The Two-winged Flies 357 



^^•ill keep them dcnvn. Mats and places where dogs and cats lie down should 

 be kept well dusted with pyrethrum. (Buhach is the trade name for this 

 insecticide, which is not injurious to man or domestic animals.) Where 

 fleas get a foothold in a neglected room or cellar, the remedy used by Profes- 

 sor Gage in the basement of one of Cornell University's buildings might be 

 tried; i.e., tying sheets of sticky fly-paper, sticky side out, around the legs 

 from foot to knee of the janitor or a cheap boy and having him tramp for 

 several hours around in the room! 



Of the various other flea species, the only ones that come into special 

 relation with man are the rat-fleas. The proof that rats are active agents 

 in the dissemination of the dreadful bubonic plague, and the belief of some 

 pathologists that the disease-germs may be transmitted from rats to man 

 by the bites or punctures of rat-fleas, gives this insect a special interest like 

 that attaching to the malaria- and j-ellow-fever-dissminating mosquito and 

 the germ-carrying house-fly. Baker pertinently calls attention to the fact 

 that the rat-fleas of this country are only remotely related to Piilex irritans 

 and Clenocepltalus ranis, the two species that bite human beings, while the 

 fleas that infest rats in the tropics are, on the contrary, very nearly related to 

 the man-infesting kinds. The prevalence of the bubonic plague in tropical 

 countries and its rarity with us may be connected with this difi'erence in the 

 rat-flea kinds. 



