Every gardener growing potatoes is likely to run into this beetle, as it’s a devastating pest of potatoes. Both the yellow, black-striped adult and the black-spotted, red larvae feed on potato leaves, and can completely consume them thereby greatly reducing tuber yields and even killing plants. The potato beetle can also be a serious pest on tomato, eggplant, and pepper (all also members of the nightshade family); and the damage is typically so severe, the beetle must be controlled.
Understand The Life Cycle
Adult potato beetles overwinter in the soil and emerge in late spring as temperatures rise. They establish themselves on early or volunteer plants, mate, and the females lay orange-yellow eggs on the underside of the leaves. They lay the eggs in bunches of about two dozen, but can lay up to 500 eggs over a month. Eggs hatch in approximately a week, and the larvae begin to feed on the potato foliage. Because they’re laid in bunches, the larvae tend to be found in clumps, and the damage they do can be quick and severe. The larval stage lasts approximately two weeks, and then they burrow in the ground to pupate. In about another week, the adult beetles emerge, and the process starts all over. Depending on where you live, there are typically two to three generations of beetles per year.
Organic Methods of Control
A variety of strategies are generally necessary to control potato beetles, particularly if organic control is desired:
1) Crop rotation is the first and one of the best defenses against potato beetles. By rotating the potato bed every year, the beetles overwintering in the ground (in last years potato bed) don’t emerge into this years potato bed, but instead have to go looking for the potatoes. This may just delay the first beetle attack on the potatoes, but if early maturing potato varieties are used, it’s sometimes possible to grow and harvest them before the beetles ever find them.
2) Mulching with straw has been shown to reduce the beetle’s ability to locate potato plantings, and it creates an environment favorable to potato beetle predators. Since we use the “lazy bed” potato method for growing potatoes, we definitely mulch.
3) Covering with row covers is another method that combined with crop rotation helps prevent the adult beetles from finding the potatoes.
3) Hand picking and destroying the beetles or larvae is also practical for small potato patches. Also, since the eggs are laid in clumps, by carefully watching the bottom of the potato leaves for the orange eggs, it’s often possible to destroy the eggs before they hatch and can do any damage.
4) Organic pesticides such as rotenone or Bt can be used; however, rotenone is quite toxic so should be used with caution. Bt is effective if the beetles ingest it early in the larval stage. Therefore, Bt must be applied when larvae are first seen, and repeated frequently to assure later hatching larvae ingest the Bt.
5) Fast maturing varieties – there are genetically modified potato varieties that commercial growers are using, but I wouldn’t even consider using them in our garden. Instead, there are several varieties of potatoes that mature in just 75 – 85 days, and can develop tubers before potato beetles become serious pests. These varieties include Norland, Redsen, Sunrise, Superior, Caribe, Pungo, and Yukon Gold. Since we live in Northern Ohio, where the beetles emerge later because of cooler temperatures, using one of these varieties is usually a good strategy.
We’ve found that a combination of strict crop rotation, mulching, hand picking and destroying, and using fast maturing varieties has worked in our garden, and we usually have a nice crop of potatoes each year. We particularly enjoy the Yukon Gold and Caribe potatoes, and they’ve been very successful.