101 



larvfe and pupae were dead. This is a hint that if crude oil is to be 

 used it must not be too heavy, but must have light oils enous^h to ena- 

 ble it to spread thinly over the surface. 



PHINOTAS OIL. 



This material has been used in a number of places with excellent 

 success and combines in a remarkable degree the water-poisoning 

 quality like that of the cresol preparations, with the surface-coating 

 ett'ect of the light mineral oils. Dropped into water in a coarse spray 

 it sinks to the bottom in globules which begin to dissolve, giving a 

 milky tinge to the water around each. In a short time these globules 

 rise to the surface, burst, and a surface coating extends in each direc- 

 tion from the center. The question was, how little of the material is 

 needed to produce the effect, and to this end a number of experiments 

 were made at different periods in the summer in fresh water and in 

 salt. Only two laboratory tests need be referred to here. 



I prepared a mother mixture of 5 cc of phinotas oil in 500 cc of 

 water, the ratio being 1 to 100. Of this 1 poured 5 cc into 500 cc 

 of water containing mosquito larvae of all sizes, the strength of 1 to 

 10,000. In 5 minutes all were dead. 



To another jar I added 3 cc of the mother mixture to 500 cc of 

 water (about 1 part in 16,000) and in less than half an hour all the 

 larvae were dead. 



The limit of practical effectiveness may be safely set at 1 part to 

 15,000 of water; that is, 1 gallon of phinotas oil will so jjoison 15,000 

 gallons of water as to kill all mosquito larvte there may be in the 

 water. It is doubtful whether any other material comes anywhere 

 near this in effectiveness. Furthermore, the action of the material is 

 not affected b}^ the wind. It spreads everywhere throughout the 

 water, and if the body be confined it remains poisoned for weeks unless 

 added to materiall}". 



It would seem as if we had here the ideal mosquito destroyer, and 

 so we have for certain purposes. In sewer or catch basins or in foul 

 or stagnant pools it would be almost impossible to find anj^thing bet- 

 ter. In stagnant gutters it is very useful, but the oily surface scum is 

 objectionable. Yet in every well organized mosquito campaign this 

 phinotas oil would seem to be indispensable. 



The objection to the material is that it is too effective in undesired 

 directions, for it kills things that it is not desirable to injure if possible. 

 It is quite probable that it has been used in altogether too large quan- 

 tities; but as used it has killed fish as well as other aquatic animals 

 and insects, and it has been accused of killing chickens and other ani- 

 mals that drank of the water impregnated with it. It is also fatal to 

 vegetable life, and any pond treated with this material in liberal quan- 

 tities would be completely cleared of all animal and vegetable life, and 



