Water beetle (Laccophilus poecilus)

KingdomAnimalia
PhylumArthropoda
ClassInsecta
OrderColeoptera
FamilyDytiscidae
GenusLaccophilus
SizeLength: 3 mm

Classified as Vulnerable in the UK.

This attractive little water beetle has a pattern of pale markings on its wing cases. It was previously known at under three different names: Laccophilus variegatus, L. obsoletus and L. ponticus. Like all the members of its family, it is well adapted to underwater life. As well as having the head sunk into the thorax, their hind legs have become flattened and equipped with hairs to aid with swimming. The whole animal is beautifully streamlined, and their breathing apparatus is designed for maximum efficiency. However, their links with their terrestrial cousins is obvious from the fact that all members of the family are strong fliers.

This species is widely distributed around Europe, ranging from southern Scandinavia to the Mediterranean. In the UK, however, it is now found only on the Lewes Levels in Sussex, although it was once more widespread. There are records for southeast Yorkshire, Kent and south Hampshire, as well as East and West Sussex. It was found on the Pevensey Levels until 1972, and it is believed to have disappeared from there through a decline in water quality.

This beetle is found in lowland fen and coastal grazing marsh, but does not favour brackish water. It is associated with the well-vegetated margins of ditches and lakes, often with common water starwort and mare's-tail flanked by floating sweet grass.

Not a lot appears to be known about the behaviour of this rare beetle. It is believed the adults emerge in July and survive through the winter until the following March. Both adults and larvae are fierce carnivores, in common with the rest of their family, although the larvae feed by injecting digestive fluids and sucking the prey dry. The adults feed in the conventional way, masticating their prey with the well-developed jaws.

It is thought that the greatest threat to this water beetle is a loss of water quality and a lowering of the water table.

Laccophilus poecilus is listed in the UK Biodiversity Action Plan (UK BAP), and is included in English Nature's Species Recovery Programme. The first thing is to ensure that the beetle is not lost from its only known site in the UK. The second is to establish the beetle's true status, and survey known former sites to find out whether there are any specimens surviving, or if the habitat is suitable for a re-introduction programme.

The UK BAP Species Action Plan is available at:
http://www.ukbap.org.uk

Information supplied by English Nature.

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