98 ANNUAL REPORTS OP DEPARTMENT OF AGRICULTURE, 1939 
the California red scale in quarantine work, because of the high con- 
centrations necessary to give a complete kill. Even at the rate of 
7.5 pounds per 1,000 cubic feet there were occasional survivors in 
some Stages. This work also gave an opportunity for studying the 
effect of methyl bromide on late pupae and unemerged adult- of a par- 
asite (GomperieUa bifasciata Howard) of the yellow scale, and pupae 
of a predator {Gouwentzia /tar/mi Banks) of the citrus red mite. 
CHEMICAL INVESTIGATIONS ON ACCESSORY MATERIALS FOR USE WITH 
INSECTICIDES 
Studies were made of the effect, upon the wetting and spreading 
power of a commercial wetter, of the addition of calcium and ma<j- 
nesium salts, simulating its use in hard water. A relationship was 
demonstrated between the wetting power of spray solutions, as deter- 
mined by the standard method used in the Division, ami the initial 
retention of the solution by a -prayed fruit surface. 
The intensive search for stickers for nicotine-peal and phenothiazine 
was brought practically to a close, without any very striking results. 
Of the nine stickers used with nicotine-peat, bentonite proved to he the 
only all-around satisfactory one when items of cost, availability, con- 
venience, etc., were considered along with its actual performance. In 
the work with phenothiazine attention was paid not only to plain 
stickers, but also to antioxidants, in the belief that some of the lack 
of persistence is to be charged to decomposition rather than to mechan- 
ical loss. Many of the accessory materials hasten the decomposition, 
and the phytocidal action of any heavy deposits produced and main- 
tained may offset considerably any insecticidal improvement. Short 
cellulose fibers from hemlock were given a trial, hut were not par- 
ticularly effective. 
Much work was devoted to accessories for use with the tank-mix 
nicotine bentonite which is proving so successful against the codling 
moth. Its compatibility, as judged by maintenance of insoluble nico- 
tine, with soaps, wetting agents, oils, copper fungicides, and lime- 
sulfur was studied, and it was found that any material with a marked 
alkaline reaction liberated the nicotine and hence may he judged 
incompatible. Variations in formula did not lead to any improvement 
over the already adopted formula for the nicotine bentonite. 
A study was made of adjuncts for use with the standard Japanese 
beetle bait as a possible means of improving the attractiveness of the 
geraniol to last throughout the season. The value of antioxidants 
was explored, and it appears I hat basic substances are definitely barred, 
but that acids such as citric, acetic, and phthalic may have some value. 
The possibility of substituting thymol, safrol, phenol, and other similar 
materials for the eugenol commonly employed is also being studied. 
The question of the suitability of diluents for use with powdered 
insecticides was brought to the fon> by the investigation which was 
Started in conjunction with Mormon cricket control. Numerous com- 
mercially available diluents were tested as to particle size and a- to 
their tendency to separate from mixtures with sodium arsenite and 
white arsenic when blown from a dust Linn, and indications obtained 
that there are probably more suitable ones than the diatomaceous earth 
now used. 
