Colorado Potato Beetle Refresher

Marissa Schuh, Horticulture IPM Extension Educator. Originally published in 2023, revised 2026.

Spring is here: flowers are blooming, birds are singing, and as soon as our potatoes emerge from the soil, Colorado potato beetle will follow. We all know what these guys are capable of (complete defoliation), let’s do a rundown of Colorado potato beetle management.

The first flush of Colorado potato beetle are the overwintering adults, who lay the eggs of the next generation. Photo:  Jack Rabin, Rutgers NJ Agric. Expt. Station, Bugwood.org.

Non-chemical Controls

• Rotation: If you have a larger farm or are growing in multiple spots, this is the most effective non-chemical control. Overwintered Colorado Potato Beetle adults walk from wherever they spent the winter to the potatoes they want to eat. The further we rotate, the more die on their trek.
• Delaying planting: This strategy starves out the overwintering adults, who die before they can find a food source. This only works if we have the right potato variety and a long enough season for the potato to size up before the fall.
• Traps crops: Plant potatoes you don't intend to harvest earlier than your main crop, and between wherever last year and this year's potato crops are. Colorado potato beetles reach this spot first, get distracted, leaving the potatoes you intend to harvest alone and allowing you to do aggressive management in your trap crop. You will still need to manage the Colorado potato beetle in this trap crop, so this is not a one and done solution (though nothing is for this pest). You can hear more about farmer experiences with trap crops in this YouTube video.
• Trenches: This is paired with rotation, and often trap crops. A trench is dug, often with equipment like discs, then lined with plastic.  The overwintering adults waddle into the trench, fall down, and bake in the sun/starve.  In reality, it doesn't always work this neatly, and when trialed on Minnesota farms, the results were underwhelming. 
• Flaming: If you already have a flame weeder, a similar setup can be used as part of your Colorado potato beetle management regime. When plants are less than 4 inches tall and have Colorado Potato beetles on them, you flame them. A standard setup for this has two burners facing the base of the plant per row. The short burst of heat is, in theory, enough to kill the beetles but not your plant (that seed piece has a lot of energy, and the stress of recovering is less than the stress of being defoliated by beetles). In some trials, this practice kills 80% of the beetles, but it doesn't always go this well. You can hear about farmer experiences with flaming in this video.
• Row covers: Our old friend row covers can be helpful in protecting very small plants (assuming where you are planting isn’t full of plant debris that are housing overwintering adults). Again, you can hear about farmers experiences with row cover in this video.
• Mulches: Mulches seem to make it harder for adults to reach plants, and for larvae to bury into the soil to pupate. 
• Physical squishing and removal: Eggs can be squashed, and larvae and beetles can be removed from plants and killed in a variety of emotionally cathartic ways (soapy water, gallon plastic bags left in the sun, I've heard it all).
• Biological controls: There are insects that feed on Colorado potato beetles. It doesn’t seem like they are hungry enough to make a major dent, but they are present doing work. Don’t forget about protecting these insects when using insecticides.

A spotted ladybeetle eating Colorado potato beetle eggs. Photo: Whitney Cranshaw, Colorado State University, Bugwood.org

Using Insecticides

Colorado potato beetle is one tough bug. They’ve handily evolved resistance to over 50 insecticides, and this has happened in Minnesota, on organic farms. Do not rely on just one insecticide in your Colorado potato beetle (*cough* spinosad *cough*), rotate your insecticides. For product recommendations, check out the Midwest Vegetable Production Guide. The guide can quickly give you the modes of actions of different products, so that you can use different products effectively.

Scout to confirm what life stage and size of the Colorado potato beetles on your farm before making any applications. Larvae are the most susceptible life stage to insecticide treatments, and the smaller the larvae are, the better products are going to work. Focus sprays on the small larvae to get good efficacy while also making a dent in potato beetle populations early in the season.

Small, recently hatched Colorado potato beetle larvae are the easiest to kill with insecticides. Photo: C. Trouvé, Service de la Protection des Végétaux, Bugwood.org

Depending on what you find, consider treating if...

• 10% leaf defoliation
• Adults: 25 beetles per 50 plants scouted
• Small larvae (about 1/8 inch or less in size): 4 larvae per 50 plants scouted
• Large larvae (closer to .5 inches long): 1.5 larvae per plant or stem, based on a count of 50 plants

These number can shift quickly -- if eggs hatch, for example, the number of larvae on a plant can quadruple. Scout every 3-4 days.

Putting it all together

The below graph gives you at a glance management tactics based on time of year and Colorado potato beetle age.

Graphic and illustrations by Marissa Schuh.