The Viridian Villain

EAB damage visible in a mulched ash tree
EAB trap placed by Oregon Department of Agriculture with many trapped insects
Insect trap placed by Oregon Department of Agriculture in Forest Grove, Oregon

Kelly’s Field Notes

Common Name: Emerald ash borer

Family: Buprestidae

Genus and Species: Agrilus planipennis


Emerald ash borers are beautiful insects! They are vibrant jewel colored (emerald) green. They are 8.0-14mm (0.31-0.55 in) in length. Larvae are long and white, about 38 mm (1.5 in).

The Emerald ash borer is native to East Asia, but has since spread to Eastern Ukraine, Russia, Canada, and the United States. They were first discovered in Detroit, Michigan and in Windsor Ontario in the summer of 2002. They likely have been here as long as the 1990’s and came through shipping pallets from China. Once they reached Michigan they spread through shipping firewood, wooden pallets, and nursery trees. Never cross state lines with firewood!

Life Cycle:

Emerald ash borers begin life as eggs laid in crevices of host tree bark (60-100 eggs in one female’s lifetime!). Eggs are laid in late June/early July in North America. Once they hatch, in 7-10 days, like offspring everywhere, they are very hungry! They feed on the tissue of the tree just underneath the bark all summer. Their feeding pattern runs in an S-shape, which makes it difficult for the tree to get nutrients from its roots up to its leaves. This feeding pattern eventually kills the tree. They then form a pupa and overwinter until the Spring. Adults emerge in the Spring and feed on the leaves. Depending on the time of year when the eggs are oviposited (laid) and the health of the tree this entire process can take one to two years.

In China the emerald ash borer feeds on ash trees that are stressed, declining, or dying.


Invasive species are such an issue within their new ranges because the species around them (plant and animal) did not have the advantage of evolving alongside the indaer. This leaves the native species without defenses against the invader. Sometimes this shows itself in predators not interested in eating the invader, the invader bringing new diseases to the new range, or in this case trees without the ability to defend themselves against the emerald ash borer. Luckily for us, woodpeckers do eat the emerald ash borer’s larvae! In fact, if you see an ash tree with an unusual amount of woodpecker holes it could be an indicator that the tree has an infestation. Other indicators are D-shaped holes from where the adults are exiting the tree, yellowing foliage, crown defoliation, vertical cracks running up the tree, and shoots growing out of the lower part of the tree near the roots.

In 2007, three Chinese species of parasitoid wasp were released in several states to try to manage the emerald ash borer numbers. In 2020, the USDA reared 550,000 parasitoid wasps (four species) and released them in over 240 sites. The battle continues but things are looking up!


The United States Department of Agriculture calls the emerald ash borer “the most destructive invasive forest insect ever to have invaded North America.”

In the U.S. it can currently be found in 36 states and the District of Columbia; Alabama, Arkansas, Colorado, Connecticut, Delaware, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Nebraska, New Hampshire, New Jersey, New York, North Carolina, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Vermont, Virginia, West Virginia, and Wisconsin.

As of the writing of these notes, its detection in Oregon is very new! It was discovered on June 30th in Forest Grove, the first sighting on the West Coast.

In Canada it can currently be found in 5 provinces; Ontario, Quebec, Manitoba, New Brunswick and Nova Scotia.

In rare cases they have been found on other trees (white fringetree, olive tree), but mostly stick to ash trees. In North America we have twenty species of Ash. Research indicates the Blue ash (Fraxinus quadrangulata) is mostly resistant though it does sometimes succumb.

Super Powers:

  • Big Appetite - Destroyer of Ash Trees! Ash trees are used to create furniture and baseball bats and are frequently used as street trees in cities.

  • Super Flight - Females can fly up to 12 miles a day for six weeks after mating.

  • Structural coloration - their metallic colors don’t come from pigmentation but instead come from ridges on their bodies that act like an array of lenses canceling some colors and amplifying others, kind of like the rainbow colors of a DVD. We’re not really sure what the function of this is, but it could be to attract mates or to mimic the lens properties of raindrops on leaves, working as camouflage.

  • Stealth - they can go undetected for several years, then it’s too late to save your trees!

Emerald Ash Borers in Culture:

  • They have killed billions of ash trees across the U.S. and Canada since 2002.

Book Recommendations:

Evans, Arthur V. "Beetles of Eastern North America." Beetles of Eastern North America. Princeton University Press, 2014.

Where To Report a Sighting:

USDA’s Website -

Please check this website for who to contact if you’ve seen an emerald ash borer in your state:

Websites of Interest:

Insect-obsessed artist covers Belgian palace ceiling:

Beetle Wing Art:

Victoria and Albert Museum Beetle Wing Dress:

Questions and Answers: Biological Control for Emerald Ash Borer:

Invasive emerald ash borer could wipe out native Oregon tree species:

The Emerald Ash Borer Story Map, by USDA APHIS:

“Emerald Ash Borer.” USDA APHIS | Emerald Ash Borer,


Baranchikov, Yuri, et al. "Occurrence of the emerald ash borer, Agrilus planipennis in Russia and its potential impact on European forestry." EPPO bulletin 38.2 (2008): 233-238.

Evans, Arthur V. "Beetles of Eastern North America." Beetles of Eastern North America. Princeton University Press, 2014.

Bauer, Leah S., et al. "Emerald ash borer life cycle." In: Mastro, Victor; Reardon, Richard, comps. Proceedings of the emerald ash borer research and technology development meeting; 2003 September 30-October 1; Port Huron, MI. FHTET 2004-02. Morgantown, WV: US Forest Service, Forest Health Technology Enterprise Team: 8.. 2004.

Cappaert, David, et al. "Emerald ash borer in North America: a research and regulatory challenge." American Entomologist. 51 (3): 152-165. 51.3 (2005).

Duan, Jian J., et al. "Establishment and abundance of Tetrastichus planipennisi (Hymenoptera: Eulophidae) in Michigan: potential for success in classical biocontrol of the invasive emerald ash borer (Coleoptera: Buprestidae)." Journal of Economic Entomology 106.3 (2013): 1145-1154.

“Emerald Ash Borer.” USDA APHIS | Emerald Ash Borer,

Grayson, Kristine. “The Invasive Emerald Ash Borer Has Destroyed Millions of Trees – Scientists Aim to Control It with Tiny Parasitic Wasps.” The Conversation, 18 May 2022,

Haack, Robert A., et al. "The emerald ash borer: a new exotic pest in North America." (2002).

Herms, Daniel A., and Deborah G. McCullough. "Emerald ash borer invasion of North America: history, biology, ecology, impacts, and management." Annual review of entomology 59.1 (2014): 13-30.

Quinn, Nicole F., et al. "Spread and phenology of Spathius galinae and Tetrastichus planipennisi, recently introduced for biocontrol of emerald ash borer (Coleoptera: Buprestidae) in the northeastern United States." Biological Control 165 (2022): 104794.

Siegert, Nathan W., et al. "Dendrochronological reconstruction of the epicentre and early spread of emerald ash borer in North America." Diversity and distributions 20.7 (2014): 847-858.

“Survey and Treatment Projects.” State of Oregon: Survey and Treatment Projects - Emerald Ash Borer,

Valenta, V., et al. "A new forest pest in Europe: a review of Emerald ash borer (Agrilus planipennis) invasion." Journal of Applied Entomology 141.7 (2017): 507-526.

Volkovitsh, Mark G., Andrzej O. Bieńkowski, and Marina J. Orlova-Bienkowskaja. "Emerald ash borer approaches the borders of the European union and Kazakhstan and is confirmed to infest European ash." Forests 12.6 (2021): 691.