BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 7 
Blastophaga, the fig-pollinating insect. Although no completely effective method 
of freeing the figs or the Blastophaga wasp from spoilage micro-organisms ran 
yet be recommended, definite progress has been made. 
SUBTROPICAL FRUIT INSECTS 
In two experiments in Florida in the control of the citrus rust mite on orange 
trees, the addition, to the standard lime-sulphur solution, of aluminum sulphate 
with hydrated lime as an adhesive was found to prolong the spray protection 
considerably, so that fewer sprayings were necessary during the year. Wet- 
table sulphur as a spray, without adhesives, was distinctly interior to lime- 
sulphur, but with these adhesives it was a promising control mixture. Control 
of the rust mites was obtained also with two applications of sulphur dust from 
a ground dusting machine. This method of control compared favorably with 
spraying, although in one case heavy rains necessitated redusting in a week's 
time. Even in this plot three dustings sufficed for the season. 
Extensive field experiments have been carried on in the control of the orange 
thrips. In the Redlands-Rialto section of California three applications of 
sulphur dust have continued to give control better than that obtained by a 
single application of liquid lime-sulphur. Sulphur dusts containing compounds 
of zinc (used for the control of the condition known as mottle-leaf), in propor- 
tions ranging from 4.5 to 11 percent, on a basis of metallic zinc, seemed as 
effective in thrips control as sulphur dust alone. Little control of the thrips 
was obtained by the use of dusts of derris. pyrethrum. or rotenone with inert 
carriers. Experiments in dusting with sulphur for thrips control were also 
carried on in the Salt River Valley of Arizona. 
AYork with the California red scale has been continued in southern California. 
in cooperation with the Division of Insecticide Investigations. A long series of 
field fumigations has been carried on in accordance with commercial practice 
and record made of all conditions that might influence their effectiveness. Gas 
samples were taken at intervals from under four tents at each treatment to 
determine the concentrations through the period of treatment, and detailed 
records were made of the proportions of the scale insects in various stages, of 
the mortality resulting from the treatment, and of the effect of the treatment 
on the trees and fruit and also on the subsequent yield. 
The experiments carried on in cooperation with the Bureaus of Plant Industry 
and Chemistry and Soils to determine the effect of tartar emetic when used 
as an insecticide spray on citrus trees have been continued. In general, the 
results obtained thus far seem to indicate that tartar emetic applied as a mist 
spray at strengths up to and including 8 pounds per 100 gallons of spray mix- 
ture has little or no effect on citrus foliage or fruit. 
THE RHINOCEROS BEETLK IX PUERTO RICO 
The rhinoceros beetle Striiteffus quadrifoveatus Beauv. is the most serious 
pest of coconuts in Puerto Rico. It attacks and finally kills approximately 73 
percent of the young replanted palms during the first 3 years of their life. In 
studies carried on with special funds emphasis was placed on the development 
of control measures. Two of the most promising and economical methods of 
control are (1) wrapping the nut and the lower 5 inches of the sprout of the 
seedling palm with %-inch square mesh, galvanized-iron wire hardware cloth 
before planting, and (2) grove sanitation in which all decayed wood, particu- 
larly that of coconut and other palms, is destroyed. The former method lias 1 
given immediate and absolute protection that will probably last beyond the 
most vulnerable period in the life of the palm at a cost of about 25 tents per 
palm. From the data thus far obtained on the latter method it appears that 
grove sanitation will be commercially effective beginning approximately (5 
months after its initiation, provided it is carried out carefully and on a 
community or sectional basis. 
COFFEE INSECTS IX PUERTO RICO 
The Investigations on coffee insects in Puerto Rico were directed principally 
to the relationship between ants and scale insects and mealybugs. Two species 
of ants were frequently found associated with Infestations of scale insects on 
coffee, but neither of these appears materially to affect the scale population 
through protecting the scale- from parasites or predators. 
A survey has been made of the parasites of the coffee leaf miner I L< ur<>i>t> ra 
coffeella Guer. ). 
