INSECT ENEMIES OF EASTERN FORESTS 53 
ing certain insects, such as rose chafers, loopers, and small canker- 
worm larvae than is nicotine sulfate. Wetting and spreading agents 
increase the efficiency of low concentrations of pyrethrum. Recent ex- 
periments indicate that derris is more effective than nicotine or py re- 
thrum against spider mites. DDT, benzene hexachloride, and chlor- 
dane are among the newer insecticides that are very effective in con- 
trolling leaf-eating insects. Although DDT is no cure-all and does 
not kill certain aphids and mites, it is the most effective contact in- 
secticide known at present. Oil emulsions and miscible oils are used 
principally in dormant spraying, and for the control of scale insects, 
spider mite and aphid eggs, and other stages of insects that pass the 
winter on dormant trees. Thin, miscible, “white oils of about 50 sec- 
onds (Saybolt) viscosity are better than nicotine or derris for con- 
trolling the summer stages of scale insects, certain woolly aphids, 
mealybugs, and spider mites. Lime-sulfur is used as a dormant spray 
for the control of certain scale insects, casebearers, and other pests. It 
may also be used as a Summer spray. 
FORMULAS 
Although no attempt will be made to list all the different insecticides 
that have been developed, a few of the most important will be given 
with formulas for the preparation of concentrations commonly em- 
ployed in controlling forest and shade-tree pests. Recent develop- 
ment and improvement of spraying apparatus, which include mist 
blowers, airplanes, and helicopters, make it practical to apply insecti- 
cides and fungicides in the form of concentrated sprays at a low dosage 
and gallonage per acre. Some of these formulas are not safe to use 
in the conventional types of power and knapsack sprayers because 
of the danger of burning foliage and, therefore, formulas for the 
conventional types of sprayers are given separately from those for dis- 
tribution from aircraft or by mist blowers. 
Amounts of insecticides required to prepare 100-gallon and 1-gallon 
quantities are given. It will be noted that the amounts of insecticides 
required to prepare 1-gallon lots are given in metric units, as well as in 
more practical units, such as teaspoonfuls. If lead arsenate and nico- 
tine sulfate are used in combination, soap should be omitted. 
The following formulas are for use in controlling forest and shade- 
tree pests: 
For large quantity For small quantities 
Insecticides: 
(1) Lead arsenate (powdered) -_____________-_- 4 1b. 18.2 gm. 9 teaspoonfuls. 
Wit Crieteiae ee a Se os a 100 gal. 1.0 gal. 1 gal. 
Mishgoilcorslinseed: oils <5. S22 e ees kh 1 pt. 4.7 ce. 1 teaspoonful. 
(2) Derris or cube powder (4 percent rote- 4 |b. 18.2 gm. 13 teaspoonfuls. 
none). 
Wit Creare earn eo es 100 gal. 1.0 gal. 1 gal. 
Kishzoiltonlinseedvoile— se 2 qt. 18.9 ce. 4 teaspoonfuls. 
(3) DDT wettable powder (50 per- 0.5 to 1.5 1b. 2.27 to 6.8 gm. 1 to 3 teaspoonfuls. 
cent DDT). 
WiGlGG Tears sree Be 100 gal. 1.0 gal. 1 gal. 
(4) DDT emulsion. (Dilute according to 
manufacturer’s directions.) 
(5) Nicotine sulfate (40 percent nicotine)____ 1 pt. 4.7 ce. 1 teaspoonful. 
Witte eae re rene ee ea oe 100 gal. 1.0 gal. _ gal. 
SOmMESOliG) esate 2 eee mee 3 libs 14.0 gm. Piece size of yeast cake. 
or 
leiqquiGksoap sen ae ee S=6xpt= 28.0 ce. 6 teaspoonfuls. 
(6) Pyrethrum powder or extract (1 per- 1.66 Ib. 7.6 gm. 5 teaspoonfuls. 
cent total pyrethrins). 
Wa eloenera ret eth fa 100 gal 1.0 gal. 1 gal. 
SOAR GOlG) meas ne Oe ee 3 1b 14.0 gm. Piece size of yeast cake. 
or 
TARO TOOLS Gps oy 2 ees ee ee 6 pt. 28.0 ce. 6 teaspoonfuls. 
