The Colorado Potato Beetle, also known as a potato bug, is a common insect pest found primarily on potatoes in North America. This destructive insect devours the foliage (and blossoms) on potato plants and can strip them bare in a few days if action isn’t taken. Fortunately, there are ways you can keep potato bugs under control. Find out more about the Colorado Potato Beetle and what you can do to protect your potato plants from damage.
What is the Colorado Potato Beetle?
The Colorado Potato Beetle (Leptinotarsa decemlineata) is hard-shelled beetle that attacks members of the nightshade family, such as potatoes, tomatoes, and peppers. Its preferred host plant is the potato plant. While the adult beetle does relatively little damage to potato plants, the larvae devour the leaves and can defoliate your potato plants.
How do they get into my potato plants?
The most common way potato bugs get to your potato plants is from overwintering in the soil and emerging in the spring at about the same time your potatoes send up sprouts and begin growing. However, that is not the only way Colorado Potato Beetles can find their way to your potato plants.
Adult Colorado Potato Beetles have wings and can fly into your garden. According to the University of Nebraska’s Cropwatch, potato bugs will fly several miles searching for host plants. That means if you live near a field or farm where potatoes were grown the previous year (and were infected with potato bugs), emerging potato bugs may fly to your garden in the spring in search of food.
Potato bugs may fly to your garden from neighboring gardens at any time during the summer. Likewise, even if you practice good crop rotation in your garden, potato bugs emerging in one section of the garden in the spring may fly to another garden area in search of potato plants to devour.
What damage can they do to my potatoes?
The adult Colorado Potato Beetle does little damage to potato plants, but when it lays eggs, the developing larvae will devour the foliage on your potato plants. The larvae may strip the stems and branches of all their foliage with a severe infestation. Without leaves, potato plants cannot perform photosynthesis and manufacture food for the plant. Without a food source, tubers will not form under the ground either.
Iowa State University explains that young potato plants can survive if they lose up to 30 percent of their foliage. However, as the plants mature, they are more sensitive to the loss of foliage. Large potato plants cannot sustain a loss of more than 10 percent of their foliage.
Can I remove the Colorado Potato Beetle from my potatoes?
Colorado potato beetles can be difficult to control unless you catch them early. There are several ways to get rid of them. Which methods work for you depends on how many potato plants you are growing, the extent of the infestation, and whether you are willing to use chemical pesticides in your garden.
If you are growing a few potato plants handpicking the potato bugs and dropping them into a bucket of soapy water is an effective way to keep them under control.
Check the plants daily for any signs of the Colorado Potato Beetle, using care to check the undersides of leaves for eggs, too.
Adult beetles are typically seen on the upper leaves of the potato plant but may be under the leaves too.
Larvae attack the tenderest leaves first and can often be found in clusters of new leaves, and may even attack potato blossoms.
- Home Remedies
Mixing a tablespoon of dish detergent and a couple of tablespoons of vegetable oil in a spray bottle filled with water makes an excellent (and safe) spray to kill potato bugs. However, the spray must thoroughly coat the potato bug to be effective. This clogs the breathing pores and kills the potato bug.
This spray is not effective as a foliar spray and has no residual effect for killing potato bugs. If you try this home remedy, shake the bottle before every use to thoroughly mix the ingredients and spray it directly on the potato bugs to saturate them.
Colorado Potato Beetles are resistant to many pesticides, especially those in the Great Lakes Region and along the east coast, says Cropwatch. The pesticide carbaryl is effective in killing Colorado Potato Beetles. The pesticide Sevin contains carbaryl and is available as a powder for dusting the foliage or as a liquid for use in a sprayer.
According to the National Pesticide Information Center, over 190 registered pesticide products have the active ingredient carbaryl. Choose a pesticide that lists carbaryl as the active ingredient for the best defense against Colorado Potato Beetles.
Always follow the directions on the label to avoid accidental exposure or ingestion of pesticides and store them out of the reach of children and pets.
How can you prevent getting potato bugs the following year?
- Treating potato bugs up until harvest.
It may be tempting to stop battling potato bugs in the garden once your potatoes have matured and the tops have begun to die back, but now is not the time to be lax. Potato Beetle larvae drop to the ground and burrow in the soil to pupate and overwinter.
Ignoring the potato bugs in the late summer and fall will allow them to overwinter in your garden soil, where they will emerge in the spring and begin the vicious cycle all over again.
- Keep weeds away from the garden.
Colorado Potato Beetles love potatoes, but they live on weeds in the nightshade family, too. Keeping the edges of your garden weed-free will prevent potato bugs from making themselves home on tasty weeds and reproducing freely near your garden.
- Rotate your crops.
Planting your potatoes in a new location yearly will help prevent an infestation from overwintering potato bugs. As a rule, you should not grow potatoes again in the same area for three years.
- Dig a trench.
Some farmers plow trenches between areas where potatoes have been grown and the new planting location when they are adjacent. This method may be effective if you are growing a large plot of potatoes. Here’s how to do it.
- Dig a trench at least a foot deep with sides sloped between 45 and 90 degrees.
- Line the trench with plastic.
- Cover the plastic with a thin layer of soil.
Because new potato bugs emerge from the soil in the spring and walk to find a host plant, many will walk into the trench and be unable to walk out again. It won’t prevent all the potato bugs from reaching your potatoes, as some may choose to fly, but it will reduce the number of Colorado Potato Beetles that reach your new potato plants.
Battling potato bugs can be challenging, but you don’t need to let them destroy your potatoes. Checking your potato plants frequently and taking quick action with the techniques mentioned above dramatically improves your chances of keeping them under control.