Last Saturday I taught a gardening class at the Missouri River Break workshop series at the Montana State University College of Technology here in Great Falls. The topic of potato bugs came up when we were discussing pest control for cheapskates who dont like investing a ton of money into pesticides. One lady said year after year she battles them, often with discouraging results.

Colorado Potato Beetles

What are often called potato bugs are Colorado potato beetles, and they will do a number on the foliage of pretty much anything in the nightshade family, including tomatoes and eggplants.

The tough part is the adults overwinter in the ground in the soil near the potato (or other nightshade) crop. This illustrates another reason crop rotation is an important gardening practice; unfortunately, potato beetles will travel over a mile to find a suitable food source. Rotating one area of the garden is one thing, moving it miles down the road is pretty tough.

Colorado potato beetles are usually one-half inch long sporting black stripes on their yellow backs. The eggs are bright red with a couple of rows of black dots on them, and take a week to ten days to hatch, depending on the temperature during that time.

The adults lay eggs on the underside of the leaves, and this is often the best place to eliminate them. If youve had a problem with them in the past, carefully examine the leaves and wipe off any eggs you find. If you dont catch them when theyre still eggs or newly hatched, the larvae followed by hungry adults will do their damage then oftentimes start another generation. Its the nastier side of the circle of life with your poor potato plants caught in the middle.

Hard to Kill

The reason its important to catch them early is because potato beetles have a notorious reputation for being hard to kill using chemical remedies. These tenacious little beetles often develop resistance to frequently used pesticides, including DDT back in the 1950s. Now thats tough. It appears something will work for a certain amount of time, but if all of the beetles are not wiped out (which is practically impossible) the pesticides lose their effectiveness sometimes within a season.

If potato beetles are an annual problem, you can try planting your potatoes later in the season to hopefully eliminate a food source for adults emerging from overwintering. Unfortunately, if youre growing in a suburb or another populated area this may mean they simply move over to your neighbors potato patch for their meals. Theyre not gone, their just off visiting.

A simple option is to place a floating row cover over your potatoes (as long as theyre not planted in the same area as the prior year) making sure to take down the edges securely so potato beetles cant find their way underneath the fabric. It should keep the bulk of them from landing on the young plants and starting a new cycle. Colorado potato beetles are one of those extremely frustrating pests, but with a little diligence you can at least make a dent in their numbers and reduce the damage they do to your spuds.