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Citrus Longhorn Beetle
14/08/2008
The Scottish Government is encouraging gardeners to be vigilant and look out for Citrus Longhorn Beetle.
The Citrus Longhorn Beetle (Anoplophora chinensis) is an invasive non-native insect which could harm woodland areas and garden plants in the UK. It has recently been identified on Acer plants (Acer palmatum or 'Japanese Maple') imported from China via the Netherlands and distributed by mail order. This pest is not established in Great Britain but there have been several recent findings in different parts of the UK, including one in Scotland.
Although the beetle is known to have been introduced in Acers, it can affect a wide range of trees or shrubs, such as oak, beech, ash, maple, apple, pear, willow, hibiscus, horse chestnut, hornbeam, hazel, birch, mulberry and rose.
What to look out for:
Citrus Longhorn beetles develop inside plant stems and tree trunks, taking between one and three years to emerge, and are therefore difficult to detect.
Prior to emergence, there are no obvious symptoms of infestation or the presence of a larva or pupa within a plant or tree. However, large (6-11 mm) exit holes are left by the emerging adults in the stem. These exit holes may be just above ground level, but can also be just below ground level and as such cases are not visible. Other symptoms can include:
- Scraped sections of bark
- Chewed leaves and damage to the petioles by adults
- T-shaped egg slits in bark
- Saw-dust like 'droppings' or wood pulp around holes and larval tunnels in the wood under loose or thin bark. Examination of the ground at the base of the shrub or tree for signs of wood shavings provides a rapid method of detecting activity of late stage larvae.
These large black beetles grow to between 21-37mm long and have distinct white markings and long "horns" or antennae. The antennae are longer than the body and are black with white bands. It could be found on a wide range of trees or shrubs.