Colorado Potato Beetle Refresher

Marissa Schuh, Horticulture IPM Extension Educator

Up to this point in the growing season, potatoes have been looking great. Colorado potato beetles haven’t caused too many problems yet, but we all know what these beetles are capable of.  Let’s do a rundown of Colorado potato beetle management.

The first flush of Colorado potato beetle activity is the emergence of overwintering adults, who feed and lay eggs. Photo:  Jack Rabin, Rutgers NJ Agric. Expt. Station, Bugwood.org.

Non-chemical Controls

• Trials on Minnesota farms have found that flaming, trap crops, and trenching didn’t really work. 

• 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). 

• Mulches seem to make it harder for adults to reach plants, and for larvae to bury into the soil to pupate.

• 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 of it all)

• 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.

Up to this point in the growing season, potatoes have been looking great. Colorado potato beetles haven’t caused too many problems yet, but we all know what these beetles are capable of.  Let’s do a rundown of Colorado potato beetle management. 

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.  This time of year, we can be seeing adult beetles who have emerged from their winter hiding spots, the eggs they’ve laid, or small larvae.  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

As long as defoliation is kept below 10%, yields shouldn’t be harmed. Easier said than done, but helpful to keep in mind.

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. Created with BioRender.com