European Spruce Bark Beetle
FACTS, IDENTIFICATION & CONTROL
Adult European spruce bark beetles have dark brown cylindrical bodies. They range from 4 to 5 mm in length and have four spines on each side of their body. The larvae are white, legless and can grow up to 5 mm in length. The larva of European spruce bark beetles are also known as grubs. They have C-shaped bodies with amber-colored heads.
BEHAVIOR, DIET & HABITS
The European spruce beetle is native to Europe and some parts of Asia. It is considered to be Europe’s most destructive bark beetle, especially when beetle populations are high. It has been detected in North America but is usually intercepted at U.S ports of entry. The insect lives underneath the bark for most of its life cycle so it is hard to detect in early stages of development. The European spruce beetle has many plant hosts including a variety of species of spruce, fir, larch and pine.
Adult beetles begin to disperse in the spring when temperatures rise. From its host tree, the male beetle creates a chamber in which he mates with females. Because the males produce pheromones, they attract more beetles to the tree. After the female and male mate, the female excavates egg galleries under the bark and lays eggs in them. The beetles go through two generations yearly and overwinter as adults under the bark.
SIGNS OF A EUROPEAN SPRUCE BARK BEETLE INFESTATION
Common signs of a European spruce bark beetle infestation include the foliage fading from green to yellow to reddish-brown in color, dust on the surface of bark or logs, egg galleries and any round exit holes on the bark. Additionally, resin tubes may be found on tree bark. Within a few weeks of an attack, the host trees begin to die.
Preventative measures can be taken to manage the European spruce beetle, including the debarking of windthrown material to limit population growth. An integrated pest management approach can help to solve the problem by removing infested trees or using pheromone baited traps to suppress the population and outbreak. Some chemical attractants also have been used to trap the beetles or reduce their attacks.