INSECT ENEMIES OF EASTERN FORESTS 25 
General care of shade trees, such as avoidance of injury from lack 
of water, filling in of earth, or grading over the roots; care in trans- 
planting; and “thinning and pruning where possible, will help to 
prevent attack. In the early stages of attack by some species, while 
only the upper branches are infested and before the tree is completely 
girdled, it is helpful to improve the vigor of the tree by watering, fer- 
tilizing, and spr aying for sucking or defoliating insects, as explained 
elsewhere (pp. 20-23). Intr ansplanted stock, mechanical barriers are 
often effective. 
FUMIGATING TREATMENTS 
One of the most effective treatments for many borers is a spray 
carrying one of the common fumigants. Such sprays will not pene- 
trate green bark, but they are absorbed by any dead bark around the 
insect and enter the exudation holes maintained through the bark by 
certain species of borers, thus bringing the active ingr edient in contact 
with the larvae. 
Probably the best of these fumigant sprays is orthodichlorobenzene 
emulsion. ‘The stock emulsion is made as follows: 
Orthodichlorobenzene ere: ce 2h Dh eM R at, Pee eR eRe ROTEL SS 
Liquid potash soap, fish-oil soap, or common laundry soap ________ spate 
SOnt Wale ens etre eo ebeo Rie es see sss ee 3 parts. 
When laundry soap is used, the soap should be dissoly ed in boiling water and 
after it has cooled somewhat the orthodichlorobenzene should be added and the 
ingredients thoroughly mixed. 
If the water is hard, 1 teaspoonful of washing soda should be added to each 
gallon. 
Pumping the mixture through a coarse nozzle back into the same 
container will aid in insuring a good emulsion that will stand up for 
several months. To make the spray solution, 1 part of this stock 
emulsion is mixed with 6 parts of water. The emulsion should be 
thoroughly stirred both before diluting it with water and before ap- 
plying it to the trees, to be sure that the chemical has not separated 
out. The emulsion should not be applied to the foliage or tender 
branches, as it will cause burning. 
A simpler mixture consists of orthodichlorobenzene in a miscible oil. 
Naphthalene in a nontoxic carrier, such as an emulsion, has proved 
effective. 
Where only a few lightly infested trees are to be treated on the 
lower part of the trunk, it is often advantageous to paint the infested 
places on the bark with an emulsion rather than to spray. An ef- 
fective emulsion for this purpose is made up by dissolving 2 pounds 
of paradichlorobenzene in 1 gallon of crude cottonseed oil and emul- 
sifying the mixture with a good grade of potash soap or fish-oil soap. 
This stock solution should then be diluted with 2 to 4 parts of water 
and applied to the infested areas of the bark with a paint brush. The 
crystals can also be used in a mineral-oil emulsion. Chandler (S3 
in 1939 discussed the method. 
Paradichlorobenzene is a good fumigant for borers at the base of 
the tree. From 14 to 1 ounce of the crystals (depending on size and 
age of tree) should be placed on the loosened soil around and about 
