Forest Pest Insects in North America: a Photographic Guide

Emerald ash borer

Agrilus planipennis Fairmaire (Coleoptera: Buprestidae)

Orientation to pest

Emerald ash borer, Agrilus planipennis Fairmaire, is an invasive borer from northeast Asia threatening North American ash trees (Fraxinus). It was first detected near Detroit, Michigan and likely was introduced in the 1990s. It is now found in 14 other states and two Canadian provinces, and the infested range is expanding rapidly. Emerald ash borer attacks and kills healthy ash trees from ones several inches in diameter to mature trees. Massive mortality to ash of several species has occurred since the species' invasion in both landscape plantings and natural ash-dominated communities, especially in riparian areas. Larvae feed on phloem and make serpentine galleries that girdle and kill trees when the larval densities are high. Mature larvae tunnel into sap wood to pupate. In northern areas (e.g., Michigan), a single generation may require two years, but in mid-Atlantic states (e.g., Maryland), a generation can be completed each year. In dense populations, woodpeckers consume many larvae.

Hosts commonly attacked

Most North American Fraxinus species are susceptible, but so far the most affected species have been white (Fraxinus americana L.), green (Fraxinus pennsylvanica Marshall), and black (Fraxinus nigra Marshall) ash.

Distribution

The North America infested area is centered on Michigan. Extensive infestations exist in Ontario, Illinois, Indiana, Ohio, Kentucky, Pennsylvania, and Maryland, and smaller infested areas are found in Quebec, Minnesota, Iowa, Wisconsin, Missouri, Tennessee, New York, Virginia, and West Virginia (as of 2010).

Distribution in 2010 of emerald ash borer Cornell University, Cooperative Extension • The New York Invasive Species Clearinghouse 1613x1238
Figure 1. Distribution of emerald ash borer in 2010

Images of emerald ash borer

Adults of emerald ash borer Howard Russell, Michigan State University, Bugwood.org 768x512 / 1536x1024
Adults of emerald ash borer David Cappaert, Michigan State University, Bugwood.org 768x512 / 1536x1024
Adults of emerald ash borer David Cappaert, Michigan State University, Bugwood.org 768x512 / 1536x1024
Larval galleries of emerald ash borer. Troy Kimoto, Canadian Food Inspection Agency, Bugwood.org 768x512 / 1536x1024

Larval galleries of emerald ash borer. Michigan Department of Agriculture, Bugwood.org 768x512 / 1536x1024

Larval galleries of emerald ash borer. Edward Czerwinski, Ontario Ministry of Natural Resources, Bugwood.org 768x512 / 1536x1024
Figure 2. Adults of emerald ash borer, Agrilus planipennis
Emerald ash borer eggs are white when freshly laid Houping Liu, Michigan State University, Bugwood.org 768x512 / 1536x1024
Emerald ash borer eggs turn tan as they age Houping Liu, Michigan State University, Bugwood.org 768x512 / 1536x1024
Figure 3. Emerald ash borer eggs are white (left) when freshly laid, but turn tan as they age (right)
Feeding stage larvae of emerald ash borer: full grown 4th instar David Cappaert, Michigan State University, Bugwood.org 768x512 / 1536x1024
Feeding stage larvae of emerald ash borer: second, third and 4th instar David Cappaert, Michigan State University, Bugwood.org 768x512 / 1536x1024
Figure 4. Feeding stage larvae of emerald ash borer: left - full grown 4th instar; right - second, third and 4th instars Figure 5. Larval galleries of emerald ash borer.
Prepupae in chambers formed in sap wood by mature larvae Brian Sullivan, USDA APHIS PPQ, Bugwood.org 768x512 / 1536x1024
Prepupa of emerald ash borer in chamber in sap wood David Cappaert, Michigan State University, Bugwood.org 768x512 / 1536x1024
D-shaped emergence hole of emerald ash borer (left) and hole made by woodpecker (right) where an emerald ash borer larva was removed David Cappaert, Michigan State University, Bugwood.org 768x512 / 1536x1024
Dying or dead landscape trees affected by emerald ash borer Steven Katovich, USDA Forest Service, Bugwood.org 768x512 / 1536x1024

Dying or dead landscape trees affected by emerald ash borer David Cappaert, Michigan State University, Bugwood.org 768x512 / 1536x1024
Figure 6. Prepupae in chambers formed in sap wood by mature larvae Figure 7. Prepupa of emerald ash borer in chamber in sap wood Figure 8. "D"-shaped emergence hole of emerald ash borer (left) and hole made by woodpecker (right) where an emerald ash borer larva was removed
Suckering is a sign of infestation Joseph O'Brien, USDA Forest Service, Bugwood.org 768x512 / 1536x1024
Bark splits are a sign of infestation Michigan Department of Agriculture, Bugwood.org 768x512
Dead and dying ash in forest area due to emerald ash borer Troy Kimoto, Canadian Food Inspection Agency, Bugwood.org 768x512 / 1536x1024
Figure 9. Signs of infestation: left, suckering: right, bark splits Figure 10. Dead and dying ash in forest area due to emerald ash borer Figure 11. Dying or dead landscape trees affected by emerald ash borer
Tree removal was tried, unsuccessfully, as a means to eradicate emerald ash borer populations. David Cappaert, Michigan State University, Bugwood.org 768x512 / 1536x1024
Tree removal was tried, unsuccessfully, as a means to eradicate emerald ash borer populations. Daniel Herms, The Ohio State University, Bugwood.org 768x512 / 1536x1024
Girdling trees can be an effective survey method to detect emerald ash borers Pennsylvania Department of Conservation and Natural Resources - Forestry Archive, Bugwood.org 768x512 / 1536x1024
Larva of the native North American parasitoid David Cappaert, Michigan State University, Bugwood.org 768x512 / 1536x1024
Pupa (in cocoon) of the native North American parasitoid David Cappaert, Michigan State University, Bugwood.org 768x512 / 1536x1024
Adult of the native North American parasitoid Jian Duan, Bugwood.org 768x512 / 1536x1024
Figure 12. Tree removal was tried, unsuccessfully, as a means to eradicate emerald ash borer populations. Figure 13. Girdling trees can be an effective survey method to detect emerald ash borers
Chinese parasitoid of emerald ash borer eggs Debbie Miller, USDA Forest Service, Bugwood.org 768x512 / 1536x1024
Chinese larval parasitoid Houping Liu, Michigan State University, Bugwood.org 768x512 / 1536x1024
Chinese emerald ash borer larval parasitoid Jennifer Ayer, Bugwood.org 768x512
Figure 14. The Chinese parasitoid of emerald ash borer eggs, Oobius agrili Figure 15. The Chinese larval parasitoid Tetrastichus planipennisi Figure 16. The Chinese emerald ash borer larval parasitoid, Spathius agrili Figure 17. Larva, pupa (in cocoon), and adult of the native North American parasitoid Atanycolus cappaerti Marsh and Strazanac

Important biological control agents related to this pest species

Natural enemies of emerald ash borer that have been collected in the native range (especially in China and Russia) include two larval parasitoids (the eulophid Tetrastichus planipennisi Yang and the braconid Spathius agrili Yang), and an egg parasitoid, Oobius agrili Zhang and Huang (Hymenoptera: Encyrtidae). Additional parasitoids have been identified and are under consideration for importation, including Spathius n. sp. and Antanycolus picipes Telenga from Russia. One group of native North American parasitoids, braconids in the genus Atanycolus, has adopted emerald ash borer and causes up to 20-40% mortality of the larvae in some areas.

Web links for information on emerald ash borer

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