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Plant Enemies

Insects are divided into two great classes according to their method of feeding. Those which eat the foliage and plant tissues, and those which, instead of defoliating plants, insert their sucking beaks into the soft inner tissues for the purpose of extracting the plant juices. In this latter class may be included all kinds of plant lice, scale, thrips, white fly and mealy bug. The underlying principle in insect control is to determine to which of these two classes the pest belongs, because the insecticide used will depend upon the character of the enemy. This can be readily ascertained by observing the method of attack; if the leaves are riddled with holes it will be necessary to cover the plants with some stomach poison as arsenate of lead or paris green which will be swallowed with the plant, causing the insect's death. Sucking insects remain unharmed if stomach poisons are used as they thrust their beaks below the surface and miss the poison. Insects be- [175] longing to this class must be combated by what are known as contact insecticides and the spray must come in direct contact with each insect. Spraying in all cases must be thorough and cover all parts of the plant, this being especially necessary with sucking insects as every one must be individually treated in order to be exterminated. Insect reproduction is so rapid that if a few escape unharmed they will soon cover the plants again with their progeny. In bad attacks several successive sprayings are required before the plant is freed entirely from the pest.

Not all animal life in the garden is harmful. Toads, for instance, eat large quantities of insects and never hurt the plants. Lady bugs are also friends of the gardener and seem to be especially fond of plant lice or aphids. Birds rank high in the work of destroying insects, many species feeding almost entirely on insects during a large part of the year. Among the most useful may be cited the swallow, bluebird, robin, kingbird and woodpecker.

Earthworms are beneficial in a different way, they do not eat insects but help to aërate the soil by means of their tunnels which they burrow through the earth to a depth of 6 or 8 feet; then, too, they eat quantities of soil which, in passing through their bodies, is acted [176]