TERMITES IN THE UNITED STATES. 31 
a treatment to render timber more resistant to attack by insects. 
Wood soaked in a 2 per cent solution is under test. 
STOEED MATEKIAL. 
Injury to books, paper, documents, and other stored material or 
products is usually indirect, the insects as a rule burrowing through 
such material only where it is in contact with infested wood. Hence, 
since the source of infestation is decaying wood, if the insects can 
be kept out of wooden structures this damage can be prevented. 
When once the source (white ants coming up through the earth where 
there is moisture) is shut off, the insects infesting stored material 
soon die out or can be killed by spreading out infested books, docu- 
ments, and other stored material or products to dry in the sun or in 
an oven. Later they can be restored to the repaired building or a 
safer place. Most damage of this sort can be prevented by the sub- 
stitution of concrete foundations to buildings or by using timber 
impregnated with coal-tar creosote. 
FUMIGATION. 
Where the injury is confined to books and papers, other stored 
material, or exposed woodwork and furniture, hydrocyanic-acid gas 
fumigation can be attempted, exposing if possible also, by opening 
up floors, the infested joists beneath and spreading out the books 
and opening cases and wardrobes. As Irydrocyanic-acid gas is poison- 
ous and dangerous, fumigation should be attempted only by those 
with experience. 1 
LIVING TKEES. 
Owing to the subterranean habit of termites, it is extremely diffi- 
cult to prevent or remedy injury to living forest, fruit, or shade 
trees. Care should be taken that the trees do not become scarred near 
the base, in order to prevent heart rot and subsequent infestation. 
Proper clean forest, orchard, and horticultural management is to be 
recommended. Properly executed tree surgery 2 sometimes may be 
effective in repairing damage to valuable old trees. Dead and dying 
infested trees should be removed and burned. Prunings should not 
be loft lying on the ground, but should be burned. 
NURSERY STOCK, FIELD CROPS, AND VINEYARDS. 
Injury to nursery stock will be most serious on recently cleared 
land where there is abundant decaying wood. Such debris, in which 
the insects breed, should be removed. In general, the use of recently 
1 For a description of the use of hydrocyanic-acid gas see Howard, L. O., and Popenoe, 
C. H., Hydrocyanic-acid Gas Against Household Insects, U. S. Dept. Agr., Farmers' 
Bui. 699. 
2 Collins, J. F. Practical Tree Surgery. In U. S. Dept. Agr. Yearbook for 1913, p. 
163-190, pi. 16-22, 1913. 
