| Small round holes in leaves and insects that jump
like fleas are two signs that a plant is infested with
flea beetles. These shiny oval beetles may be black,
brown, bronze, or striped and are only 1/10 inch
long. They quickly leap out of sight when disturbed.
There are several species of flea beetle and while
some feed on only a few closely related plants,
others feed on a wide variety of crop plants. Many
vegetable crops are affected including tomatoes,
potatoes, cole crops (cabbage family), turnips,
radishes, corn, beans, and beets. Flea beetles are
especially attracted to eggplants and plants may be
almost totally defoliated. Flea beetles may also be
vectors for transmission of disease such as bacterial
wilt in corn.
Symptoms and Diagnosis
Since flea beetles are so small and active, it is easy
to miss them. Watch for a sudden burst of jumping
black spots among the leaves. Disturbing the foliage
of the affected plant or of nearby plants may cause
them to jump again. Commonly found in newly
planted vegetable gardens, flea beetles are most
harmful to seedlings. Larger plants are usually able
to withstand damage. A light infestation of flea
beetles is characterized by tiny round pits or holes
in leaves, creating a shot hole pattern. Heavier
infestations may cause bleached or pitted areas,
ragged holes, or even total loss of leaves resulting in
wilted or stunted plants. Although the larvae feed on
roots of the same plants, they usually do not cause
injury. Larval tunneling may sometimes cause
scarring on potato tubers.
Life Cycle
Adults overwinter in the soil and plant debris,
emerging in spring to feed. They lay eggs in the soil
and die by early July. The legless white or gray
larvae hatch in a week and eat plant roots for 2–3
weeks. The larvae pupate in the soil and mature into
adults in 2–3 weeks. There may be more than one
generation a year.
Integrated Pest Management Strategies
1. Transplant large sturdy seedlings. Large
transplants will be most able to tolerate damage.
Monitor plants closely so that pests may be
controlled before damage is severe. When
planting seeds directly into the garden, sow extra
seeds to allow for loss. Growing susceptible
plants interspersed with less susceptible plants
may help.
2. Use row covers on susceptible plants, especially
seedlings and eggplant.
3. Avoid flea beetles.Plant susceptible crops as late
as possible to avoid flea beetles, which are most
active in early spring.
4. Till the soil in fall or early spring. This helps to
remove the weeds and crop debris that provide a
habitat for overwintering adults. During the
growing season, cultivate soil to disrupt larval
habitat and control weeds to prevent flea beetles
from jumping in from adjacent weedy areas.
5. Use white sticky traps to monitor and trap flea
beetles.
6. Use insecticides. Effective products include
rotenone, insecticidal soaps, pyrethrins, sabadilla,
Neem (when registered for food crops),
diatomaceous earth, or permethrin (Eight).
Planting trap crops such as radish and then
spraying those plants can help reduce the crop’s
exposure to insecticide. Predatory nematodes may
be used as a soil drench to control larvae. |
