House Longhorn beetle

The House Longhorn beetle (Hylotrupes bajulus) is a wood-boring beetle known for its voracious appetite for softwood timbers.  

Where is the House Longhorn beetle found?

The beetle occurs almost exclusively in North West Surrey, however it is sometimes found in London.

What damage do they cause?

The House Longhorn beetle principally feeds on the sapwood of softwood roofing timbers. As with most woodworm, it is not actually the beetle itself that causes most of the damage. The majority of the timber degeneration comes from the larvae of the beetle (hence woodworm). The adult beetles do, however, cause all the visual damage as they bore exit holes in the timbers.  

Once you see these exit holes there is probably already extensive damage inside the timber. In fact there is often very little wood left inside the beam. The structural deterioration caused by the House Longhorn beetle is rapid and hazardous.

Life cycle of the House Longhorn beetle

The House Longhorn beetle spends the majority of its life as larvae. It lays its eggs in wood crevices. In two to three weeks the larvae hatch and begin to bore into the wood. For the next three to eleven years the larvae eat their way through the timber.  

The transformation into a beetle occurs over about three weeks. The beetles then eat their way out of the timber and fly off to mate and then lay more eggs. The lifespan for the adults is a mere three weeks. This usually happens in the warmer summer months. Relatively high summer temperatures in Surrey assist the breeding process.  

How to recognise House Longhorn beetles

 

  • Flight holes are 3-9mm in diameter.  
  • Makes oval tunnels.  
  • These holes resemble the holes of the Common Furniture Beetle, except that they are significantly larger.
  • Produces bore dust which is cylindrical and compact.
  • The adult beetle has long antennae or ‘horns’, is brown and black and has two black spots on its thorax.

 

What can I do if I suspect an infestation?

In areas where House Longhorn beetle occurs, pre-industrial timber treatment is mandatory. This species is Legally Notifiable in certain areas as it causes rapid deterioration.

If you suspect an attack, contact Peter Bonfield, Head of Wood Properties, Building Research Establishment, E-mail: bonfieldp@bre.co.uk.

Treatment for the House Longhorn beetle 

The House Longhorn beetle treatment process is difficult. An attack requires much more than the surface treatment that is needed for a standard wood borer infestation.

Usually, woodworm treatments involve a simple application of a surface treatment by brush or spray. This breaks the egg-laying cycle.  

This simple treatment will not work for the House Longhorn beetle. Its propensity to remain deep inside timber and the significantly greater damage it causes over longer period means that House Longhorn beetle treatment requires two additional steps – internal injection and a weekly inspection by an expert.

House Longhorn beetle treatment process

 

  • All loose material must be removed and varnished or painted surfaces must be sanded back.  
  • Drill injection holes into the timber in active areas.
  • Holes must be blown out and injected with Ultra Rapid Timber Paste.
  • Then plug holes.
  • Then apply surface treatment.
  • Inspect weekly for sounds of activity such as ‘munching’.