A look at spotted beetles

A look at spotted beetles


Posted 6th Jul 2017


Following Buglife Scotland's rediscovery of the Six-spotted pot beetle and the Ten-spotted pot beetle, we take a look at the fascinating insects

Pot beetles have a truly amazing life cycle. Their larvae spend most of their lives inside a pot which is actually made of their own droppings, providing them with the perfect camouflage and protection from predators.

Nearly all of the UK's 19 species of pot beetle are rare, while the Six-spotted and the Ten-spotted pot beetles are Endangered. Threats to the beetles include habitat loss and changes in woodland management, with the UK's remaining small isolated populations vulnerable to fires, flooding, disease and overgrazing.

They also have something of a quirky life cycle - after laying her eggs, the female pot beetle will hold them in her back legs, spending time covering them with a waxy coating and some of her own droppings, in a process called 'scatoshelling'.

This can take up to 10 minutes per egg, but it's time well spent as it has been shown to deter predators. If the female happens to be disturbed while laying an egg, she will abandon it without coating it. In such an instance, they are far more likely to be eaten by ladybirds, lacewings and other predators than a coated egg would be. Once she has coated the egg, she lets it drop to the ground from the leaf or flower head she is sitting on.

Once the larvae has hatched, they stay within their protective egg-case, feeding on fallen leaves from food plants. The larvae enlarge the neck of their pots as they grow, using their own droppings. Beetle larvae lack the hardened wing cases of the adults, so the pot will act almost like a snail shell, providing protection and camouflage. Despite this, it seems the predation of larvae is high, with ground beetles and small mammals such as wood mice taking a large number. Pot beetle larvae will feed on leaf litter under the host plant, but will sometimes eat fresh leaves later in their development. Larvae of some species can take up to two years to completely develop, where upon they seal up their larval cases and pupate, emerging as adult beetles a few weeks later.

Information courtesy of Buglife Scotland / Scott Shank

Image courtesy of © Scott Shanks





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