Agrilus planipennis

Emerald ash borer

Description

The adult emerald ash borer measures 7.5-15 mm in length and 3-3.5 mm in width, and possesses a narrow and elongated body shape characteristic of jewel beetles, with a metallic copper-green color. The female lays eggs individually on the bark of ash trees during May and June, and can lay between 65-90 eggs in her lifetime. Upon hatching, the larvae begin to excavate a tunnel immediately, primarily in the phloem area. As they mature, they create expanding serpentine galleries. The larval stage consists of four instars, and the duration of their development ranges from 1 to 2 years, depending on the climatic region. During the winter, the larva usually overwinters in the last instar, within an overwintering chamber under the bark or finely cut in wood. After emerging from the pupa, the beetle remains under the bark for 1-2 weeks before leaving the area through an exit hole typically shaped like the letter \"D,\" measuring 3-4 mm wide. From May to June, they disperse and can fly several kilometers. Overall, the emerald ash borer is a highly destructive invasive species that causes significant damage to ash trees across North America.

Symptom

Newly infested trees are difficult to detect on time. Symptoms of infestation typically appear when the tree has already sustained significant damage. One noticeable symptom is a change in the color of the leaves, and their premature falling. Additionally, damage to the tree can be indicated by increased trunk sprouting, as trees tend to respond to significant stress factors. It is also advisable to monitor the activity of woodpeckers or secondary insect pests, as they may be attracted to infested trees. If a tree shows such symptoms, it is important to perform a closer inspection. Galleries made by emerald ash borers have serpentine shapes that are initially very thin, gradually expanding over time. The galleries are filled with frass. If the population on the trunk is small, the galleries tend to point from top to bottom along the trunk axis. However, if the density is high, the galleries can lead in any direction. When adult beetles exit an ash tree, characteristic holes can be found on the trunk and branches. These exit holes are 3.5-4.1 mm in diameter and have a distinct D-shape. Therefore, detecting these holes on ash trees is a reliable indication of emerald ash borer infestation. Overall, prompt detection and treatment are essential in managing emerald ash borer infestations, as these insects can cause significant damage and even death to ash trees.

Tree Species: Elm, Ash, Walnut

Part of a plant- attacked: Tree trunk, Branch

Pest significance: Very harmful

Pest Category: Insects

Invasive Species: Yes

Present in EU: No