BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 47 
than 100,000 acres of land had been cleared of this nuisance that crowds 
out desirable forage grasses. The remaining Klamath weeds in the 
southern part of this county are confined to widely separated, small 
roadside infestations of about 25 to 30 plants each. Distribution of 
the foliage-feeding beetles to new localities has been continued. Every 
county in the State having a Klamath weed problem now contains 
successful colonies of Chrysolina gemellata, originally introduced 
from Australia. Agrilus hyperici and Zeuxidiplosis giardi, intro- 
duced from Europe in 1950, have now completed 1 year in the field 
and are definitely established. The work in California was in co- 
operation with the California Agricultural Experiment Station at 
Albany. 
Chrysolina gemellata has also done very well in controlling the 
Klamath weed in southern Oregon. It kills the weed readily. The 
rate of increase indicates that the growth rate of the plant and the 
life cycle of the insect are well synchronized. Fourteen colonies of 
this species were introduced into the State of Washington for Klamath 
weed control there. In Idaho, this species has made excellent prog- 
ress. It was possible to collect enough beetles in Idaho to start 40 new 
colonies in weed-infested areas. The University of Idaho reported 
in November 1951 that an unusually large number of eggs was being 
found at that time. Approximately 280.000 adults of this species 
were released in 56 locations in western Montana. 
HONEY BEES AND OTHER POLLINATING INSECTS 
Wide Variation in Honey Production Among Bee Progeny 
Fifteen lines of honey bee progeny at the Madison, Wis., laboratory 
showed heritable differences in both production and behavior charac- 
teristics. The most productive lines produced an average yield of 239 
pounds of honey, or 2% times that of the least productive. 
Distribution was made of 1,262 hybrid queens reared on Kelleys 
Island, Ohio, in the bee-breeding project carried on there in coopera- 
tion with the Ohio Bee Improvement Association. 
Free-Flying Drones Best for Laboratory Breeding Purposes 
When sperm from free-flying drones was used in artificial insemi- 
nation experiments at Baton Rouge, La., 82 percent of the queens 
started laying. Out of a group of 68 queens inseminated with sperm 
from drones that never had a flight, only 44 percent lived to produce 
eggs. As a consequence emphasis is being shifted to the use of free- 
flying drones for a sperm supply. During 1951 nearly 900 insemina- 
tions were made of 570 queens. 
Bee Colonies Survive Prolonged Low Temperatures 
Two colonies of bees placed in a deep-freeze unit at the Madison 
laboratory on July 30 survived 6 to 7 weeks at temperatures of —40° 
to —50° F. These tests were preliminary to experiments on winter- 
ing bees in electrically heated hives under a cooperative project with 
the Division of Farm Electrification, Bureau of Plant Industry, Soils, 
and Agricultural Engineering. 
