62 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE, 1953 
There was increased acceptance of the voluntary host-removal pro- 
gram in the treated areas. More than 4,300 hosts were voluntarily re- 
moved and destroyed during the year, 2,254 of which were in the Oro- 
ville area. This represents removal of approximately 71 percent of 
the hosts there. In addition, more than 5,100 volunteer seedlings were 
removed from the vicinity of infested plantn 
Sprays Nonpoisonous to Natural Enemies of Apple Pests 
Investigated 
Investigations were expanded on the effects of insecticides on the 
Datura] enemies of apple pests in Eastern States orchards, in order 
more effectively to coordinate biological with chemical control. 
Other orchard tests in the State of Washington showed that a new 
spray, Q,-K)7, has more harmful effects on the coccinellid beetle 
Stetkorus picipes, a predator on phytophagous mites than does DDT. 
Among various insecticides tested for control of the codling moth 
CS-708 was found to have the most harmful residual effect on Sti tho- 
rns. Studies at another orchard showed that Sti thorm utilizes mites 
on various legumes to build up high population- and then becomes 
active on apple trees in numbers exceeding anything expected on the 
basis- of mite populations on the trees. It was also observed that 
Stethorus beetles become fairly abundant on unsprayed legumes in- 
fested with mites outside the orchard. When the mite population 
there becomes low, the beetles move to the cover crop legumes in the 
sprayed orchard and rapidly reduce the mite population on these 
legumes. 
HONEY BEES AND OTHER POLLINATING INSECTS 
Antibiotics Effective Against Destructive Honey Bee Diseases 
Fumagillin, an antibiotic, may be ell'ective against Nosema disease 
in honey bee-, according to experiments conducted in 1952. Bees inoc- 
ulated with the disease and fed with this substance at concentrations 
of 1G.7 mg. pei- liter of sugar sirup remained essentially free of infec- 
tion. Bees heavily infected I'd- 7 to 9 days showed a more or less 
constant decrease in the Level of infection following continuous feed- 
ing of fumagillin. This antibiotic appeared ineffective, however, 
when given in water. Tests are continuing to determine the optimum 
effective concentration of fumagillin, its effect on longevity, and sta* 
bility in various solvents and food substances. 
St reptomycin at 0.6 gram per gallon of SUgax sirup, gave promising 
results against European foulbrood when \\^\ to infected colonies at 
Madison, Wis. 
Steam Sterilization Kids Pollen of Foulbrood Contamination 
A method for Bterilizing pollen that may he contaminated with 
European foulbrood organisms was developed at the Bureau's Labo- 
ratory at Madison, Wia Steam autoclaving for 20 minutes at a pres- 
sure of l ! pound- produced the temperature necessary to sterilize the 
pollen if it is spread sufficiently to allow penetration of the steam. 
Pollen treated in this way seemed to be as palatable as untreated pollen 
