Latin: Nacerda melanura
The wharf borer beetle belongs to the genus Oedemeridae, and the beetle is especially encountered along the Danish coasts and around the port cities. The wharf borer beetle is also called by its Latin name Nacerda melanura.
There is a reason for the beetle’s name with maritime associations. Because it is not only in Denmark that the beetle prefers to settle in coastal and port areas. The beetle is widespread in similar places throughout the temperate zone, where the wharf borer beetle is spread through shipping. The wharf borer beetle is thought to have originated in the United States, where it lives in areas around the Great Lakes.
Appearance
An adult wharf borer beetle measures between 1 to 1.5 centimeters in length. The color of the beetle itself is a reddish-golden color, while its coverts are black. The legs are black on the inside and yellow-red on the outside. Sometimes the wharf borer beetle is confused with a wooden buck, as it has correspondingly long feeler horns.
The larva of the wharf borer beetle has a whitish-yellow color and can grow 2 to 3 centimeters long. The larva has characteristics that make it different from many other beetle larvae. It has 3 pairs of well-developed feet at the breast area, just as it has warts on the third and fourth hind body joints.
Biology and behavior
If you want to see the adult wharf borer beetles, the chance of encountering them is greatest in the period from May to October. When the female searches for the perfect environment for her to lay her eggs, she goes exclusively for dead wood. The female most often prefers conifers such as pine, but deciduous trees can also be used for this purpose.
Her larvae must live off the wood inside the tree. Therefore, the female has high demands in regard to the quality of the wood. Among other things, it is important that the wood does not dry out while the larvae are inside the wood. And the larvae also seem to thrive best if the tree is affected by a rot fungus and is generally moist.
This is also the reason why the larvae of the wharf borer beetles prefer wood and timber, which are sometimes sprayed with water and thus keep the wood moist. However, the wharf borer beetles cannot live in wood that is constantly covered with water.
The larvae dig wide chambers in the tree that follow the veins of the tree. They do not make passages or tunnels, which is otherwise the custom for most of the tree-drilling larvae. Their development from larva to adult wharf borer beetle lasts between 1 to 3 years, depending on the conditions in the tree.
Damage
There is no doubt that wharf borer beetles can do great damage if they attack in the wrong places. It can for instance be an extremely difficult task if the beetles attack basements in houses located on framed wooden poles (piloting). And if the attack is large, it can be an impossible challenge to fight the wharf borer beetles. It may therefore be necessary to replace the piles, which may ultimately result in greater economical expenses.
Prevention and pest control
If the wharf borer beetle attacks wood and timber, it is a clear sign that the wood is damp. In the case of building timber in a house, it is possible to control the wharf borer beetles with a wood preservative that has a proven effect against rot and fungus, but also unwanted insects. Sometimes the woodwork may have taken so much damage from the visit of the wharf borer beetles that it may be necessary to replace the wood. Here it can be an advantage to use pressure impregnated wood. Action should also be taken to reduce the humidity in the room so that the wood is less vulnerable to new attacks. This can be done by repairing leaks, by improving ventilation in the room or by increasing drainage.
"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)