Published on July 10th, 2013 | by Jami Scholl
Organic Pest Control for Flea Beetles
Flea beetles are small, black little pests that infest your beautiful garden. These tiny insects jump like fleas when disturbed, hence the name. They live throughout North America and adore munching on most vegetable crops. They will happily eat their way through your garden and will only stop to munch on you– which I learned about the hard way! I tried slapping my hands together in a leaf sandwich to smash them before they hopped to who-knows-where. I wasn’t too successful– although the action ensured that I will always be known as the crazy person talking angrily to the tiny bugs hopping around her.
If you’ve met flea beetles in your garden, you understand the frustration.
Flea beetles are some of the most difficult pests to control organically. Should there be a day when you walk into your garden to see that it suddenly looks like it has been machine gunned by a mouse, then you can be certain you’ve flea beetles. The adults chew small holes in plant leaves while the larvae feed on the plant roots. This insect is most damaging to young plants and may cause the death of many varieties.
Unlike using chemical herbicides and insecticides that kill EVERYTHING in the garden, which leads to an imbalanced ecological system, organic gardeners need to learn about each particular pests to interrupt their life cycles. Flea beetles over-winter in the leaf litter and woody brushy areas surrounding the garden site, and when temperatures reach 50ºF degrees they emerge from the soil to feed in the grassy areas right next to the garden or field. The lady flea beetles will soon lay their eggs in the soil next to these plants, and the eggs will hatch in one to two weeks. These larvae feed on the plants until fully grown, at which point they return to the soil to pupate for between 11 to 13 days when they emerge as adults that attack your precious garden.
Yellow sticky traps or counting the numbers of beetles you see on plant leaves will let you know if you have a flea beetle problem. Two beetles on a young plant of three leaves or less is the maximum or 5 on a plant with four or five leaves are the maximum that you want to see, otherwise you are over the threshold of what your plants can tolerate.
Flea beetles are most active in spring and especially love eggplant, potatoes, peppers, tomatoes, spinach, melons, and young plants from the cabbage family: broccoli, Brussels sprouts, cauliflower, cabbage, collards and kale. The cabbage family of crops of Asian origin are also favorites of the flea beetles for the lack of oil on the leaves, making them easier to hold onto and munch. If you like Chinese cabbage, tatsoi, mizuna, turnip, mustards, bok choi, radish, arugula or red Russian kale, then you need to think about how to protect your crops.
There are many organic pest control methods that work to prevent or decrease flea beetle populations, such as trap cropping, delaying planting until after the overwintering beetles have emerged (thus reducing their food supply and decreasing the population), insecticidal soap, neem, natural pyrethrin, kaolin clay (Surround), pesticide containing spinosad (Entrust), hot pepper or garlic sprays, and nematodes. Nematode formulations can be applied to the soil and attack beetle larvae reducing the numbers of adults that will increase the next cycle of adult beetles. Nematodes are usually available at garden centers. The native braconid wasp is another natural control, where the wasp uses the beetle as a host, thus sterilizing the female wasp while developing, and kills her upon its emergence. By using a commercial insecticide like Sevin to wipe everything out, the braconid wasp is also killed. Hence the beauty of organic gardening – balance is desired.
However, floating row covers may be the best protection. But a word of caution when using floating row covers – these are best used where no susceptible crop was grown the year before, otherwise you’ll trap the insects in with your food as they emerge from the soil. Be sure that the covers are continuous and securely covered by placing soil around the perimeter of the cover to keep it firmly sealed to the ground.
After weeding replace the floating row cover ASAP. If you do find a few beetles after a few days of re-covering, control them with one of the organic methods listed above and then re-cover. Check back a few days later, as organic management of a garden is about control, not complete massacre.