INSECT ENEMIES OF EASTERN FORESTS 39 
and enter the wood before damage occurs. Recently some effective 
sprays have been developed which will prevent the attack of ambrosia 
beetles and borers for at least 2 to 4 months. Where it does become 
necessary to use such methods, a fuel-oil solution of benzene hexa- 
chloride containing a 0.4 percent concentration of gamma isomer by 
weight is by far the most efficient material known. but the logs must 
be very thoroughly covered with it. Barking the logs will prevent 
borer but not ambrosia beetle attack, but this is frequently impractical 
because of the rapid drying and checking which results. © It can, how- 
ever, be used to advantage - where spec ial circumstances permit, as for 
protecting pulpwood. 
Benzene hexachloride is poisonous and should be handled with 
care. It should be stored in clearly labeled packages and kept 
away from food products. 
Floating the freshly cut logs in fresh-water millponds or streams 
until they can be put through the sawmill is effective in materially 
lessening the attacks of nearly all wood borers and ambrosia beetles. 
In the Southern States high-floating logs wili be attacked on the top 
sides by ambrosia beetles and by some borers. It is best, therefore, to 
hold the logs or rafts in open water where they will receive the full 
effects of the sun. They will be further protected if sprayed with 
benzene hexachloride in fuel oil. Many logs can be stored for indefi- 
nite periods in water without any deterioration, but some hardwoods, 
such as hickory, will be darkened if submerged. 
In addition to the defects made by the insects tunneling through 
the bark and wood of green logs, there often results a further. deprecia- 
tion due to blue stain, “which is carried into the wood by bark and am- 
brosia beetles as they make their tunnels. The sapwood of green logs 
and lumber may be blued within 2 to 3 weeks from the time ot felling, 
unless care is taken to prevent it. 
PROTECTING GREEN LUMBER 
Green lumber is frequently attacked by ambrosia beetles and wood 
pores particularly if the bark is not removed from the edges or if a 
rainy period occurs after the sawing, which retards the dryi ing of the 
stock. To prevent pinhole defects ‘caused by ambrosia beetle attack, 
ereen lumber should be piled so that it will season as rapidly as possi- 
ble without checking. Valuable hardwood lumber should be end- 
racked for 10 days or 2 weeks, or until the moisture content is reduced 
to 50 percent or less. It should then be transrerred to storage piles 
well provided with stickers. Spacing between piles should be adequate 
to allow for free circulation of air. Another effective means of pre- 
venting or checking ambrosia beetle attack is to kiln-dry the lumber. 
Christian (SI) indicated that a few chemical sprays have proved effec- 
tive in preventing ambrosia beetle attack in piled lumber, and that sap 
stain was prevented in experimental work. More recent tests have 
proved that an aqueous suspension containing 0.2-percent gamma 
isomer of benzene hexachloride is the most pean e spray. 
The attack of wood borers is readily prevented by the removal of 
the wane from the edges of the boards, and this should be done before 
the spring and summer months—that is, before the flight period of the 
adult beetles. 
