Insects (Maine Cranberries) - Red-headed Flea Beetle
Order: Coleoptera || Family: Chrysomelidae
Scientific Name: Systena frontalis (F.)
[first noticed this pest at two sites in 2009–heavy outbreak at 1 of those sites; increased to three sites as of the 2010 season, with fairly high numbers at 2 of the 3 sites; found them at the vast majority of sites in 2014 at very high numbers, throughout Sept.]
Last photo shows characteristic leaf-feeding injury by the adult beetles
Action Threshold for flea beetles: There is no ‘firm’ or full-proof threshold for this pest, probably because the adults can be very patchy on a bed, but…if you are averaging sweepnet counts of 15 or more per 25 sweeps, they consider that (in Massachusetts) high enough to consider taking action against them. A high level of beetle feeding can significantly impact bud development the following season. Since the beetles can be so patchy, be sure that you don’t just sweep one portion of a bed (make sure you have good representation of the entire bed). If you are still getting 15 or more beetles, across the entire acreage, I would certainly be concerned and trying to control them would be justified.
General Notes: Adult Red-headed Flea Beetles feed on the the undersides of the leaves, while usually leaving the top leaf surface intact. But they also gouge the berries, and overall, their feeding can significantly impact bud development for the following year if their populations are high.
Description: As visible from the photos above, they are small insects (3.5 to 5 mm long), and are shiny and mostly black; there is a slightly reddish tint to their head that is visible when you look closely or especially when the sun catches it (see the 3rd photo above). Notice, too, their thick hind legs, which look a little like small grasshopper legs. This is what makes them good jumpers, and hence is the source of the ‘flea’ that’s part of their name, but they can also fly as well.
Life Cycle: There is only a single generation per year. They overwinter in the egg stage and although the eggs hatch reportedly in May (probably not until June for much of Maine), the adults don’t begin to show up on cranberry beds until late in July (or sometimes later). The adults remain on the beds for a couple of months, feeding, mating, and, when the time is right (late August – early September), laying their eggs, which are deposited just beneath the soil surface. Populations of the adults are often very patchy.
[see also pdf Fact Sheet out of Wisconsin]
Control: For specific and current control recommendations for Maine for this pest, please refer to the Maine Cranberry Pest Management Guide.
Cranberry questions? Contact Charles Armstrong, Cranberry Professional. University of Maine Cooperative Extension || Pest Management Office || 491 College Avenue || Orono, ME 04473-1295 || Tel: 207.581.2967 [email: charles.armstrong@maine.edu]
