Tuesday, August 9, 2016

Colorado Potato Beetle

Colorado Potato Beetles (Leptinotarsa decemlineata) are endemic to Colorado as well as a few neighboring states where they feed on native plants in the genus Solanum. These include horse nettles and nightshade. With the expansion of potato, tomato, and eggplant crops these beetles made a natural jump from their native host to these cultivated, garden favorites in the same genus. With this expansion in the cultivation of food crops in the genus Solanum this beetle also expanded it's reach and now can be found throughout much of the United States and parts of Canada.

They are considered to be a serious pest of potato, tomato, eggplant and pepper crops and their feeding habits can drastically reduce yield or even kill the plants. Because of this potential harm to food crops people are often dependent on insecticides to control them. Unfortunately, this beetle shows an extraordinary ability to develop resistance to insecticides developed to control it. This falls in line with what I have been saying for years and have mentioned numerous times in various posts on this very blog. Insecticides only work for a short period of time, before the insect you are targeting develops resistance and passes that resistance onto their offspring. Within a few generations they will have nearly complete resistance to the chemical cocktail and your spray will have no ill effects on them. Then you have the added concern of the spray you are using causing the unintended death of beneficial bugs like bees, butterflies and ladybugs. Insecticides are not pest specific. They routinely kill all insects they come in contact with. Care should always be exercised when using insecticides, and always follow the directions to the letter. Using more than is necessary causes more harm than good and can actually cause the resistance to insecticides to be exacerbated exponentially.

Larva feeding on potato
CPB overwinter as adults and become active again in the spring when the temperatures warm up. They will feed on weeds, volunteer potatoes and other volunteer plants within the genus Solanum. About 3 or 4 days after feeding they will mate and within days of mating the female will begin laying clusters of up to 24 eggs on the underside of the leaves of the host plant. I've read differing accounts of how many eggs they can produce in their short window of 4 to 5 weeks of ovipositing. Some say 400-500 and still others claim they may lay up to 800 eggs. Whichever number is correct, they obviously lay a tremendous amount of eggs and are quite adept at populating an area where food sources meet their needs.  It takes up to 9 days for the eggs to hatch, depending on how warm the temperatures are. Within 3 weeks they will burrow into the ground to form a pupal chamber and remain there for up to 10 days before emerging as adults. These new females will feed for a few days and seek out mates and the cycle begins again. There may be up to 3 generations per year. With such prolific reproduction it is no wonder there are so many and they can quickly become pests.

Colorado Potato Beetles are also known by other names such as Potato Beetle, Ten-lined Potato Beetle, Ten-Striped Spearman, and Colorado Beetle. They measure up to 1/2 inch in length (or 30 mm)....and their wings are yellow-orange with 10 dark brown stripes. They are often confused with the False Potato Beetle. The false potato beetle has a distinctive brown stripe down the center of their wings. The false potato beetle and the Colorado potato beetle are not able to cross breed. The Colorado potato beetle is the only one considered a pest.

We are familiar with unwanted 6 legged invaders in the United States that have made their way here via cargo shipments from other countries. Think Mutlti-Colored Asian Lady Beetle, or the Japanese Beetle, and a whole host of other destructive little blighters. The Colorado Potato Beetle is native to the US, but has spread it's reach to include Asia, and Europe. It is spreading exponentially and could end up in northern Africa, as well as Japan and other nearby countries sooner rather than later. With so much travel and trade taking place across all borders and with so many different countries its no wonder the entire World experiences an onslaught of 6-legged menaces. Truthfully it's a wonder there isn't more of a problem than there is.

If you find your garden being invaded by this hungry little bug it can be very frustrating. There are options available for organically controlling it, or you can manually remove them from the leaves. Rotating the area where you grow your crops each year can also help control them. Just keep in mind any chemicals you use may not work long term as they are notorious for building up resistance to most all chemicals designed to kill.


  1. Haven't had any problem with them lately, but it can be hard to hand pick them if you had lots of taters.

  2. We haven't had an issue either but I like the idea of organic control. Great images!