Redheaded Flea Beetles Active in Soybean

Black beetle with a red head on soybean leaf.
Figure 1. Redheaded flea beetle adult. Courtesy: Adam Varenhorst.

Originally Submitted: July 8, 2021

Redheaded flea beetles are active in soybean. Although they haven’t caused significant defoliation yet, their activity should be monitored.

Identification

Redheaded flea beetles get their name due to the distinct red-brown colored head, which stands out on their otherwise shiny, black bodies (Figure 1). Flea beetles have specialized hind legs that enable them to jump long distances, similar to fleas. The redheaded flea beetle is one of the larger flea beetles that may be observed in South Dakota crops.

Green soybean leaf with small holes near the center and edges.
Figure 2. Small holes from redheaded flea beetle feeding. Courtesy: Adam Varenhorst.

Scouting

In general, flea beetles are defoliators that eat small holes into leaves (Figure 2). Although these beetles are typically not a serious soybean pest, large populations can result in considerable defoliation.

Since there are also other defoliating insect pests present in soybean at this time of the season, we recommend scouting and using the cumulative defoliating threshold of 20% to determine if treatment is necessary (Figure 2).

Six soybean leaves with varying levels of defoliation.
Figure 3. Soybean defoliation chart. Courtesy: Marlin E. Rice.

Related Topics

Soybean Insects

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