Pest Beetles
Description: These rose pests vary in size and description as well as genera and species. All have one thing in common: Both the adults and the larvae chomp on your roses and other landscape ornamentals.
Since proper pest identification is necessary to proper control, here are some brief descriptions and photos to help identify your enemy.
- Japanese Beetle (Popillia japonica) - approximately ¼ - ½ in. (6 - 13 mm) long, head and pro-thorax greenish bronze with green along their side, white hair tufts along sides of abdomen and wing covers. Predominately found on the coastal areas of the North American continent, particularly in the more temperate zones.
- June or May Beetle (Phyllophaga sp.) - cousin to the Japanese Beetle. Most species are brown, but some in northern zones are green. Slightly larger than the Japanese Beetle.
- Rose Curculio or Rose Weevil (Asynonychus sp.) - small, snouted beetle about ¼ in. (6 mm) long, reddish black in color.
- Rose Chafer (Macrodactylus subspinosus ) - cousin to the Japanese Beetle; mostly found on the eastern coastal areas of the U. S., ½ in. (13 mm) long, reddish brown head. Birds are sometimes killed eating the adult form of this critter.
- Cucumber Beetle (Diabrotica sp.) - the two most common species are the striped and spotted, ¼ - ½ in. (6 - 13 mm) long, usually light green or yellow with black or tan stripes or spots.
Biology: Lifecycles vary. In general, the female lays eggs in the soil which hatch into larvae. Some, however, lay their eggs in the buds. The larvae vary in size and shape. Some, like those of the Japanese and June beetles, are easily distinguished by their C-shaped bodies - a critter we commonly call "grubs". Others like the Corn Rootworm, the larva of the Cucumber Beetle, are not so easily distinguished. All the larvae feed on roots and other organic materials in the soil. Eventually, the larvae pupate, emerge as adults and the process renews.
Damage: The entire plant is susceptible both by the adult and the larva. The Japanese Beetle will leave skeletonized leaves much like your grandmother's lace doilies. Others like the Rose Chafer, decimate buds. The Rose Curculio's damage may even look like the results of powdery mildew. And the Cucumber Beetle just likes to nestle in your blooms chomping away at the petals.
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