Asian wood boring beetles threaten hardwood trees
Two Asian wood boring beetle species, Anoplophora glabripennis and Anoplophora chinensis, threaten to spread from Asia to Europe.
Both species are extremely harmful pests of hardwood trees. Their larvae live inside the tree and make large tunnels and holes in the tree trunk. Both wood boring beetle species are classified in plant health legislation as quarantine pests and any findings of them must be immediately reported to Finnish Food Safety Authority Evira.
Dissemination pathways include wooden packaging material and deciduous tree plants
Anoplophora spread via wooden packaging material and deciduous tree plants. Anoplophora glabripennis has been found in EU countries in wooden packaging materials originating from China, and Anoplophora chinensis in maple tree plants imported from China. The beetles have in some EU countries, for example Italy and Holland, been found in nature, which has lead to extensive elimination measures undertaken by the authorities.
All companies handling wooden packaging material of foreign origin are advised to monitor such material for wood boring beetles. Nurseries and plant dealers should check foreign hardwood tree plants.
Two Anoplophora glabripennis beetles found in Finland
Anoplophora glabripennis has been detected in Finland on two occasions. A dead beetle was found in 2007 in a batch of stones imported from China and a live beetle in 2010 in a delivery of garden tiles, also from China. So far there have been no findings of Anoplophora chinensis in Finland.
Evira has investigated both sites where the wood boring beetle was found. No more beetles were detected and trees in the area showed no signs of the pest. The forests near the sites of the finding will be monitored in the upcoming years for occurrence of the wood boring beetle.
Characteristics: large size, spots and long antennae
The wood boring beetle species discussed above are almost identical in appearance. They are large, about 2.5-3.5 cm in length and about 1 cm in width. They are black with white irregular spots. Their antennae are longer than their body and a special feature of these horns is that they are striped. The stripes can be black, white or light blue. The beetle's legs are bluish in colour.
Infested trees show round holes
The larvae of the A. glabripennis beetle can infest the whole length of the tree trunk and also the branches. The larvae of the A. chinensis beetle, on the other hand, chew tunnels in the bottom part of the trunk and in the roots. The tunnels of larvae are right under the bark or in the wood. Adult beetles make large and round exit holes, about 10-13 mm in diameter. Sawdust on the trunk or at the base of the tree is a giveaway sign of wood boring beetles. Wounds on the bark, discolouration of the bark or wilting of the tree plant can be indications of beetle larvae inside the trunk.
The telltale signs of the large poplar longhorned beetle ( Saperda carcharias), which occurs naturally in Finland, are very much like those caused by the Anoplophora beetles; the larvae chew similar tunnels and the adult beetles make same kind of exit holes in the trunk.
Chewing marks and sawdust reveal infested wooden packaging material
The presence of wood boring beetles in hardwood packaging material is indicated by large holes, which are 10-13 mm in diameter, as well as by larvae tunnels and sawdust.
Many domestic deciduous trees act as host trees
Wood boring beetles use a wide variety of host trees. Finnish hardwood trees that can become infested include e.g. maple, birch, aspen, poplar, bird cherry, goat willow, alder, cherry tree, horse chestnut, and apple, plum and pear trees. Most findings of wood boring beetles in Europe have been in maple trees.