105 



disinfectant into 50 g-allons of water, stir thoroughly and apply to 

 pools and gutters with a sprinkler. Sewer catch basins were not 

 treated because it was not realized until late in the season how many 

 of the insects bred in such places. 



"I'UKALINE." 



This is a preparation similar to the preceding, but nmch cheaper, 

 and is also used as a disinfectant. It dissolves in water in the same 

 way and produces a milky mixture. Cresol is the active base. 



Several mixtures more dilute than 1 to 10,000 were tried, and 

 proved practically ineffective. Larvse and pupa3 of Oulex pungens 

 only were used. The effective mixtures were as follows: 



To jar No. 1 I added from the stock solution enough to make the 

 proportion 1 to 8,000. An hour afterwards a few larva? and all pupte 

 were yet alive, but next morning everything was dead. 



Jar No. 2 received stock solution to make the mixture 1 to 1,000, 

 and an hour afterwards all larvas and nearly all pupte were dead. 



At 1 to 1,000 this material is as effective against mosquitos as the 

 chloro-napthalum is at 1 to 1,000 — that is, four times as effective at 

 one-fourth the price. Its range of usefulness is as for the previous 

 mixture. 



"tarola." 



This preparation is from the Barrett Manufacturing Company; is 

 also soluble in water, and produces a milky emulsion. 



The usual 1 to 100 stock was made, and 5 cc was added to 500 cc of 

 water containing larvae and pupag of Culex and Anopheles^ at 10.10 

 a. m. An hour later most of the Oulex larvse were dead. At 3.15 

 p. m. a few more pupse were dead. Next day at S a. m. no more pup^e 

 had died, and I added 10 cc from the stock, making the mixture 1 to 

 2,500; but at 11 a. m. many pupae were yet alive. 



The remarkable resistance of the pupte to preparations of this char- 

 acter is quite noticeable, and at 1 to 2,500 it was not really more 

 effective than at 1 to 5,000. 



' ' MILKY DISINFECTANT. " 



This is another of the preparations of the Barrett Manufacturing 

 Company, and produces the same milky emulsion. 



The usual 1 to 100 stock was prepared, aitd at 8 a. m. 5 cc was added 

 to 500 cc of water containing larvtB and pupte of Anoplieles and Ctilex. 

 An hour later all the larvaj were dead. At 10.30, as no pupas were 

 dying, 1 added 5 cc from the stock solution. At 3.15 p. m., no change 

 being noted, I added 5 cc additional from the stock, and at 5.45 p. m. 

 a few pupffi were dead. At 8 a. m. of the day following some pupae 



