102 



would l)ocome an ideal mosquito- breeding* place as soon as the oil has 

 ))een sufficiently diluted or carried off. 



Personally I do not like the smell of petroleum, althoug"h I have 

 worked with and recommended its use often enough, and I do not like 

 the scum tmd tarry sediment on the plants and borders of pool or pond. 

 Hence, I do not like that feature of the phinotas oil that makes for a 

 surface coating. It is not at all necessary to help the action of the 

 soluble portion, and it is just as liable to become imperfect as the fuel 

 oil, which costs about one-fourth as much and acts only from the 

 surface. 



Its field is wherever it is desirable to clear any liquid of mosquito 

 larvffi promptly and without regard to conseqences. It is quite pos- 

 si])le that some of the objectionable features would disappear or become 

 materially lessened if no more than enough to obtain the desired result 

 was used; but I w^ould always advise against the use of any poisonous 

 substance in any body of water that contains fish. 



A limitation to the material is that it does not do well, if at all, in 

 salt water. During July I tried it at Anglesea in ))reeding jars and 

 in salt-water pools filled with larvi^ of C. soUicitans. In neither case did 

 it produce the characteristic milky appearance, although used rather 

 in excess, and in the case of the pools there was none of that surface 

 spread which is usually so characteristic. 



These salt-water pools, treated at several places along the shore, 

 proved rather unsatisfactory subjects, and usuall}' I could find, twenty- 

 four hours after treatment, nearly as many larvaj as there were the 

 day before. 



Some of the more promising materials were also used on outdoor 

 pools, but no results difl'ercnt from those of the laboratory were 

 obtained. 



"phinotas disinfp:ctant 20 per cent." 



A sample of material labeled as above was reduced to a 1 to 100 

 stock solution, and two jars, each containing 500 cc of water, were 

 stocked with larvjv of Culesc and Anoj^helen. 



Jar No. 1 receiv^ed 5 cc of the stock at 4.45 p. m., and ten minutes 

 later most of the Culex larv» were dead. At 5.30 p. m. all pup^i?, all 

 Anoylieles larva?, and a few full-grown Cule.r larva> were yet alive. 

 At 8 a. m. next day two Anopheles larvte and .some pupje were 3^et 

 alive. At 12 m. only pupte remained alive, and the record had not 

 changed at 4 p. m., when the experiment was closed. 



Jar No. 2 received 10 cc of the stock at 4.45 p. m., and ten minutes 

 later nearly all Cule,v and the smaller Aiwpheles larvae were dead. At 

 5.30 p. m. one or two Culex larvj^ were yet feebly alive. At 8 a. m. 

 next da}' several Anopheles larvte and several pup;e were yet alive, 

 though all larva? were dead. No adults emerged in either jar. 



