I had tiny black bugs all over my chard this summer. They're deep in the base of the plants that are still in the garden (raised beds). Last year I at...
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tiny black bugs #222217
Asked December 10, 2014, 10:31 AM EST
I had tiny black bugs all over my chard this summer. They're deep in the base of the plants that are still in the garden (raised beds). Last year I ate chard from the garden well into the new year and wanted to do that this year, but would it be better to take all the chard out, since it's pretty well infested? Is there anything I should/could do to the soil to keep them from coming back when I re-plant in the spring? Thanks!
Benton CountyOregon
Expert Response
The flea beetle is a the probable culprit and the following exerpt from the PNW Handbook give suggestions for control. Our hot, dry summer did allow bugs to proliferate and removing the current plants may help, but the description below of how they overwinter will be important to understand. If you cut them down to the base you may get another crop that is generally bug-free this spring. Good luck!
Pest description and crop damage
Flea beetle adults are metallic greenish brown to black in color and
from 0.06 to 0.12 inch long. They derive their name from their
well-developed hind legs; when disturbed, they jump like fleas. The
larvae live in the soil, are slender, whitish, and about 0.25 inch long
when mature. Adult beetles chew small holes in leaves, giving them a
sievelike appearance. The cotyledons of emerging seedlings are
especially susceptible to damage. Larvae feed on underground parts of
the plant. High populations of flea beetles feeding on seedling plants
can result in stand loss. Foliar damage to mature plants is not
considered to be damaging economically. Flea beetles contribute to the
spread of various plant diseases.
Biology and life history
Most flea beetle species have similar life cycles. Adults overwinter
in trash around field margins. They become active in late March through
May. Flea beetles lay their very small eggs in May in the soil around
the plant, on the leaves, or in cavities hollowed out in stems. The
larvae feed on the foliage, mine the leaves, or attack the roots,
depending on the species, usually from June to mid July, when pupation
in the soil occurs. Adults emerge from July through early September and
feed a short time before overwintering in trash around field margins.
Depending on the species, there are one or two generations each year.
Thanks. This is very helpful. Before getting your response, I almost sent a follow-up email indicating they look like fleas! Do I need to apply insecticidal soap to the soil to help avoid a re-infestation in the spring when I plant new starts, since the information indicates the fleas could over-winter?
I don't think the soap would necessarily kill them in the soil. Some strong pesticides like the ones listed in the article might, but assuming you don't want to put those in your soil I would suggest that you improve the soil/fertility and that will make
the plants stronger to fight it off. We used to have a regular problem with the flea beetles (they still show up every year on the newly growing plants but I ignore them and the plants generally overcome the first infestation) but I think as we have improved our garden soil and added mulch the plants are more vigorous and able to overcome the fleas. And the weather changes the picture also, and you can't do much about that!
