This is the second year that I have planted a garden. I had a few of the Colorado Potato Bugs (brown & white striped with brown heads)last year. However, this year they totally stripped my potato plants and are now working on the tomato plants. Even eating the tomatoes themselves. I read on the internet that they were very resistant to insecticides. I have tried different powders and sprays this year. Nothing helped. Can you advise on how to try to get rid of these pesky bugs? Thanks for your advice.

In their adult stage, these insects are about 3/8 inch long, yellow orange in color with dark-brown or black stripes running lengthwise down their backs. The larvae are fat, red or yellow grubs with two rows of black dots down their backs. Larvae will tend to congregate on the undersides of leaves. Egg masses will be yellow-orange laid in neat little rows on leaf undersides.

This pest can devastate plantings of tomatoes, peppers, and eggplant and of course potatoes. The adults and larvae destroy plants by devouring foliage.

The beetle originated in the Rocky Mountains, spreading eastward in the late 1800’s as potato plantings increased, reaching epidemic proportions. Adult beetles that have over wintered in plant debris lay their eggs in yellow masses on the undersides of leaves as the first potato leaves emerge from the ground. The larvae that hatch then feed for a couple of weeks, drop to the soil, pupate and emerge as adults that feed and lay more eggs. This lifecycle is completed in about a month and there can be as many as three generations per growing season.

The Colorado potato beetle is an excellent example of Darwinian adaptation or “survival of the fittest”. Over time they have developed resistance to insecticides. So it can seem that nothing is effective against these pests.

Culturally, make sure that you use good sanitation so that adults can’t over winter in plant debris. Rotate crops so that you aren’t planting Nightshade family members in the same spot year after year. Use a thick layer of straw mulch around plantings. You could also try growing a fall crop of potatoes to avoid the peak potato beetle populations.

One of my organic gardening references says that flax, horseradish, garlic, marigolds, or green beans are repellant plants to use as companion plants.

The search and squish method of control will help, but can be time consuming in large plantings. You can try alternating sprays of Bacillus thuringiensis San Diego strain with Pyrethrins or another insecticide of your choice.