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 

These are ordered from least to most destructive:

There are certain varieties of beetle in Brittany and Normandy which infest timber with their larvae making small, dart-like holes in the wood (active ones have sawdust trails coming from them), are very common - every home has some - and can exist without causing a serious problem.

Petite Vrillettes: common furniture beetle, powderpost beetle 

• Petite Vrillettes (fr): anobium punctatum (common furniture beetle) 
• Lyctus brunneus and lyctus linearis (powderpost beetle and horned powderpost beetle)

The Petite Vrilette 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). Dead beetles may be found in grainy or smooth, cream coloured sawdust under attacked areas.  They require a humidity level of approximately 10 percent to reproduce so are most often found in ground floor skirting boards, cellars and roof spaces where there is some humidity. 

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 seldom present 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. Options include 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).

• Information and images of the Petite Vrilette: Click here
• Information and images of the powderpost beetles: Click here

Grosse Vrillette (fr): deathwatch beetle

• Grosse Vrillette (fr): Xestobium rufovillosum (deathwatch beetle) 

The Grosse Vrilette are bigger - 5 to 8 mm long - dark brown and create larger, round holes. They require an environment of 22 percent humidity in wood of 22 to 25 degrees centigrade. Beetles 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.

• Information and pictures of the Vrilette beetles (small and large), their larvae and bored holes: Click here (in French)

Capricorne des maisons: house longhorn beetle

• Capricorne des maisons/Coléoptère Cerambycidae (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.

• Further information from Insects-net: Click here (in French)
• Images of the Capricorne: Click here

Termites: Reticulitermes 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).

Further information and images of the termite and damage caused: Click here

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