PETROLEUM PRODUCTS FOR MOSQUITO CONTROL 
335 
chased and transportation expense. In the 
field it spreads well, produces practically 
100 per cent kill of larvae and pupae within 
one hour, leaves a stable film, and is not 
disagreeable to the oiling crew. These 
specifications are not rigid and can be 
readily modified to meet different require¬ 
ments. The low boiling fraction may be 
decreased in areas where high temperatures 
prevail and where spreading and penetra¬ 
tion are comparatively rapid, and increased 
where waters are cool or during seasons of 
low temperatures. 
TABLE II 
Type, distillate fuel; gravity (A.P.I.), 27-33; 
flash 130° F or higher; viscosity S.U. at 100° F, 
35-40; odor, none offensive; distillation, 10% at 
430°-450° F and 50% at 510°-550° F (the killing 
fraction), and 90% at 630° F and higher (the 
lasting fraction). 
4. Spreading and Penetration. Ordi¬ 
narily a non-viseous, toxic mosquito oil as 
above described spreads well on clear water 
surfaces, producing uniform film. On 
waters covered with flotage, debris, scum, 
thick vegetation and similar impeding ob¬ 
jects, spreading speed is considerably 
slower, often resulting in unprotected areas 
where larvae may continue to develop un¬ 
disturbed. This is especially apt to occur 
in early spring or fall, when the water tem¬ 
perature is comparatively low. In such 
instances application under high pressure 
may force the film through the* covered 
areas (Griffitts 1925; Coggeshall 1930; Wat¬ 
son and Bishop 1940). When power spray¬ 
ers are not available the use of spreading 
agents in the oil may be advisable. The 
work of Langmuir (1917), Harkins (1917) 
and the more recent studies of Ginsburg 
(1927) and Murray (1939) have shown 
that oil-soluble organic compounds possess¬ 
ing either unsaturated bonds or polar 
groups in their molecule, such as -OH, 
-COOH, with marked affinity for water 
may greatly improve the spreading of 
petroleum oil. In practice, small quanti¬ 
ties (0.5-2%) of the following compounds 
were found helpful: cresylic acid, xylenol, 
oleic acid, turpentine, monohydric alcohols 
and sulphonated derivatives of petroleum. 
5. Quantity of Oil per Acre. The amount 
of oil necessary to produce a uniform kill¬ 
ing film in the field may vary from 25 to 
60 gallons per acre, depending on the 
nature of the breeding area, toxic proper¬ 
ties of the oil, species of mosquitoes, method 
of application and atmospheric factors such 
as prevailing wind and temperature. Usu¬ 
ally more oil is required per acre of water 
surface covered with debris or vegetation 
than on clear water. It will also take more 
oil to cover a given area at low tempera¬ 
tures, such as prevail in early spring, than 
during the summer months. Where power 
sprayers capable of developing 100 pounds 
or more pressure are available, a killing film 
can be laid down with less oil than where 
hand sprayers are used. Anopheline lar¬ 
vae, because they stay near the surface most 
of the time, are effected by thinner films of 
oil and die during shorter periods of expo¬ 
sure (LePrince et al. 1916; Green 1924), 
than culex larvae or other bottom feeding 
species. 
Oil-Pyrethrum Larvicide 
Mosquito control workers frequently en¬ 
counter objections against the application 
of oil. There is a large number of private 
and municipal ponds, streams, and areas of 
impounded waters where fish and water 
fowl prevail and where aquatic plants are 
grown. Many of these places are favorable 
for mosquito breeding. Owners and au¬ 
thorities in charge of these places object, 
however, to the use of oil. Objections are 
raised also by preserve owners, game breed¬ 
ers, and those interested in propagation and 
conservation of wild life, waterfowl and 
game fish. In order to furnish mosquito 
control workers with an efficient substitute 
for oil, the New Jersey Pyrethrum Mos¬ 
quito Larvicide was developed (Ginsburg 
1930; 1934; 1939). Since its introduction 
it has been widely used in New Jersey and 
in other States (Yannote 1931; Smith 
1932; Clarke 1936; and Rice 1936). It is 
primarily an oil emulsion of approximately 
the following composition: 66 per cent kero¬ 
sene or similar light petroleum distillate; 
0.07 per cent pyrethrins; 33.5 per cent 
