ENTOMOLOGY AND PLANT QUAKAXTIN1-: 
79 
REFRIGERATOR CARS AS FUMIGATION CHAMBERS 
The ordinary refrigerator car has been shown to be a very effective fumiga- 
tion chamber, and fumigations of vetch seed against the vetch bruchid, applied 
in the car under commercial conditions, have given a complete kill. As a 
matter of fact, the cars were found to be more satisfactory than many fumi- 
gation chambers, though good results are obtained in tight vaults. 
METHYL BROMIDE AS A FUMIGANT 
In cooperation with other divisions of this Bureau, methyl bromide, which 
has only recently been suggested as a fumigant, has been tested against various 
insects and with various types of plant products, especially fresh fruits and 
vegetables and greenhouse plants. It has been used with lima beans, egg- 
plants, cucumbers, green string beans, sweetpotatoes, cantaloups, peppers, 
tomatoes, and potatoes, in concentrations suflBcient to kill the Japanese beetle 
in the packages, without injury to the product. 
Methyl bromide has been tested on loads of 25 bushels or more of green 
string beans packed in hampers and was found to be effective in killing the 
Japanese beetle at the center of the package at concentrations of I14 to 2 
pounds of methyl bromide per 1,000 cubic feet of space without injury to the 
beans. In experimental treatments a dosage of 3 pounds has frequently been 
used without injury. 
Eight different varieties of strawberry plants witli soil on roots, packed in 
crates ready for shipment to market and infested with larvae of the Japanese 
beetle, were fumigated with methyl bromide. In all cases complete mortality 
of the larvae was obtained, hnd the plants grown in the field with appropriate 
checks showed no evidence of injury. This treatment will materially reduce 
the cost of disinfesting millions of strawberry plants, which was formerly 
done by inspecting plants one by one and removing the beetles by hand. 
In preliminary experiments with methyl bromide in the fumigation of peach 
trees for controlling the oriental fruit moth there w^as complete mortality of 
Ihe insect with no apparent injury to the nursery stock. Thirty-one green- 
house plants were fumigated with a dosage of 3 pounds of methyl bromide per 
l.(»00 cubic feet without injury, with practically a complete kill of three vari- 
eties of aphids, the common red spider, one species of thrips, two species of 
mealybugs, and immature stages of the southern armyworm. Methyl bromide 
gives promise of being a good greenhouse fumigant at a temperature of 65° F. 
Special apparatus has been devised for introducing methyl bromide and other 
fumigants into refrigerator cars for the fumigation of carloads of produce 
without loss of the gas and with a good mixing of the gas in the car. 
LOW-TEMPERATURE TREATMENT OF GRAPES FOR MEDITERRANEAN FRUITFLY 
During the year it was shown that the low-temperature treatment for the 
Mediterranean fruitfly could be applied by cooling the fruit in a prc-cooling 
plant on shore and holding it at a temperature of 34° F. or slightly below 
that temperature for the required 12 days in the hold of a ship in transit. 
In this work the fruit (grapes) was cooled at Capetown, South Africa, and 
loaded on a ship, and the remainder of the treatment was applied en route 
to Southampton, England. Temperature-measuring instruments in the hold 
of the ship made possible an accurate determination of the temperature of the 
fruit by an observer who accompanied the shipment. By this method the im- 
portation of grapes from countries in which the Mediterranean fruitfly is 
found can be safely made to the United States, provided the conditions are 
such that treatment is properly applied. 
INSECTICIDE INVESTIGATIONS 
The only change in set-up of the investigations on insecticides since the last 
annual report was the closing of the laboratory at Wooster, Ohio. The study 
of the characteristics and effectiveness of oil emulsions which was under way 
there was discontinued, and the chemist concerned was transferred to Belts- 
ville, Md., where he is developing stickers for use with phenotliiazine, nicotine- 
peat, and other organic insecticides which have been found insufficiently ad- 
hesive of themselves. 
