It bids fair to spread and to become a first class pest so 

 far as it extends; indeed it has been already reported 

 from California and may be more wide-spread than we 

 now believe. It is known as Iridomyrmex humilis, and 

 is as ready to establish its colonies indoors as out. 

 It is under investigation by the entomologists in that 

 section of the country and we may hope that before it 

 gets much further, efficient methods for its control will 

 have been developed. 



In the order Diptera there are no species that are to 

 be considered as guests except the common house-fly, 

 and that is dealt with in the previous chapter in its 

 relation as a carrier of disease. So the flea, which gets 

 into houses not infrequently, does so as a parasite of 

 the dog or cat, and not because of any love for man 

 himself. Other flies there are in the house not infre- 

 quently, but in most cases as scavengers, when at- 

 tracted by decaying or fermenting material, hence not 

 strictly to be dealt with here. To be sure we have 

 "skippers" occasionally, in cheese, especially of -the 

 odorous sorts, and sometimes in bacon and other fat; 

 but they come very decently under the classification of 

 scavengers and need not be further considered here. 



