Gyrinus substriatus

5-7.5mm. Generally all black but with yellow legs. The tarsal claws on the mid and hind legs are not darkened and generally the same colour as the legs. It has a prominent lip on the lateral edge of the pronotum that then creates a groove along the inner edge.

Gyrinus marinus is a similar size but has darkened claws on the mid and hind tarsi, lacks the rim and groove on the edge of the pronotum and the elytral rim widens slightly after the mid-point.

Your specimen should have these features:

• 5-7.5mm
• all black body, yellow legs, orange prosternum
• mid and hind tarsal claws same colour as the legs (ie, not darkened)
• a lip and internal groove on the lateral edge of the pronotum
• the elytral rim is more or less parallel along its full length

Found in pools and ponds.

Best seen from March to November.

This whirligig beetle is active during the day, and is often found in large numbers, whirling around on the surface of the water; when disturbed they are able to dive to safety. They carry an air bubble around with them on the tip of the abdomen, which is periodically replenished, and enables them to stay submerged for long periods. During autumn, the adults fly at night in search of new ponds. In July and August the larvae undergo pupation on land, protected by a cocoon of plant matter and sand grains; the adults emerge 10 days later. Both the larvae and adults are predatory, taking prey such as mosquito larvae and other aquatic invertebrates.

Common and widespread in Britain.

Frequent in Leicestershire and Rutland. There were approximately 80 VC55 records for this species up to March 2015.