The Colorado potato beetle is a leaf beetle that is THE major pest of potatoes. They can also be to a lesser extent a pest of eggplant. The adults are 3/8th of an inch long yellowish in color, with black stripes on their back with a dark orange head. The eggs laid by the adults are orange clusters, typically on the undersides of the potato leaves. The larvae do the majority of the damage by eating the leaves of the potato plants. If left unchecked the larvae will completely defoliate a potato patch.
The Colorado potato beetle is a super bug. It is resistant to ALL chemicals controls. In the past when I sprayed chemicals, I tried some pretty harsh products on the potato beetle larvae, and I tried some of the botanical or organic insecticides such as BT and pyrethrins, and nothing fazed them even in the slightest. This is the main reason that I am against spraying any insecticides. When you spray an insecticide, it kills the majority of the insects you want to kill, along with the insect predators you do not want to kill. In time the pest will recover, typically faster than the predator, and with an increased resistance to your chemical of choice. Then you are constantly spraying to keep in check the pest populations that would have naturally been kept in check by beneficial insects if given the appropriate habitat and time to appear. Remember, the predators always follow the prey, so there is a lag time when the pests are present and the predators have yet to come to the rescue. If you spray, then you never give these beneficial bugs a chance to do their job. The pests never become resistant to predator insect eating them.
Colorado potato beetle larvae
Tips for Colorado potato beetle control
1. Practice polyculture. I grew my potatoes surrounded by leeks, onions, and broccoli. I had zero potato beetles. When I had my potato beetles in rows, I smashed hundreds of them.
2. Don’t grow your potatoes in grocery store rows, and mix in a good mixture of companions with your potatoes.
3. If you are growing eggplant, you would do well to keep them away from your potatoes.
4. Experiment with different varieties of potato. When I grew my potatoes in rows, my “German Butterball” potatoes were filled with larvae, while my “Blue” potatoes had very few larvae.
5. Scout and hand pick them. This is actually effective if you do this daily. It takes me about ten minutes to go through my patch, but I don’t pick them off, because it takes too long. I put some old gloves on, and I crush them as I go. This is about three times quicker than picking them off, especially when they are small. I would suggest wearing eye protection though, I once was squirted in the eye with larvae guts. (Since I've been growing them in a polyculture, I did not hand pick at all!)
Keyhole Garden (Potatoes, Brassicas, Onions, Leeks)
~ Phil Williams
Phil Williams is a permaculture consultant and designer and creator of the website foodproduction101.com. His website provides useful, timely information for the experienced or beginning gardener, landscaper, or permaculturalist. Phil's personal goals are to build soil, restore and regenerate degraded landscapes, grow and raise an abundance of healthy food of great variety, design and install resilient permaculture gardens in the most efficient manner possible, and teach others along the way.