BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 17 
European Chafer Attracted to Chemically Baited Traps 
In tests to find an effective chemical attractant for the European 
chafer, a 3 : 1 mixture of Java citronella oil and eugenol gave the best 
results. Traps painted Chinese red were slightly more effective than 
black or other colored traps. Traps baited with Java citronella oil 
caught more beetles than did traps using live, laboratory-reared virgin 
female chafer beetles, field-collected female beetles, or extracts from 
female beetle abdominal tips. The Cornell June beetle trap, larger 
than the standard Japanese beetle trap, caught more beetles than any 
of the Japanese beetle traps. Painting the baffles of traps with auto- 
motive grease (ordinary high-pressure chassis lubricant) increased 
the catch in all types of traps over ungreased traps. Standard Jap- 
anese beetle traps painted black and with the baffles greased, set up 
singly at points along the periphery of the infested area, caught a 
few beetles in areas where the infestation was known to be extremely 
light. 
Chemical Treatment of Nursery Stock Destroys European Chafer 
During the fall of 1951 a schedule was developed for the treatment 
of large nursery trees with an ethylene dibromide-chlordane mixture 
applied as a fumigant. The principal requirement of this schedule 
is an application of 40 milliliters of the ethylene dibromide-chlordane 
concentrate in 1 gallon of water to each square yard of soil surface 
around the tree. This is done 5 days before the tree is dug and at a 
temperature of 50° F. or above. Trees treated in this manner in the 
fall are safe for movement to points outside the European-chafer- 
infested area. Similar treatments applied in the spring did not kill 
all the grubs, which by that time were nearly full grown. 
Quicker Vapor-Heat Process for Citrus Fruit Sterilization Developed 
Improvements have been sought in the vapor-heat method of ster- 
ilizing citrus fruits to destroy any fruit fly infestation before their 
certification to uninfested areas. The work lias been done in the Mexico 
City laboratory in cooperation with the Mexican Secretaria de Agri- 
cultura y Ganaderia. This method involves heating the citrus to a 
designated temperature by saturated vapor for a specific period. It 
has been used in Texas for the sterilization of one-half million tons 
of citrus for markets that otherwise would have been closed to the 
fruit. The objective of the present work is to develop a much quicker 
process by use of higher temperatures. Records obtained on an esti- 
mated 2,800,000 larvae in more than 40 tons of infested fruit indicate 
that sterilization of fruit with a quick runup of the temperature to 
115° F. in a period of not less than 4 hours will give adequate security 
against fruit fly survival. 
More Tree-Owner Participation in Hall Scale Control Ohtained 
Removal of host seedlings from waste areas, initiation of a more 
active voluntary host-removal program, tree fumigation, and applica- 
tion of two oil sprays to suppress Hall scale infestation continued in 
1951 as measures to eradicate this introduced and potentially serious 
pest of peaches, almonds and related hosts. The scale is known to 
