Japanese sawyer beetle
The Japanese sawyer beetle (Monochamus alternatus), also known as Japanese pine sawyer, is a long-horned beetle that attacks weak or dead trees.
It targets many species of pine and some species of spruce, fir, cedar, and larch.
Background
Japanese sawyer beetle is indigenous to Japan, but is also found in China, Taiwan, Korea, Laos, and Vietnam.
The beetle is most likely to arrive in imported timber and wood used for pallets and other packing materials from Asia.
Impacts
The Japanese sawyer beetle, like other Monochamus beetles, can spread the pine wilt nematode (Bursaphelenchus xylophilus). Their feeding and egg laying behaviour introduce the damaging nematode to new areas, which is of significant concern to the environment.
The Japanese sawyer beetle lays eggs into trees that are stressed due to damage or disease, or trees which have recently been killed.
Infestation of recently felled trees can reduce their value as timber. Look for:
- larval tunnels and exit holes in the wood, up to 10 millimetres wide
- sawdust-like frass falling from damaged timber.
Identification
Like other long-horned beetles, Japanese sawyer beetle is characterised by having antennae longer than its body.
Adult beetles are 15 to 30 millimetres long and 4 to 10 millimetres wide. They are a mottled orange-brown colour with defined stripes running the length of the body.
Larvae are white coloured grubs up to 43 mm in length. Eggs are about 4 mm long and curved in shape.
After emergence, the Japanese sawyer beetle feeds on foliage and completes its maturation, which takes up to a week for a male and 3 weeks for a female to lay eggs. The female gnaws a wound in the bark and lays a single egg in each wound.
While there are records of adults flying up to 3 kilometres, most adults fly less than 200 metres.
