By Adam Varenhorst
An additional soybean defoliator to monitor this week is the redheaded flea beetle. These beetles get their name due to the distinct red-brown colored head, which stands out on their otherwise shiny black bodies (Figure 1-A). Furthermore, flea beetles have specialized hind legs that enable them to jump long distances, like fleas. The redheaded flea beetle is one of the larger flea beetles that may be observed in South Dakota crops.
Figure 1. A) Redheaded flea beetle adult. B) Small holes from redheaded flea beetle feeding. Courtesy: Adam Varenhorst.
In general, flea beetles are defoliators that eat small holes on leaves (Figure 1-B). 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).
Figure 2. Soybean defoliation chart. Courtesy: Marlin E. Rice.Source : sdstate.edu