16 ANNUAL REPORTS 01 DEPARTMEN1 OF AGRICULTURE, 1051 
Benzene Hexachloride \\ idelj Accepted b) Lumber Industry for 
Control of imbroeia Beetles 
The lumber industry is using more and more widely benzene hexa- 
chloride sprays developed in Mississippi and bested in the Gulf States 
for the | not r.-t mn of logs and lumber from attack by ambrosia beet les. 
The increased use of these sprays coincides with ;i greater need for 
their protective qualities. Timber values are increasing and stock 
piling of logs is being more generally practiced. This leads to in- 
creased danger from uncontrolled ambrosia beetle activity. Use <»f 
the sprays has also been extended to the Tropics, where the beet les 
particularly troublesome. Requests for information on the subject 
nave been received from many parts of the world. 
Ethylene Dibromide Simplifies Fighl igainsl Hark Heetles 
Development of a water emulsion of ethylene dibromide has elimi- 
nated the necessity for transporting into the forest large quantities 
of fuel oil to be used in sprays to control Black Hills beetles infesting 
pines in the Rocky Mountain area. Ethylene dibromide in oil solu- 
tion is effective against the Engelmann spruce beet le and several other 
bark beet les, 
Weevil-Resistant Pine Hybrids Developed 
Several pine hybrids developed by the Forest Service's [nstitute of 
Forest Genetics at Placerville, Calif., have been tested for resistance 
to tli«' pine reproduction weevil. The most outstanding resistant 
hybrid yet produced is a backcross obtained by pollinating Jeffrey 
pine cones with the pollen of a natural hybrid of Coulter and Jefl rey 
3. This hybrid retain- the desirable silvicultural characters 
and wood qualities of its Jeffrey parent, a species highly susceptible 
to the weevil, and the resistant qualities of its Coulter parent, a species 
not injured by i he weevil. 
Cooperative studies with the [nstitute <d" Forest Genetics showed 
that the immunity of Coulter pine to weevil injury may be attrib 
to failure of the weevil to tolerate the turpentines of this sp< 
The same turpentines are present in the Jeffrey-Coulter hybrid, 
i hereby rendering it resistant. 
Turpentine Beetles Become \ icious Tree Killers 
A.fter long being considered of secondary importance, the black 
turpentine beetle in the South and the red turpentine beetle in the 
Cleveland National Forest in California have developed almost simuK 
taneousl} into primary tree killers. Until 2 or 3 years ago the black 
Lurpentine beetle was known to breed largely in pine stumps in the 
Deep South. Although it attacked standing net'-, it rarefy caused 
their death. Recently, reports have been received from many parts 
of the infested area telling of tree killing by this species in -lands 
following cutting operations and in turpentine orchards. Shade 
una isolated countryside tree- have also been destroyed. In 
California the red turpentine beetle was found attacking the under- 
ground portions of the main trunk and larger root- of livii g Jeffrey 
