European Spruce Bark Beetle Fact File
The European spruce bark beetle is known from Europe and Asia.
They are best known for the patterns which are created in trees as they reproduce. Females deposit their eggs in a chamber bored in a tree trunk and the young then burrow out creating patterns as they go.
These tiny beetles measure in at just 4-5.5mm (0.16-0.22in) long. Often they are found from their burrowing in a tree trunk.
Read on to learn more about these incredible invertebrates.
Their body is covered black or dark brown across its body. Around the front, head and sides of the body they are covered by long, yellow hairs.
European spruce bark beetles are insects and as such have the typical six legs and a body divided in to three segments, the head, thorax and abdomen.
Their abdomen features some small spines as with all species in their genus.
The European spruce bark beetle is a small insect measuring in at just 4-5.5mm (0.16-0.22in) long.
The European spruce bark beetle is a herbivore which feeds on the bark in which the adults, larvae and pupae spend their time burrowing. They feed on the phloem.
Suitable hosts on which they can feed include spruce, fur, larch and pine.
European spruce bark beetles are found in parts of Europe and Asia. Outbreaks have been occurring in the United Kingdom where the species is not naturally found.
The threat of introduction to other areas is seen as likely as a result of unprocessed wood products being transported with this species inside. In the period from 1985 to 2000 they were intercepted over 200 times at US ports of entry.
These animals primarily live inside the bark of spruce trees.
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A male beetle will dig a nuptial chamber in to the bark of a tree. He then emits pheromones which will attract the interest of females. As many as four may come join him and then bore an egg gallery off his chamber.
In their egg chamber they deposit up to 50 eggs. Egg laying occurs over a period of three weeks. The first eggs laid become half grown larvae before the last egg is laid.
After hatching the larvae will feed on the bark in their chambers. Larvae lack legs and have a white colored body with brown mandibles. These then pupate in to adults who feed briefly before burrowing out and emerging in to the wider world.
These young individuals will swarm to a new host tree. If conditions are cold they will overwinter under the bark or among leaf litter.
In their natural range the emergence will occur during spring.
Throughout much of their range they have the ability to raise two broods each year.
These beetles are a damaging pest of a range of trees including spruce, pine, fur and larch. Seemingly healthy trees may be killed during large outbreaks. They also carry fungi between trees which can further contribute to their decline.
Predators and Threats
Natural predators of the species include woodpeckers and larger insects.
These beetles have been able to expand their range through introduction to new areas as a result of the movement of freight.
They are also known as the eight-toothed spruce bark beetle.
Beetles such as the European spruce bark beetle which are part of the genus Isp are referred to as engraver beetles due their system of burrowing in to trees.
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Gilles San Martin from Namur, Belgium, CC BY-SA 2.0 <https://creativecommons.org/licenses/by-sa/2.0>, via Wikimedia Commons
Tõnu Pani, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons
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