Colorado Potato Beetle
Commonly referred to as "potato bugs," Colorado potato beetles can do swift damage to the foliage of potato plants. Although the adult striped beetle does not injure the plant, the larva does. Larvae overwinter in the soil, emerging when the potato plant is in full foliage, and quickly strip away the leaves. As they mature, the adults lay eggs on the undersides of leaves and begin the cycle anew. Without quick action, an infestation of potato bugs can defoliate your entire crop of potato plants within a week or two. Hand picking may be a choice if infestation is light or you only have a few plants. Otherwise, use insecticide labeled for Colorado potato beetles as these pests resist many generic insecticides and are difficult to control.
A number of blister beetles and flea beetles may also infest potato plants, eating away the foliage and leaving the plant unable to produce food. Growth may be stunted if the infestation is severe. Use insecticides labeled for blister and flea beetles to combat these pests.
Aphids attack potato plants and suck the juices from the plant. These tiny insects may be difficult to detect. The first sign you notice may be mottled foliage or deformed leaves. Look under leaves and along stems. Use an insecticide labeled for aphids to eradicate these pests as they make your plants more susceptible to other viral diseases.
Both grubs (the larvae of beetles) and wire worms live in the soil and feed on the potato tubers. Although grubs may sever the roots and stunt the growth of the plant above the ground, both grubs and wire worms may feed on the tubers out of sight. When potatoes are harvested, holes may be discovered in the tubers. Treat your soil with insecticides labeled for wire worms or grubs if they are a problem in your area.