66 
F. & F. NURSERIES 
Some Facts About Controlling Insects on 
Ornamental Plants 
Because of the many different kinds of ornamental plants and the 
thousands of insects attacking these plants, it is impossible to give con¬ 
trol methods here for all these insects. Therefore, this brief article is 
presented on some of the fundamental principles of insect control. 
Difficult cases of insect control should be referred to us or to your State 
Entomologist for advice. 
IMPORTANCE OF FEEDING HABITS 
The method of controlling any specific insect is largely determined 
by the manner it obtains its food. If it bites off, chews and swallows 
solid particles of the foliage, bloom or fruit it can often best be controlled 
by stomach poisons, such as arsenate of lead, fluorine compounds, etc.; 
if it obtains its food by inserting its mouth parts through the surface 
and sucking out the plant juice, one must use contact poisons, such 
as nicotine, rotenone, pyrethrum, etc. The above two methods are 
effective where the insects feed upon exposed surfaces. If they bore 
inside the leaves, fruit, stems, trunk or roots, other methods are often 
necessary. Thus, how the insects feed and their habits have an important 
place in how to control them. 
STOMACH POISONS 
The most common stomach poison for use on ornamental plants is 
arsenate of lead. It may be obtained in a white powdery material, or 
in a paste form. The powder is usually used at the rate of 1 H pounds 
to 50 gallons of water or in smaller quantities 1 ounce to 2 gallons or 
1 rounding teaspoonful to 1 quart of water. Spray thoroughly all parts 
of the plant likely to be fed upon. 
Powdered derris root or powdered pyrethrum flowers or dusts con¬ 
taining these insecticides also have some value as stomach poisons for 
ornamental plants where one does not wish to use an arsenical poison. 
These powders may be dusted upon the plants or applied as a spray 
by diluting at the rate of 1 pound to 3 to 5 gallons of water. They act 
as contact poisons and repellents as well as stomach poisons, but will 
not protect the plants for as long a time as lead arsenate against leaf 
eating insects. 
Stomach poisons may be used against insects such as most beetles, 
grasshoppers, caterpillars, etc. They are not effective against plant 
lice, scale insects, leaf hoppers, various plant bugs, etc. 
CONTACT SPRAYS 
Contact sprays are of two kinds. Those used on plants during the 
growing season and known as summer contact sprays, and those used 
on hardy plants while they are in a resting or dormant stage, are known 
as dormant sprays. 
Summer contact sprays are of many kinds. The most common ones 
contain either nicotine, extracts of pyrethrum flowers (pyrethrins) or 
extracts of derris or cube roots (principally rotenone) as the principal 
killing agent in water, alcohols or oils. Soaps and the so-called white 
oils are also effective against some insects, such as plant lice, crawling 
stages of scale insects or other young insects. There are so many differ¬ 
ent kinds of contact sprays and they vary so much in their composition 
and formulae that general directions are difficult to give. State and Fed¬ 
eral laws require that they be true to label and directions; therefore, 
they should be used as directed on the containers. 
Contact sprays kill by wetting the surface of the insect to be killed. 
Therefore the spraying should be thoroughly applied to all parts of the 
plant, both upper and lower leaf surfaces. Many contact sprays con¬ 
tain either soap, oils or other materials to make the diluted spray wet 
better. If they do not contain a wetting agent or if the dilution with 
water is rather high, they can often be made more effective by adding 
soap. Powdered or dry soaps should be used 1 part to about 200 parts 
of the diluted spray. Liquid soap should be used diluted from 2 to 4 
times as much as the actual amount of soap they contain. Thus, a liquid 
soap containing 15 % actual soap should be added 1 part to 30 to 60 
parts of the diluted insecticide spray or liquid soap containing 40% 
actual soap should be added 1 part to 80 to 160 parts of the diluted 
insecticide. The concentration of soap will depend upon how hard^the 
insects are to kill and whether the plants are tender or hardy. 
The insects controlled with summer contact sprays may be divided 
into several groups according to their habits and difficulty of control. 
These groups are as follows: 
PLANT LICE (also called aphids and green fly), infest many differ¬ 
ent kinds of plants. Soft bodied, whitish, green, brown or sometimes 
almost black in color, usually not more than }/% inch long. Generally 
found clustered on the under surface of leaves, or along the new growth 
of stems. To control, dip or spray plants in any of the summer contact 
