Tomato leaf damage

Credit: Carolyn Herriot

The damage is caused by adult flea beetles (Chrysomelide). In B.C., you’ll most commonly find the Colorado cabbage flea beetle (Phyllotreta albionica), hop flea beetle (Psylliodes punctulatus) and tuber flea beetle (Epitrix tuberis).

The insect is hard to see since it is slightly bigger than a pinhead, usually black, brown or bronze. It has well-developed hind legs and when disturbed jumps like fleas. The juvenile forms – white, legless grubs with brown heads – thrive in soil but are rarely seen; they do not cause noticeable damage except in potato tubers where the larva produce thread-like tunnels that eventually fill in with corky brown tissue.

Flea beetles overwinter as adults among protective debris in the soil, emerging in spring to feed and lay eggs. There are between one to four generations per year. Some types are very host-specific to the nightshade family (Solanaceae) or cabbage family (Brassicaceae), while others are more broad ranging in their feeding. Seedlings are very susceptible, while older plants have a better chance of surviving.

To control flea-beetle damage to your plants:

• Avoid planting too early in the season.
• Apply row cover over plants for the first three to four weeks.
• Overseed and thin to the strongest survivor thereby minimizing flea-beetle damage.
• Plant a “trap” crop, such as Indian mustard (Brassica juncea var. crispifolia), bok choy or pak choy. Flea beetles are lured to these plants and do not bother other cole crops.
• Use yellow sticky trap for monitoring.