Cranberry Flea Beetle
Flea beetles are a diverse group of pestiferous insects that can cause damage to a variety of vegetable crops in Wisconsin (1). The cranberry flea beetle, also known as red-headed flea beetle, is a common beetle that feeds on many different host species. It can be an occasional pest in the Midwest on different crops, including cranberries, blueberries, cabbage, beans, beets, corn, and alfalfa (2).
Description and Life Cycle:
Redheaded flea beetles are small (~1/8”) shiny black beetles with a reddish head (3). They have powerful hind legs and jump when disturbed (4). Adult beetles are present from July through September; adults can also be present until the first hard frost. Redheaded flea beetles overwinter in the egg stage in the soil (5,6). Eggs will hatch in the spring (5). Larvae feed on roots and root hairs from June to August. Pupae occur as early as late-June to early August (4) and adults start emerging in July, laying eggs soon after emergence and continuing through August.
Hosts:
This diverse beetle family causes damage on many different crops and individual species of flea beetles get their name from the host plant that they most regularly cause damage to. In Wisconsin, common species specific flea beetles include: crucifer, eggplant, horseradish, potato, spinach, and striped (cabbage) flea beetle (1). The redheaded flea beetle is an occasional pest on and near cranberry marshes. Up to 40 plants have been identified in Wisconsin as available hosts (6). When adults feed on cranberry they have been shown to have a varietal preference; however, many weed species may be more preferred if present (7). Common cranberry marsh weed species include: marsh St. Johnswort, Joe-Pyeweed, smartweed, jewelweed, and hardhack (6).
Damage:
This early season pest can cause damage to young plants (1). The damage caused by this family is similar across species; adult beetles cause the most damage by chewing holes into leaves (4), which creates brown or burnt looking foliage (3). This damage can slow the growth of the plant, reduce vigor, and with excessive injury can kill the plant (4). Redheaded flea beetle is frequently found but at low population levels. If more attractive alternative hosts are not available red-headed flea beetle will feed on cranberry foliage and berries (6). Feeding can have negative effects on the following year’s buds (5). Larvae that emerge in the spring can feed on roots causing root damage; additionally, damage from red-headed flea beetle larvae can be seen from July to August and during this time can sometimes be mistaken as cranberry girdler damage (3).
Methods of Control:
Trap crops can be effective as they can serve as more attractive hosts (4). This approach provides the most benefit until plants are established. Once established plants are more vigorous and in general can outgrow flea beetle damage. Additional effective methods of control include physical barriers, such as row covers or thick mulch, or physical removal (4), such as shaking the plants over a white cloth or using sweep net (8,2).
Citations available upon request.