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Wood-Boring Beetles & Weevils

Introduction:

There are 6 main wood-boring beetles/weevils commonly found in the UK.

It is the larval stage of the insect which bore through the wood leaving unsightly holes and this is what is commonly known as 'woodworm'.

Leaving infected wood untreated can lead to significant and extensve damage hich can be very expensive to recify.



Common Furniture Beetle (Anobium punctatum):

These are a small brown beetle about 2.5 - 6 mm in length, they are usually chocolate brown in colour but this can vary.

These beetles can fly well but most found flying tend to be males.

A female will lay around 20 to 60 eggs, with the average being about 28. These are laid in small groups of 2-4 which are wedged into cracks and joints in the wood.

When the larva emerges it eats through the bottom of the egg shell and enters the crack where the egg was laid, it then bores into the wood.

The larva grows to about 7mm in length and is greyish white in colour, the larva do not emerge from the wood and spend the whole of the larval stage within the wood.

When the larva is mature it constructs it's pupal chamber directly beneath the wood surface. The pupa looks like the adult beetle but is creamy white in colour and soft. The pupal stage lasts for around 6 to 8 weeks.

The total length of the life-cycle probably averages between 3 - 4 years.



Death Watch Beetle  (Xestobium rufovillosum):

These beetles are much larger than the Common Furniture Beetle about 7mm in length. Females are usually larger than the males. They are dark greyish-brown with a pattern of yellow hairs.

Death Watch Beetles rarely fly, but they are well-known for the 'tapping' noises they make which is caused by their heads tapping on the wood.

A female will lay 3-4 eggs on the surface of rough wood, these eggs are sticky and whitish ovals in appearance. The average number of eggs for a female is 40-60.

The larva look similar to the Common Furniture Beetle larva but whereas the latte have been laid in a crack, this is not the case for the Death Watch Beetle Larva, these move about on the surface of the wood until they find a suitable crack or old flight hole and start to bore into the wood.

The larva grow to about 12mm and the frass they produce can easily be seen by the naked eye.

The Pupal stage is very similar to the Common Furniture Beetle except they are larger in size.

The length of life-cycle is variable but an average is about 4-5 years.



House Longhorn Beetle (Hylotrupes bajulus):

This beetle is a member of the Cerambycidae family, almost all members of which are wood-borers. 

The males are not much larger than 6mm but the females can up up to 25mm in length. They are greyish black or dark brown-black in colour and have two greyish marks on their wing cases.

The eggs are laid in small groups in cracks and crevices in the wood. A single female can lay up to 200 eggs in a lifetime.

The larva can reach a length of 24mm and start at the surface of the wood, only boring deeper as hey grow. It has been possible to hear the larva eat as their jaws scraping the wood can be quite clear during warm weather.

Pupation usually takes place in May each year, although it has been known to occur in Autumn of even Winter and the pupa are approximately 25mm long.

The total life-cycle is usually 3-6 years but the majority of this time is spent in the larval stage.




Powder Post Beetle (Lyctus brunneus):

Although 6 species of Lyctus occur in the UK, Lyctus brunneus is by far he most common species.

These are a long cylindrical beetle and vary in length from about 2 to 7 mm. They are a chestnut brown colour, but darker specimens can be found.

The female deposits he eggs into the pores of the wood with a long egg-laying tube. Several eggs can be deposited in the same pore.

The larva hatch and tunnel following the grain of the wood at first but as it grows the boring pattern becomes more random. The larva reach a size of about 5mm.

When the larva have finished feeding they construct a largish pupal chamber close to the surface of the wood.




Wharf Borer (Nacerdes melanura):



The adult beetle can vary in length from 6-12mm. It has the appearance of a rather 'soft' looking insect and is a golden brown colour, with black tips to the wing cases.

They are strong flyers and are native to North America, it is not known when they first entered the UK.

Wharf Borers only attack wood which is wet and they are commonly found in harbours where they bore into pilings. They can also be found in damp cellars.




Wood-Boring Weevils (Euophryum confine, Euophryum rufum, Pentarthrum huttoni):

These are typical weevils with long cylindrical bodies and long 'snout'. they vary in length from 2-5mm. E. confine is blackish brown to reddish-brown and P. huttoni is more blackish in appearance. 

The female bites a hole into the wood and deposits he eggs. The larva eats the whole of the egg prior to boring into the wood, where it continues to live and grow until it is about 3.5mm long. The larval stage lasts 6-8 months.

The larva pupates for about 16 days, after which a new adult emerges. The adult lives for about 16 months.







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