Flea beetle
Scientific name: Epitrix cucumeris, Systena blanda
Identification: Feeding damage consists of numerous “shot-holes,” 1–5 mm in diameter.
Flea beetles are small (2–3 mm long), shiny black beetles. Adults are active and jump when disturbed.
Biology: Flea beetles in Ontario generally have one generation per year. The lifecycle from egg to adult may take as little as 7 weeks, making a second generation possible in some years. Adult flea beetles overwinter in leaf litter. They emerge and begin feeding in mid-May. Adults lay eggs near the roots of host plants throughout the spring and early summer. Larvae develop on the roots. In late July, adults emerge from the soil, feed and then seek hibernation sites in the fall.
Period of activity: Adults emerge and begin feeding on young plants in mid-May.
Scouting notes: Begin monitoring for flea beetles as soon as the transplants are set in the field.
Thresholds: For plants less than 8” tall, a treatment threshold of more than 4 adults per 30 plants may be used. This is based on inspecting groups of three plants at ten sites in the field.
Management notes: Small plants in less-than-ideal growing conditions are more likely to be affected by flea beetle feeding. Most plants are able to outgrow the damage.
If thresholds are reached and feeding damage is outpacing plant growth (generally in cool conditions when little growth is occurring), insecticide treatment may be warranted.
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Tom Klein, Some Rights Reserved. Licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.
Whitney Cranshaw, All Rights Reserved.
