Wood Boring Insects in Brittany & Normandy

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Wood Boring Insects in Brittany & Normandy

There is a variety of wood boring insects found in houses and buildings in northern and northwestern France (Normandy and Brittany). Some, if kept under control, present no danger while others require professional extermination and have the capacity to destroy the structural wood in a house.

Note: Many people misuse terms to describe insect infestations. The term “woodworm” is often used as a generic name for any wood boring insects. It is in fact, more correctly, the Common Furniture Beetle (see below).

Most commonly found in the region, from the least dangerous:

There are certain varieties of beetle in Brittany and Normandy which infest timber with their larvae without causing a serious problem. The beetle creates small, dart-like holes in the wood (active ones have sawdust trails coming from them), and are very common - every home has some. They are seldom a problem and the wood stays strong unless the infestation is enormous. Each year the flying insect lays eggs in the existing holes, the worm burrows in, pupates and then flies off. 

Treatment: spray or brush on several coats of an appropriate treatment available from DIY shops. You can choose between white spirit- and soap-based products. Use protective equipment and a proper mask during application. Where the structural wood is visible, apply several coats of lasure after treatment as this normally contains insecticide and fungicide which helps to block the entry holes and kill any eggs or larvae. (Lasure is a coating specifically for structural timber).

Vrillettes: common furniture beetle or  powderpost beetle

• Vrillettes (fr): annobium punctatum (common furniture beetle) or lyctus brunneus and lyctus linearis (powderpost beetle)

These beetles create larger, round holes. They are small red-brown beetles (2 to 6 mm) which, when in their larvae (worm) stage, make medium sized round holes in wood (1 to 2 mm). You may find dead beetles and grainy or smooth, cream coloured sawdust under attacked areas. 

They require a humidity level of approximately 10% to reproduce so are most often found in ground floor skirting boards, cellars and roof spaces where there is some humidity. They are able to eat through a vast amount of wood, causing it to crumble. They are also attracted to white or light painted woods, so ensure that the edges of your window frames are well sealed. They are most active late March to August, especially in warm weather. 

Treatment: if the attack is not too extensive then it can be treated in much the same way as woodworm. If the attack is severe, wood will have to be removed and (ideally) burnt. Larger timbers can benefit from injection treatment, particularly joist ends which are built into walls and can therefore be damp. Painted timber is often extensively damaged behind the paint and should be removed.

Capricorne: house longhorn beetle

• Capricorne (fr): hylotrupes bajulus (house longhorn beetle)

This beetle is found in the sapwood of nearly all softwoods and some hardwoods, especially structural roofing timbers. Adults can reach 25 mm in size, are black/brown in colour and have patches of grey hair on the back. They are active from July to October especially on warm days. Larvae are up to 30 mm long and hence eat a lot; you can actually hear them when active. The distinctive feature is that the holes in the timber are large (7 to12 mm) and OVAL. If you find these, a complete inspection of all structural timber by an expert is essential. 

Treatment will involve spraying but also injection under pressure. The beetle can attack structural timber, substantially, until it crumbles – that would be your first knowledge of its presence.

Termites: reticuliterms santonensis

Altogether a different type of attack. Termites are rather like giant ants living in colonies, usually underground. They climb through the structure of the house creating galleries behind plaster and systematically eating every morsel of timber. The adult breeding members of the colony fly and swarm as ants do, but the physical difference is that the ant’s antennae are kinked, the body has a distinct waist and the front wings are larger than the back wings. 

Treatment: termites must be treated and eradicated with professional assistance. The soil around and under the property must be included in the treatment. In France, the treatment company must be correctly certified. There are grants available to help with up to 40% of the cost of eradication. All confirmed cases of termite must, by law, be reported immediately to the nearest Mairie by recorded delivery post with confirmation (recommandé avec accusé de réception).