74 PREVENTIVE AND REMEDIAL WORK AGAINST MOSQUITOES. 



larvae. A number of these have been brought or sent to the writer 

 for experimentation, but, considering the cost, none of them has 

 been of as great practical value as petroleum. In his report on the 

 mosquitoes occurring in the State of New Jersey, Dr. John B. Smith 

 describes a number of experiments with substances of this kind, nota- 

 bly with certain soluble carbolic acid and cresol preparations, with 

 chloro-naphtholeum, and with phinotas oil, and in his report for 1907 

 he gives the results of certain experiments with a substance known 

 as "killarvse." It is not necessary, however, to consider any of these 

 substances in this connection except to state that phinotas oil has 

 met with considerable use, since it forms a milky compound with water 

 which settles through a pool and destroys not only mosquito larvae, 

 but all other animal life in the pool. It is used in cesspools and recep- 

 tacles of that kind, and is also found to be of service in the anti- 

 mosquito work on the Isthmus of Panama. 



In another section we have spoken of the use of certain aquatic 

 plants as forming so dense a covering over the surface of the water 

 as to exclude mosquito larvae from access to air, thus bringing about 

 their destruction. Another method which brings about the same 

 results, although in a different way, is described by Consul Wm. H. 

 Bishop, of Palermo, Sicily, in the Monthly Consular and Trade 

 Reports, No. 331, April, 1908, in which he quotes from an account 

 of the experiments made by the chief of the sanitary service at 

 Gaboon, French Africa, with cactus as a substitute for petroleum 

 in the extermination of mosquitoes in warm climates. Beyond this 

 account by Mr. Bishop we have no further information of this remedy: 



The thick, pulpy leaves of the cactus, cut up in pieces, are thrown into water and 

 macerated until a sticky paste is formed. This paste is spread upon the surface of 

 stagnant water, and forms an isolating layer which prevents the larvae of the mosqui- 

 toes from coming to the top to breathe and destroys them through asphyxiation. It is 

 true that petroleum can do the same service, but in warm climates petroleum evapo- 

 rates too quickly and is thus of little avail. The mucilaginous cactus paste, on the 

 contrary, can hold its place indefinitely, lasting weeks, months, or even an entire year; 

 and the period of the development of the larvae being but about a fortnight it has the 

 most thorough effect. 



After all we are practically reduced to the use of oils in this kind of 

 work. Some effort has been made to find if there are any other oils 

 that could be used to better advantage than petroleum. A suggestion 

 was once made by Mr. W. J. Matheson that corn oil might be used. 

 This is a substance which is made rather extensively in certain parts 

 of the country and which, considering the enormous crops of corn 

 grown in Western States, which in fact are so great that in past years 

 of overproduction corn has been burned as fuel, might reasonably 



° Report of the New Jersey State Agricultural Experiment Station upon the Mos- 

 quitoes Occurring within the State, their Habits, Life History, etc. Trenton, N. J., 

 1904. 



