Written by

Danny Neill

The Ultimate Guide to Treating & Preventing House Longhorn Beetle

The Silent Destroyer Lurking in Our Homes: House Longhorn Beetle

In the lush landscapes of the UK, where history whispers through the walls of its buildings, a silent destroyer works unnoticed, compromising the structural integrity of wooden constructions and threatening the heritage embedded within.

This pest, known as the House Longhorn beetle (Hylotrupes bajulus), has emerged as a significant adversary to coniferous timber structures, from roof trusses and beams to floorboards and doors.

At Platinum Chemicals Ltd, we stand at the forefront of remedial building solutions, armed with a deep understanding and an array of products to safeguard your property against such insidious threats.


Understanding the House Longhorn Beetle (Hylotrupes bajulus):

The battle against the House Longhorn beetle begins with knowledge. This pest, part of the Cerambycidae family, presents a formidable challenge to coniferous timber throughout the UK.


What Do They Look Like?

Adult House Longhorn beetles range in size from 8 to 25mm, boasting a blackish-brown coloration adorned with distinctive greyish-white patches on their wing covers. Another characteristic feature is the two shiny bumps found on the neck shield, setting them apart from other pests. However, the true threat lies not with the adult beetles but with their larvae. These larvae are pale cream, measuring 2 to 3 cm in length and 4 to 6 mm thick, their bodies marked by ring-shaped segments.

Larvae (left) and Pupae (right) of House Longhorn Beetles 


Lifecycle and Breeding Habits

The lifecycle of the House Longhorn beetle is marked by a brief adult phase, lasting just a few weeks during the summer. During this time, their singular focus is reproduction. Females lay eggs in fine cracks within wood, giving rise to larvae that bore into the timber, initiating a destructive residency that can last from 3 to 6 years, and in some cases, as long as 15 years. These larvae feed mainly on sapwood, weakening structures from within until they pupate and emerge as adults, ready to continue the cycle.


Risks and Damage Caused by House Longhorn Beetles

The larvae of the House Longhorn beetle carve extensive frass galleries within the wood, compromising the structural integrity of the infested timber. This damage is particularly insidious due to the larvae’s preference for attacking the inside of the timbers, leaving the exterior surface untouched and making early detection challenging. Often, the full extent of an infestation goes unnoticed until it’s too late, with beams or floorboards giving way under the strain.

The hidden nature of these attacks exacerbates the threat posed by the House Longhorn beetle, making it a formidable enemy to homes and historical buildings alike. With structural integrity at risk, understanding the signs of infestation and the necessary steps for treatment and prevention becomes paramount.

An Adult House Longhorn Beetle



Identifying an Infestation

The stealth with which the House Longhorn beetle invades and damages wooden structures makes early detection challenging but not impossible. Recognising the signs of an infestation is crucial for timely intervention, potentially saving significant structural components from irreparable damage.

The most deceptive aspect of House Longhorn damage is the larvae’s preference for remaining inside the wood, leaving the exterior virtually untouched. Consequently, traditional signs of wood pest infestation, such as visible boreholes or sawdust-like frass, are often absent. However, vigilant property owners and professionals can look for more subtle indicators:

  • Fine Cracks in Wood: The initial entry point for the laying of eggs. These cracks may appear more pronounced over time.

  • Slight Bulging or Warping of Wood Surfaces: As larvae grow, their tunnels can cause subtle deformations in the wood.

  • Hollow Sounds: Tapping on suspected timber can reveal a change in sound, indicating hollowed-out sections beneath the surface.

It's worth noting that by the time these signs are noticeable, significant damage may already be underway. Therefore, consulting with a specialist, they can provide an expert assessment and recommend immediate steps for treatment.

Close  up Image of a Wooden Floor Board Plank Showing Extensive Damage (Exit Holes) Caused By Larvae


Treatment and Prevention Strategies

Once an infestation of House Longhorn beetle is confirmed, immediate action is necessary to mitigate damage and prevent further infestations. At Platinum Chemicals Ltd, we advocate for a comprehensive approach, combining treatment of affected areas with preventive measures to protect unaffected wood.


Eradicating Infestation
  • Permethrin or Boron-Based Wood Preservatives: The most common form of treatment, these preservatives are effective against larvae within infested timber. Applying these preservatives can kill existing larvae and protect the wood from future attacks.

  • Heat Treatment: Exposing infested wood to high temperatures can eradicate larvae without the use of chemicals. This method requires specialised equipment and should be undertaken by professionals.

  • Fumigation: For severe infestations, fumigation may be necessary. This involves enclosing the affected area and introducing a gas that kills the larvae. Like heat treatment, fumigation should only be performed by licensed professionals.

Effective Spray Treatments are Available to Order From Our Woodworm & Rot Hub Page 


Preventative Measures

Preventing House Longhorn beetle infestations is preferable to treating them. Some key strategies include:

  • Regular Inspections: Especially in older buildings or those with previous infestations, periodic checks by professionals can catch new infestations early.

  • Chemical Treatments: Applying wood preservatives, such as the ones mentioned above, to at-risk areas can deter female beetles from laying eggs.

  • Physical Barriers: Sealing cracks and crevices in wood can prevent access for egg-laying.


Platinum Chemicals Ltd: Your Partner in Combating Wood Pest

Understanding the threat posed by the House Longhorn beetle and taking decisive action to protect your property is essential. At Platinum Chemicals Ltd, we are dedicated to providing the knowledge and solutions necessary to combat this and other wood pests effectively.

Our Woodworm and Rot Treatment Hub Page is a comprehensive resource designed to assist homeowners and professionals alike in addressing various woodworm issues, including treatments for fungal decay such as Dry and Wet Rot, Masonry Rot Treatments, timber joist repairs, and more. With a wide range of products, Platinum Chemicals Ltd is your trusted ally in preserving the integrity and beauty of your property.

In conclusion, while the House Longhorn beetle presents a formidable challenge to wooden structures across the UK, with the right knowledge and resources, it is a challenge that can be met and overcome. By partnering with Platinum Chemicals Ltd, you ensure that your property remains safe, secure, and free from the threats posed by wood pests.

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