**Kelp Beetles** (family Staphylinidae, genus *Cafius* is common) are small, predatory rove beetles found exclusively in coastal marine environments, often associated with the same decaying matter as Kelp Flies. The adults and larvae are active predators and scavengers that inhabit the dense mats of decaying **kelp wrack** that washes ashore. They are a beneficial part of the coastal food web, helping to manage other insect populations in the kelp and acting as decomposers. They pose **no conflict** to human structures, agriculture, or health.
Taxonomy and Classification
Kelp Beetles (Rove Beetles) belong to the order Coleoptera. They undergo complete metamorphosis. Rove beetles are characterized by their elongated body and their short wing covers (elytra) that expose most of the abdomen. The adults are highly mobile and often seen rapidly running across the kelp surface. They are part of the unique ecosystem supported by the decomposition of marine algae.
Physical Description
Adult Kelp Beetles are slender, black or dark brown, $1/4$ to $1/2$ inch long.
- **Appearance (Key ID):** Typical rove beetle appearance with short elytra and a long, flexible abdomen.
- **Movement:** Fast-moving, active predators. When disturbed, they often raise the tip of their abdomen defensively.
- **Location:** Found running on the kelp wrack, under decaying mats, or near the high-tide line.
- **Diet:** Predators of other invertebrates (especially kelp fly eggs and larvae) and scavengers of decaying kelp.
Distribution and Habitat
Kelp Beetles are found on temperate coastlines globally. Their habitat is restricted to the beaches and intertidal zones where kelp wrack accumulates. They require the moisture and organic matter provided by the decomposing seaweed.
Behavior and Conflict
The conflict is minimal; they are beneficial insect controls and scavengers.
- **Predation:** They are natural enemies of the nuisance Kelp Fly larvae, helping to keep their populations in check.
- **Decomposition:** They aid in the recycling of nutrients from the marine environment back into the coastal ecosystem.
- **Human Conflict:** They do not bite, carry disease, or damage property. They are simply part of the beach ecosystem.
Management and Prevention
Management is entirely focused on conservation.
- **Conservation:** Chemical control should be avoided on beaches, as it would destroy this beneficial predator and contaminate the marine environment.
- **Toleration:** They should be tolerated on beaches as they are an indicator of a healthy coastal ecosystem and provide a natural control for other insects.
Conservation and Research
Kelp Beetles are managed as an essential element of coastal biodiversity. Research focuses on their role in regulating kelp fly populations and understanding the complex food web of the kelp wrack ecosystem.