Every Spring around the first of May, my garden gets an infestation of flea beetles which chew those tiny pin-holes in my arugula, mesclun mix, radishes and other such greens. I've tried row cover, but it heats up the bed so that my crops bolt too early. Last year I resorted to using a rotenone/pyrethrum spray, but I really don't want to do that again as it will kill beneficials as well--though it is organically acceptable. Has anyone tried using a hand-held vacumn cleaner on the little beasties? Ideas anyone??
Dr. Cranshaw, who wrote it, told my Master Gardener class that flea beetles are the toughest insect for the organic farmers he works with. He hasn't found a method he is completely happy with, either.
You may already know this - but row covers come in different weights that allow different ratios of light transmission or heat insulation. You would want one with the least insulation value, and here in Colorado I would probably use a shade cloth suspended over that.
Last year I had them on flowers. I vacuumed them, it worked okay (vacuum works better on squash bugs). Plan on cleaning your vacuum and/or changing the bag and filter afterwards - beetles will make the exhaust smell bad.
This year I'm interplanting catnip with the zauschneria (mild infestation) to see if I can get them to move on to a trap crop (nasturtiums, radishes) that they like better.
Many thanks for your input here, pollengarden! Sounds to me that a multi-pronged approach is my best bet--using every method possible. I can start with the row cover, then use organic insecticides, and keep the vacumn handy. And...hope for the best!