CHAPTER XVIII 
SOME INSECT PESTS OF GARDEN AND FIELD 
There are said to be about six hundred different species 
of insects that are more or less injurious to vegetation, and 
it is fortunate that they are not all found in one section. 
Those that are most common in any locality are the ones 
that should be selected for most careful observation. To 
assist in this work we briefly describe a few of the most im- 
portant kinds that the student is apt to meet. 
As these studies are to help us cope with insect pests more 
intelligently, and as frequent reference is made to poisons 
and sprays, let us first explain the principle that determines 
our procedure with these remedies. 
Insect Poisons and Sprays. — When our potato patches, 
fruit trees, vegetables, or flowers are infested with insects, 
we usually spray them. To do this intelligently we must 
know whether the species is one that chews its food or sucks 
the sap of plants. Potato beetles and cabbage worms, for 
example, eat the leaves, and we may kill them by putting 
poison on their food. It is generally applied in a liquid 
form by spraying or sprinkling. Paris green has long been 
the standard remedy for this purpose, but arsenate of lead 
is also used extensively and is to be preferred for some pur- 
poses. For currant worms hellebore is commonly employed. 
_ Plant lice are an example of sucking insects, and these are 
killed by spraying them with a contact remedy — one that 
kills when it gets on their bodies. Some of the remedies 
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