Redheaded Flea Beetles Clipping Corn Silks

Figure 1. Small holes from redheaded flea beetle feeding. Courtesy: Al Heying

Written collaboratively by Adam Varenhorst, Amanda Bachmann, Philip Rozeboom, Patrick Wagner, and Brad McManus.

Originally Submitted: July 24, 2023

While scouting corn last week, we noticed large populations of emerging corn rootworms, but also populations of redheaded flea beetles. These defoliators are removing leaf tissue, but not at levels that warrant treatment (Figure 1). Often in corn, redheaded flea beetles will only strip a layer of the leaves off, which results in windowpane holes. The bigger issue with redheaded flea beetles is that they will feed on corn silks.

Identification

Figure 2. Redheaded flea beetle adult. Courtesy: Adam Varenhorst

Redheaded flea beetles get their name due to the distinct red-brown colored head, which stands out on their otherwise shiny black bodies (Figure 2).

Flea beetles have specialized hind legs that enable them to jump long distances, similar to fleas.

Scouting

In corn, redheaded flea beetles will feed on the silks (Figure 3). This can lead to reduced pollination and ears that are not filled out. If you are observing defoliation and redheaded flea beetle populations, examine the silks.

Figure 3. Redheaded flea beetle feeding on silks. Courtesy: Al Heying

Treatment may be necessary if there are more than five beetles on a single ear, the silks are clipped within one-half of the tip of the husk, and pollination is less than 50% complete.

To determine if thresholds have been reached, examine 10 plants from 10 areas within the field (100 plants total).

If corn rootworm beetles are also observed on the ears, they will also contribute to silk clipping.

Management

If significant silk clipping is observed please refer to the most-current edition of the South Dakota Pest Management Guide: Corn.