BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 91 
ing the latter part of 1938, -and 483 adult Chelorws sp., with 1,800 par- 
asitized host larvae, in the spring of 1939. 
A new activity of the European station is the collection and ship- 
ment of Meigeiiia floralw Meig., a parasite of the asparagus beetle 
which is effective in France, The first shipment, consisting of 497 
puparia and 4,800 parasitized larvae, was made in June. 
One consignment of 153 puparia of the European earwig parasite 
Rhacodineura antiqua Fall, was forwarded to the Puyallup, Wash., 
station to serve as a rearing stock for domestic production. 
A survey of the status of the pea moth was started in France during 
the year to determine if natural enemies play an important part in its 
control. 
EFFECT OF CHEMICAL CONTROL METHODS ON POPULATION OF NATURAL ENEMIES 
The major activities under this project have been concerned with 
the codling moth at Kearneysville, W. Va., the citrus scales and white- 
flies at Orlando, Fla., and the citrus scales and red mites in southern 
California. The codling moth experiment which is carried on in co- 
operation with the Division of Fruit Insect Investigations and the 
West Virginia Agricultural Experiment Station has shown for the 
third year that the production of clean fruit is approximately equal 
in sprayed and unsprayed orchards. The factors responsible for this 
condition have not yet been fully determined, but predacious ants ap- 
pear to be one of the most important. 
In the case of the fungus diseases of scale insects and whiteflies 
in Florida, it has been found that the fungi are of very little value in 
control and that fungicides can be applied for the control of citrus 
diseases without regard to the effect upon the forms parasitic upon 
insects. An improved sampling technique has been developed which 
appreciably reduces the time and labor involved in experimental work 
on this problem. 
The investigation on citrus insects and mites in California has 
shown, in the case of the black scale, that groves in certain sections 
may be left untreated without the development of a serious infesta- 
tion, while if fumigation or spraying is started in such groves the 
population of natural enemies is reduced and the treatments must con- 
sequently be continued. The heavy red mite infestation during recent 
years in southern California is correlated with the more general adop- 
tion of oil sprays against the scale insects, and where such treatment 
can be avoided the injury by red mites is much reduced. A mechani- 
cal device was developed for use in sampling experimental plots, and 
this permits of 200 trees being adequately sampled in 3 or 4 days. 
COOPERATIVE WORK WITH PUERTO RICO 
The cooperative work with the Puerto Rico Agricultural Experi- 
ment Station of the Office of Experiment Stations has been con- 
tinued, and the Division has provided directly, or through other Divi- 
sions of the Bureau, for the shipment to the island of five species of 
parasites of the lima bean pod borer from France, one pink bollworm 
parasite from Japan, and one parasite of the sugarcane borer from 
the United States. 
