LARVICIDES 379 



What seems an excellent idea, and which can be put in practice under certain 

 conditions, in the way of catching adult mosquitoes, was described in the Mont- 

 clair (N. J.) Herald of July 29, 1910, in which it is stated that Mr. John T. 

 Lyman, of 183 Cooper Avenue, Upper Montclair, has a small vacuum carpet 

 cleaner which is run by the electric current obtained by removing an electric light 

 bulb and connecting the motor of the cleaner to the socket. Just before retir- 

 ing, it is said, Mr. Lyman runs the cleaner over the walls of the sleeping room, 

 not allowing it to touch the walls, but keeping it at a distance of several inches ; 

 the result is that every mosquito, fly or other insect resting upon the walls is 

 sucked into the dust bag at the lower end of the machine. This work, it is said, 

 is accomplished in two minutes to each room, and Mr, Lyman and his family 

 retire to rest undisturbed. 



A similar apparatus was used in the spring of 1910 by Dr. E. F. Phillips, of 

 the Bureau of Entomology, against the house fly. He found that by using a 

 nozzle with a fairly wide opening, such as is used in cleaning carpets, the flies 

 were sucked in quickly and almost always before they could make an effort to 

 escape. Doctor Phillips states that when the flies get into the dust-bag there is 

 no chance for escape as they are covered with dust and soon die. 



DESTRUCTION OF LARV/E. 



In considering the destruction of larvae we will first take up those measures 

 which involve the use of what have come during recent years to be termed 

 " larvicides." The dictionary definition of the word insecticide is " One who or 

 that which kills insects, as insect powder"; therefore, a definition of larvicide 

 would be one who or that which kills larvse. But in mosquito work it has come 

 to be applied to those substances which are applied to bodies of water in which 

 mosquito larvse are living, and which results in their destruction in one way or 

 another. These substances, for the most part, are either poisons or more fre- 

 quently oils which, forming a surface film, destroy the larvae when they come to 

 the surface tc breathe. Ronald Eoss long ago pointed out the great desideratum 

 in this direction in the following words : " I have long wished to find an ideal 

 poison for mosquito larvae. It should be some solid substance or powder which 

 is cheap, which dissolves very slowly, and which, when in weak solution, destroys 

 larvae without being capable of injuring higher animals. What a boon it would 

 be if we could keep the surface of a whole pond free from larvae simply by 

 scattering a cheap powder over it, once in six months or so. It is very possible 

 that such a substance exists, but unfortunately we have not yet discovered it." 

 (Mosquito Brigades, London, 1902, pp. 33 to 34.) 



A great many experiments have been tried with poisonous substances in the 

 search for the desideratum described by Dr. Ross, but although it is now seven 

 years since he wrote this paragraph we still have not discovered it. As early as 

 1899 Celli and Casagrandi published an account of an elaborate series of labora- 

 tory experiments on the destruction of mosquitoes by various chemicals in a 

 paper entitled " La Distruzione delle Zanzare," published in the Annali d'Igiene 

 Sperimentale. These experiments resulted in little practical good, and one of 



