Emerald Ash Borer

Pronunciation

How to pronounce Agrilus planipennis: /əˈɡraɪləs plænɪˈpɛnɪs/

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Summary

The Emerald Ash Borer (Agrilus planipennis) is an invasive beetle that has caused significant devastation to ash tree populations in North America. While it is native to Asia and typically does not harm local ash trees there, it has become a serious pest outside its native range and poses a significant ecological and economic threat.

Physical Characteristics

EAB Agrilus planipennis Fairmaire 1888 adult 7.5-14 mm (males smaller than females); larva up to 32 mm. Adult: elytra bright metallic green; pronotum golden-green; ventral surface lighter yellowish-green (with fine hairs in males, lacking in females); body narrow and elongate; head flat; eyes kidney-shaped, black; dorsal surface of abdomen metallic purplish-red, visible when wings are spread. Larva: body white to cream-colored, dorso-ventrally flattened; head brown, mostly retracted into prothorax; abdomen 10-segmented with a pair of brown pincer-like appendages on the last segment; segments 5-8 widen posteriorly, giving the abdomen a serrated appearance when viewed from above.

Identification Tips

Adult beetles are typically bright metallic green, about 7.5 to 14 mm long, with a bright red upper abdomen when viewed with the wings spread. Unique features include a small spine at the tip of the abdomen and serrate antennae that begin at the fourth antennal segment. Look for characteristic D-shaped exit holes in the bark made by emerging adults.

Habitat

Primarily infests ash trees (Fraxinus spp.) and is commonly found in forested areas with dense ash populations, particularly in urban and suburban environments where ash trees are prominent.

Distribution

Native to E. Asia (Russia, Mongolia, northern China, Japan, Korea); accidentally introduced to North America, currently established in the Great Lakes region and has spread to several other states (CO, TX, GA) and parts of eastern Europe.

Diet

Larvae primarily feed on the inner bark and cambium of ash trees (Fraxinus spp.), creating S-shaped tunnels as they develop. Adults also feed on ash leaves.

Life Cycle

Life cycle can span 1-2 years depending on the season of oviposition, health of tree, and temperature. Females lay eggs that hatch in about two weeks, with larvae developing through four instars before overwintering and pupating. Adults emerge in late spring.

Reproduction

Females typically can lay 40-70 eggs, but can lay up to 200 if they live longer. Eggs are laid in bark crevices and hatch into larvae that begin feeding on the tree.

Predators

Natural predators include woodpeckers, which feed on larvae, and the parasitoid wasp Cerceris fumipennis. Other parasitoids such as Atanycolus cappaerti have been researched for biological control.

Ecosystem Role

Emerald Ash Borer plays a significant role as an invasive species impacting the population dynamics of ash trees, resulting in extensive ecological consequences.

Economic Impact

Considered one of the most destructive forest pests in North America, with potential costs of $20–60 billion associated with urban ash tree removals and replacement due to infestations.

Cultural Significance

Ash trees have historical and commercial significance, such as the use of white ash in the production of baseball bats like the Louisville Slugger.

Collecting Methods

• Visual surveys for signs of infestation
• Use of trap trees
• Girdled trees to monitor for larvae

Preservation Methods

• Traps with color attractants
• Insecticide treatments

Evolution

Originated from temperate northeastern Asia; low genetic diversity present in North American populations suggests introduction from a single group of insects from central China.

Similar Taxa

• Agrilus subcinctus

Misconceptions

Emerald ash borer is often confused with other local beetle species, particularly other Agrilus species; proper identification is essential for management efforts.

Tags

• invasive species
• wood borer
• ash trees
• pest management