Cobweb Beetle - Ctesias serra


The common name relates to the habit of the larva of taking trapped insects from spider webs. The adult beetle is dark brown in colour and rarely seen in its natural habitat, so this beetle is more commonly recorded as a larva.

Identification difficulty
Recording advice

Unless identified by a recognised expert, a photo is required. If the photo doesn't show the key ID features then in the comments box describe the size and identifying characters you have observed.


The preferred habitat is beneath old, thick bark.

When to see it

All year round.

Life History

The larva of Ctesias serra lives in crevices and under the bark of ancient trees, feeding on the left-over meals of spiders. The hairs are part of its defence mechanism against attack by spiders - thrusting them forward when threatened.

UK Status

Widespread, particularly in the southern half of Britain.

VC55 Status

Occasional in Leicestershire and Rutland.

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Leicestershire & Rutland Map


Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2020+ | 2015-2019 | pre-2015

UK Map