Potato Beetles

This year we have planted Red Maria, Yukon Gold, and Kennebec potatoes. They are up and growing. The predator we need to watch for this time of year are Colorado potato beetles.

Potato beetles have four stages, three that we watch for: eggs, larva, and mature adults. First we will see the adults. They are a hard-shelled insect. They mate, then the female lays yellow eggs on the underside of the leaves. These hatch into red larva, which eat the potato leaves. As they mature they get larger, but are still red. Eventually they drop and burrow into the ground and form a chrysalis? which then hatches into a mature adult.

We fight these insects several ways. First we change the field where we have our potatoes (rotating our crops). Beetles that have wintered over from last year will still hatch and will find at least some of our potato plants. Moving the potato location means that less plants get found.

Then we look for potato beetles, eggs and larva at least twice a week. We mash the eggs and drop the larva and adults into soapy water. If we start soon enough, we will see adults and eggs the first week, then eggs and larva the next week, and finally by the third or fourth week larva and adults. The more adults and eggs you can find at the beginning the lower the larva infestation.

I think that I counted 8 beetles on this plant. You can see parts of leaves that have been eaten away. But this isn’t bad. However, if they aren’t contained, they can eat all the foliage of the potato plants. This mean that you don’t have a good potato harvest. And we have had that happen in the past. Right now we have a very small infestation. Hopefully it will stay that way!

Here is an extension sheet that talks about potato beetles in more detail.