Latin: Ernobius mollis
The soft wood borer beetle is not a rarity in this country, and it likes to settle in dry bark-clad conifers. The soft wood boring beetle – also known by its Latin name Ernobius mollis – differs slightly from other types of borer beetles. This is due to its skin skeleton, which is not as hard as in other of its fellow species.
Appearance
The fully grown soft wood boring beetle can grow between 3 and 6 millimeters long. It is covered with fine, short hair. These hairs give it a light, almost golden-brown color. However, the soft wood boring beetle does not go through life with that hair splendor. Instead, the hairs wear out as the beetle gets older. This also means that the beetle becomes correspondingly darker brown. The head is partially hidden under its neck shield.
The larvae of the soft wood boring beetle can grow up to 8 millimeters long. They are curved and their legs are quite short. The bodies of the larvae have a yellowish-white color, while their heads are dark brown.
Biology and behavior
The soft wood boring beetle belongs to the family of borer beetles (Anobiidae) under the family soft borer beetle (Ernobiinae). Conifers are, as described, the preferred place for the soft wood boring beetle to settle. The soft wood boring beetle seeks out weakened and felled trees for its purpose. And as long as the bark is still intact and not dried out, it is an obvious destination for the borer beetle.
The female lays her eggs in cracks and crevices in the coniferous bark. When the eggs hatch, the newly hatched larvae gnaw deeper into the bast layer of the tree, which forms the area between bark and wood. In this area, the larvae can feed on the inner part of the bark, just as they can devour the outer layers of the sapwood.
If a conifer has been visited by larvae from the soft wood boring beetle, there will be visible signs. Under the bark, the larval passages will stand out clearly as approx. 1-millimeter-deep grooves, forming a large pattern in the wood. However, the grooves may be deeper than that. Just before the larva pupates, it gnaws even further into the tree. The larva digs approx. 1 centimeter down into the wood to achieve a more protected position in the tree.
Within one to two years, the soft wood boring beetle is fully developed, and it is getting ready to leave the tree. It happens through a round fly hole in the wood that has a diameter of about 1 to 2 millimeters.
The larvae pupate in the spring and the adult beetles can be seen in June and July. The adult beetles do not feed and only live for a few weeks. The female lays an average of 40 eggs after mating.
The passages left are filled with flour consisting of the excrement of the larvae. This flour is dark where the larvae have eaten off the bark. Otherwise, the flour has a yellowish color that is the same as that of sapwood.
In addition to conifers, the larvae can live in building materials where there is bark, which can cause problems.
Damage
One should not be fooled by the name. Because even though the word “soft” is included in the name of the soft wood boring beetle, it is by no means weak. In fact, it can gnaw through hard materials such as lead if it should be necessary.
But most often, the damage that the beetle causes to the wood itself is of a cosmetic nature. The problem arises if you use bark-edged wood of one kind or another directly with lead or cardboard. Because here the holes can cause water infiltration, which can ultimately result in an increased risk that the wood may be attacked by fungus or rot.
Prevention and pest control
In most cases, it is not necessary to set heaven and earth in motion to combat the soft wood boring beetle, as most attacks from the beetle will die out on their own. It happens when the bast layer in the wood has been eaten. If you want to speed up the process, you can choose to remove all bark residues yourself. If you want to avoid attack from the soft wood boring beetle, you can proactively proceed by avoiding the use of any kind of bark-edged wood.
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