Hazel pot beetle (Cryptocephalus coryli)

Description

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Hazel pot beetle fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Hazel pot beetle description

An orange and black insect that has the typical - if slightly squarish - 'beetle' shape. The thorax is black in males and red in females, and the wing covers are reddish-orange fringed with black. The whole beetle is very glossy.

Size

Body length: 10 mm

Hazel pot beetle biology

Adult beetles emerge around mid-May to mid-June. Females lay their eggs whilst perched in low foliage and they cut leaves from the tree, which are thought to act as food for their ground-dwelling larvae. Each egg is held between the hind legs and a 'pot' is made around it with the beetle's own droppings. This 'pot' is then dropped into the leaf litter under the bush and, after the larva hatches, it feeds on the fallen leaves. The larvae continue to add to the pots for themselves from their own droppings, and this is thought to act as a defence mechanism. When danger threatens the larva retreats into its pot in which it also over-winters. However, they are also vulnerable to predation by wood mice.

Both adults and larvae eat hazel leaves or birch leaves, showing a preference for birch when this is available. The larvae may take between one and two years to reach maturity.

Hazel pot beetle range

Once formerly widespread in southern England as far north as Lincolnshire in as many as ten counties. Since 1970 it has been found in only three sites, one each in Berkshire, Lincolnshire and Surrey. The species occurs in several other European countries and it is regarded as threatened in most of those countries for which a statistical assessment has been made.

You can view distribution information for this species at the National Biodiversity Network Gateway.

Hazel pot beetle habitat

Adult hazel pot beetles are almost always found on birch or hazel bushes though not usually large trees. They seem to prefer south-facing scrub margin, or isolated bushes in hot, dry places to those growing in dense scrub or shady woods. In the northeast Midlands, it is found on birch scrub in heathland, whilst in Berkshire and Surrey, it is occurs on birch and hazel on warm, south-facing hillsides of calcareous grassland.

Hazel pot beetle status

Classified as Endangered in the UK.

Hazel pot beetle threats

It is not entirely clear why the hazel pot beetle has become so rare although destruction of its habitat has certainly been a threat. Research by Leeds University has shown that neither adult nor larval beetles disperse very far, rarely going more than 50 metres from their nursery areas, even though the adults can fly. Genetic research has shown very little gene flow between neighbouring populations, indicating that fragmentation of the beetle's habitat, and hence of populations, it the main threat to this species.

Hazel pot beetle conservation

English Nature added the hazel pot beetle to its Species Recovery Programme in 1995. The first task in the programme was to discover more about numbers remaining, their life-cycle and why they are so rare. A PhD studentship project was set up at Leeds University in 1999 to study the ecology of this beetle and a number of related species. In partnership with Leeds University and the Lincolnshire Wildlife Trust, English Nature is also embarking on a captive breeding and establishment programme.

One of the first releases of captive-bred larvae took place at Whisby Nature Park in Lincolnshire in November 2000. Because it is difficult to trace the progress of the larvae on the ground, they were tagged with small pieces of stainless steel to enable tracking using a metal detector. This was followed by releasing adults and further larvae at both Whisby and another Lincolnshire site in 2001. This has proved very successful, with adults found mating and laying eggs within 10 minutes of release. A Lincolnshire entomologist, Annette Binding, has undertaken much of the behavioural research on the hazel pot beetle.

There may be further information about this species available via the National Biodiversity Network Gateway.

The UK Biodiversity Action Plan for this species is available at UK BAP.

Authentication

Information supplied by English Nature.

http://www.english-nature.org.uk

Glossary

Calcareous grassland

Containing free calcium carbonate, chalky.

Larvae

Stage in an animal's lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.

Thorax

Part of the body located near the head in animals. In insects, the three segments between the head and the abdomen, each of which has a pair of legs.

References