Thursday, May 22, 2014

Potato Beetles in the Organic Garden

Unfortunately we are not the only species that enjoy a vegetable garden.  Keeping pests under control can be challenging when you refuse to use any chemicals.  My latest nemesis is the Colorado Potato Beetle (Leptinotarsa decemlineata).  The adult beetles are actually kind of pretty with black and yellow stripes.

The problem is that they love to eat potato plants (they will also eat eggplant and tomato leaves).  They don't bother the tubers, but munch away at the leaves and stems which makes it difficult for the potato plants to photosynthesize and produce tubers.  They overwinter in the soil and I was hoping that our cold winter put a damper on the population, but that doesn't seem to be the case.  They lay eggs, which are yellow-orange and can be found on the underside of leaves.

The red larva, with black heads, hatch add devour the potato leaves as they grow.  When they reach maturity, they go into the soil and a few days later emerge as an adult.  The cycle repeats up to three times in the South because of our long growing season.

So what's gardener to do about these potato beetles without using pesticides?

Strategy 1:  When I saw the first larva on the plants, I sprayed them with a hot pepper spray (1 quart of water, 2 tbsp hot sauce, 3-4 drops dish soap).  I found that this took out maybe half of the larva and did not phase the adults.

Strategy 2: My next attempt was simple, but more tedious.  I took a jar of soapy water and went hunting for potato beetles, larva, and eggs.

It is really important to remove as many eggs as possible.  I have found that they tend to be on the underside of lower leaves.  I also found that eggs were laid on nearby weeds as well, which is yet another reason to keep the beds cleared of weeds.

So far this strategy seems to be working.  I check the potato plants at least once a day and pick off any adults, larva, and eggs.  While hunting for potato beetles a ran across a little baby toad.  Hopefully this little guy will help me out and eat lots of pests!  It's also a reminder of why I don't use chemicals in my garden - I'm not the only one that would be exposed to them.

The potatoes have some leaf damage, but seem to be fine and one just flowered.  Hopefully there will be a nice potato harvest in my future.

Future strategies:  Next year I plan to use a row cover over my potatoes to keep the potato beetles off the plants.  It is really important to move the potato bed to a location that did not previously have Solanaceae crops (potatoes, peppers, eggplants, and tomatoes) since the beetles overwinter in the soil.  It would be pointless to put up a row cover over the same area and have it filled with potato beetles that overwintered in the soil!

Has anyone else battled the potato beetle and found strategies that work?  If so, please share!

This post is shared at Green Thumb Thursday at Grow a Good Life.


  1. I guess that is one good thing about not growing any nightshade crops. I don't have to deal with potato beetles. I used to get a different kind than you have. And they loved the tomatillos.

    1. I guess that's one strategy to avoid them! They've never seemed to bother my tomatoes or peppers. Although now I'm concerned that if I cover the potatoes, they'll just go after something else.

  2. I really liked your photos of all the different life phases of the potato beetle! Very helpful to be able to recognize it when it's still in the egg phase. I'm visiting from Green Thumb Thursdays.

  3. I have only grown potatoes once before and didn't have the beetles. This is my second attempt so hoping for the best. Sounds like you have yours under control and your potatoes will be okay! Nancy

  4. I am going to have to go check out my plants now that I can recognize them before the damage is already done. Thank you so much for sharing on Green Thumb Thursday. I hope you swing by again today.