Long-horned beetles: Watch out for the stunning insects which wildlife experts love and fear in equal measure

There are over 20,000 species of long-horned beetles worldwide! Concern is because some of these often large beetles have larvae which feed on live wood and therefore are serious pests of timber trees and so upset commercial foresters, and others may damage structural timbers in old buildings.

However, our excitement is in equal measure because many of these insects feed on dead, rotting wood where the larvae munch away on fungal hyphae. Some of these beetle grubs are very specific about where they occur and under what conditions and often are very rare. Indeed, these beetles are what we call ‘indicators’ of ancient wood-pastures like for instance, Chatsworth Park with its great veteran trees. For the informed and skilled ecologist, these insects can tell us about the continuity of rare habitat on a site over many centuries and about the rarity and condition of the trees too. Plenty of dead wood both standing in the tree canopy or fallen to the floor, provides habitat for different and distinctive fungi, lichens, slime-moulds, and insects like rare hoverflies and of course, the long-horned beetles.

Sometimes these adult beetles emerge from logs brought into homes and gardens as fuelwood. Present as larvae they have pupated and then emerge into your home. I will return to this behaviour in a later article.

Some species are very closely tied to ancient woods and wood-pastures like grand parklands and are rare. Others like the Wasp Beetle pictured here by Julie Smith of Whitwell, still require dead wood but are more widespread and ubiquitous. Furthermore, they will travel from a woodland with dead timbers to nearby hedgerows or gardens to feed on nectar-bearing flowers which is what the adult beetles require. Both common hogweed and cow parsley are good places to look on a sunny day. Another similar species that will come to gardens is the orange and black Strangalia beetle. Log-piles in the garden help conserve these stunning insects.

Professor Ian D. Rotherham is a researcher, writer; broadcaster on wildlife; environmental issues and is contactable on [email protected] ; follow Ian’s blog here and Twitter @IanThewildside