Acorn weevil

An acorn weevil, with an incredibly long rostrum, standing on an acorn

Acorn weevil © Frank Porch

Acorn weevil

Look out for this weevil on oak trees, where females lay their eggs inside acorns.

Scientific name

Curculio glandium

When to see

Usually April - October

Species information

Statistics

Length: 4.1 - 6.7mm (excluding the rostrum)

Conservation status

Common

Habitats

About

The acorn weevil is usually found on or around oak trees. Females use their long snout (called a rostrum) to make a hole in a developing acorn. They then lay eggs inside the acorn – typically just one or two eggs per acorn. The larvae live inside the acorn, feeding on it. When the acorn has fallen to the floor, they chew their way out and bury themselves in the ground. They'll spend at least three winters underground, before eventually emerging as an adult in spring.

How to identify

A mottled brown, rather oval-shaped weevil with a very long rostrum and long antennae. Females have a much longer rostrum than males. The eyes are large and flattened. The scutellum (the patch at the base of the wings, in the centre of the body) is square or wider than long. There is a tooth on the underside of the front femurs. There are several similar species that can be hard to identify.

Distribution

Found across much of England as far north as Yorkshire, but less widely distributed in the southwest. Scattered distribution in Wales.

Did you know?

The female acorn weevil has the longest rostrum of any UK weevil.