Latin: Lyctinae
This beetle species belongs to the family of lyctinae, where several varieties are found. In Denmark, the naturally occurring species is Lyctidae linearis, whereas Lyctus brunneus is originally a North American species. Lyctus brunneus can be found all over the world, and it is also common in Denmark.
Appearance
The two species are similar in appearance. They are elongated, color vice reddish brown to black. They have two antennae that form a small curl at the end. When the beetles are fully grown, they are 2.5 – 8.0 mm long, at the same time they are slightly flattened. The larvae can be 5-6 mm long, and these are yellowish white in color except the head, which has dark brown jaws and a yellow-brown head.
Biology and behavior
The two species are similar behaviorally vice. The powderpost beetle is a group of wood boring beetles, which worldwide includes 70 species. The common powderpost beetle (Lyctuc Linearis) is especially associated with large pore hardwoods like walnut, ash, and oak. They can live in bamboo and other types of tropical wood. The beetles only attack hard, untreated woods, and they rarely attack wood that is over 10 years old, as they prefer fresh wood.
The females lay up to 50 eggs in the trees pores. When the larva is fully developed, it gnaws below the surface of the tree, and where it pupates. Inside the pupa, the larva transforms into an adult powderpost beetle. The beetle leaves the tree through a small fly hole that is round and diameter vice about 1 mm.
The larval passages are round and 1mm in diameter, they can go all ways into the tree. The drill flour is light, fine, and loosely packed.
Normally the adult powderpost beetles appear from June to August. If the conditions are appropriate, they may already appear during February. Typically, the development from egg to larva to fully grown beetle takes about a year. If the wood lacks starch and the conditions are poor, their development can be extended up to four years.
Damage
The larvae feed on the starch cells in the wood, gradually transforming the wood into fine and talc-like dust with an outer thin shell. The larvae and beetles do not attack the heartwood as there is no starch.
In the recent years, there are a larger focus on the powderpost beetles, mainly because the large pore tropical wood is used for walls, floors, and furniture. When the wood has been dried with heat, before they are shipped out, there is a risk that the wood will be attacked by the beetle.
The larvae can destroy objects in the home completely, and the beetles can spread to other objects of hard, young, and untreated wood.
Prevention and control
To preventing the powderpost beetles, the surface of the wood must be treated. Especially at the end of the wood as it is here the pores are found. Use wood preservatives which is intended for the purpose, in the form that protect against the house buck and borer beetles.
Should the powderpost beetles attack, use the approved wood preservatives. As with the preventive treatment, the product must be suitable for protection against house bucks and borer beetles.
Be aware that surface-treated wood such as lacquered and painted wood does not have the ability to absorb the agent sufficiently. This is because the protective agent can only be sucked up through the fly holes. In such cases, you must repeat the treatment several times – or resort to other control methods.
Another method of control is heat treatment. Here it is important that the wood can withstand heating, as otherwise this form of treatment is not possible. The wood must be heated to a core temperature of around 60 degrees – and this temperature must not be reached in less than six hours. This kills all stages of the powderpost. If there is an attack on smaller objects, the beetles can also be controlled by freezing the object at -18 degrees for 72 hours.
You should always check newly purchased wood products, furniture etc. for fly holes.
"Pests in House and Home"
"Bed Bugs - Bites, Stings and Itches"
"Food Pests"
"Husets dyreliv" (Insects Around the House - Only danish)
"Skadedyr i træ" (Timber Pests - Only danish)
"Stuefluen" (Common Housefly - Only danish)