Insects attacking the potato
One of our most commonly cultivated field and garden crops, the potato, is frequently attacked by insects of one species or another. Although the foliage is most frequently injured, damage to the stems and tubers is not at all uncommon. Fortunately, most of the insects attacking the leaves and stems of the plants can be easily controlled if remedial measures are taken early. But, as is true in the case of all injurious forms, the best results can be expected only if insecticides are applied as soon as the insects appear. In planning control operations it should be borne in mind that insects, according to the manner in which they feed, may be divided roughly into two classes, namely, biting or chewing insects, and sucking insects. The former, in feeding, actually chew pieces out of the leaves and can, therefore, be killed by coating the surface of the foliage with a stomach poison such as arsenate of lead. The latter class, on the other hand, suck the juices from the plant by means of a sucking tube inserted into the tissues. They must be fought by a contact poison, as, for instance, nicotine sulphate, which kills the insects when it comes into contact with their bodies. Stomach poisons have no controlling effect on sucking insects. To assist the grower in identifying the insects attacking his potato vines, a key has been prepared. A key to insects commonly found feeding on the tubers precedes the chapter dealing with those species.