**Rose Chafers** (*Macrodactylus subspinosus*) are slender, long-legged, yellowish-tan scarab beetles. They emerge synchronously in late spring/early summer. The conflict is **destruction of flowers and foliage**: the adults swarm and feed voraciously on the leaves, buds, and flowers of roses, grapes, tree fruits, and various ornamentals, often congregating in large numbers that cause rapid, severe aesthetic and economic damage.
Taxonomy and Classification
Rose Chafers belong to the Family Scarabaeidae (Scarab Beetles). They undergo complete metamorphosis. The larval stage is a **white grub** that feeds on the roots of grasses and weeds in sandy soils.
Physical Description
Adults are about 10\text{ mm} long.
- **Adult (Key ID):** Long, spindly, reddish-brown legs; yellowish-tan/gray, slender body; covered in fine, yellowish hairs.
- **Larva (Key ID):** C-shaped, off-white grub found underground.
- **Damage ID:** **Skeletonized leaves** and chewed, tattered petals.
- **Conflict:** Agricultural, Ornamental.
Distribution and Habitat
Common in eastern North America, especially prevalent in areas with sandy or light-textured soil (preferred by grubs). Habitat is the foliage and flowers of host plants during the short, intense adult feeding period.
Behavior and Conflict
The conflict arises from their gregarious and voracious feeding.
- **Mass Aggregation:** Adults aggregate on preferred hosts to feed and mate, overwhelming individual plants.
- **Toxicity:** In large quantities, the ingested beetles can be toxic to poultry and grazing animals.
Management and Prevention
Management is **Exclusion and Physical Control**.
- **Hand-picking** or shaking the beetles off plants into a bucket of soapy water, especially in the early morning.
- Using fine mesh netting to cover high-value plants during the 3-4 week period of adult activity.
- Applying insecticidal nematodes to the soil to control the grub stage.
Conservation and Research
Research focuses on developing pheromone traps to predict their emergence and exploring biological controls for the subterranean grub stage.