ae 
15 
ever, describing the methods of using some of these substances which 
are easily available and will often be of service, particularly where 
few plants are to be treated. The standard remedies for this group 
of insects, viz, crude petroleum, kerosene, and kerosene emulsions, 
resin washes, lime-sulphur wash, hydrocyanic acid gas, and vapor of 
bisulphid of carbon, will be treated farther on. 
SOAPS AS INSECTICIDES. 
Any good soap is effective in destroying soft-bodied insects, such as 
aphides and young or soft-bodied larve. As winter washes in very 
strong solution, they furnish one of the safest and most effective means 
against scale insects. The soaps made of fish oil and sold under the 
name of whale-oil soaps are often especially valuable, but they are 
variable in composition and merits. A soap made with caustic potash 
rather than with caustic soda which is commonly used, and not con- 
taining more than 30 per cent of water, should be demanded, the pot- 
ash soap yielding a liquid in dilution more readily sprayed and more 
effective against insects. The soda soap washes are apt to be gelatin- 
ous when cold, and difficult or impossible to spray except when kept 
at a very high temperature. 
For aphides and delicate larve, such as the pear slug, a strength 
obtained by dissolving half a pound of soap in a gallon of water is 
sufficient. For the pea aphis as little as 1 pound of potash fish-oil 
soap to 6 gallons has been effective. Soft soap will answer as well 
as hard, but at least double quantity should be taken. 
Asa winter wash for the San Jose and allied scale insects, whale-oil 
or fish-oil soap is dissolved in water by boiling at the rate of 2 pounds 
of soap to the gallon of water. If applied hot and on a comparatively 
warm day in winter, it can be easily put on trees with an ordinary 
spray pump. On a very cold day, or with a cold solution, the mix- 
ture will clog the pump and difficulty will be experienced in getting it 
on the trees. Trees should be thoroughly coated with this soap wash. 
Pear and apple trees may be sprayed at any time during the winter. 
Peach and plum trees are best sprayed in the spring, shortly before 
the buds swell. If sprayed in midwinter or earlier, the soap solution 
seems to prevent the development of the fruit buds, and a loss of fruit 
for one year is apt to be experienced, the trees leafing out and grow- 
ing, however, perhaps more vigorously on this account. The soap 
treatment is perfectly safe for all kinds of trees, and is very effective 
against the scale. With large trees, or badly infested trees, as a pre- 
liminary to treatment, it is desirable with this as well as other appli- 
cations to prune them back very rigorously. This results in an econ- 
omy of spray and makes much more thorough and effective work 
possible. The soap can be secured in large quantities at from 34 
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