Emerald ash borer (EAB) is native to Asia. It has been found in Michigan, Illinois, Indiana, Iowa, Kentucky, Maryland, Minnesota, Missouri, New York, Ohio, Pennsylvania, Tennessee, West Virginia, Wisconsin, Ontario and Quebec. EAB probably arrived in the United States on solid wood packing material from Asia.
Pathways and modes of spread
Emerald ash borer can easily be spread through the movement of infested live ash trees, limbs, firewood, logs, and untreated ash lumber.
It is a small, brassy-green, metallic wood-boring beetle measuring 1/3 to 1/2 inches in length. Larvae have bell-shaped segments with two dark spines at the tip of the abdomen. These are urogomphi and are diagnostic for larvae in the genus Agrilus.
Females lay eggs 2 weeks after emergence. Eggs are initially light-yellow, turning to brownish-yellow before hatching. Eggs hatch in 1-2 weeks, and the tiny larvae bore through the bark and into the cambium and phloem. The creamy white larvae are 1 – 1 1/4 inches long with flat, broad, segmented bodies. Adults begin emerging in mid-June leaving 0.1 – 0.2 inches “D” shaped emergence holes. The life cycle in Michigan takes between 1-2 years depending on the climate.
Plant Response and Damage
Some irregular notching may be observed on the foliage as the newly emerged adults will feed on it. Larvae feed in the cambium creating S-shaped frass-packed tunnels. Vertical splits in the bark are created by the tree forming callus tissue in response to larval feeding. The damage by the larvae causes general yellowing and thinning of the foliage followed by crown dieback and the eventual death of the tree. Basal sprouting and the presence of woodpeckers may indicate wood-boring beetle activity. After 1 to 2 years of infestation, the bark often falls off in pieces from damaged trees, exposing the insect galleries.
Survey techniques include visual surveys, attractant-baited panel traps, and destructive sampling. Since it is possible to have no visible signs or symptoms in the first year of an infestation, visual surveys are helpful for locating older infestations. The panel traps have proven more effective for detecting early infestations since ti traps the adults as they are flying to new host trees. Traps should be placed when in early to mid june when adult emergence and flight is expected. Destructive sampling is performed in areas where a new infestation is suspected. This type of sampling is best done in late summer or early fall since larvae should be large enough to locate and identify.
Three species of biocontrol have been researched and are currently being deployed. They include Spathius agrili (Hymenoptera: Braconidae), Oobius agrili (Hymenoptera: Encyrtidae), and Tetrastichus planipennisi (Hymenoptera:Eulophidae). This is a long-term management method rather than one targeted at immediate control.
Although there are chemical controls available for use over wide areas, several products have been tested for protection of individual trees.
|INSECTICIDE FORMULATION||ACTIVE INGREDIENT||APPLICATION METHOD||TIMING|
|Professional Use Products|
|Merit (75WP, 75WSP, 2F)||Imidacloprid||Soil injection or drench||Mid-fall and/or mid- to late spring|
|Xytect (2F, 75WSP)||Imidacloprid||Soil injection or drench||Mid-fall and/or mid- to late spring|
|IMA-jet||Imidacloprid||Trunk injection, Arborjet||Early May to mid-June|
|Imicide||Imidacloprid||Trunk injection, Mauget||Early May to mid-June|
|Pointer||Imidacloprid||Trunk injection, Wedgle||Early May to mid-June|
|Inject-A-Cide B||Bidrin||Trunk injection, Mauget||Early May to mid-June|
|TREE-age||Emamectin benzoate||Trunk injection, Arborjet||Early May to mid-June|
|Safari (20 SG)||Systemic bark spray||Early May to mid-June|
|Astro||Permethrin||Preventive bark and foliage cover sprays||2 applications at 4-week intervals; first spray should occur when black locust is blooming|
|Onyx||Bifenthrin||Preventive bark and foliage cover sprays||2 applications at 4-week intervals; first spray should occur when black locust is blooming|
|Sevin SL||Carbaryl||Preventive bark and foliage cover sprays||2 applications at 4-week intervals; first spray should occur when black locust is blooming|
|Tempo||Cyfluthrin||Preventive bark and foliage cover sprays||2 applications at 4-week intervals; first spray should occur when black locust is blooming|
|Bayer Advanced Tree & Shrub Insect Control||Imidacloprid||Soil drench||Mid-fall or mid- to late spring|
Not all treatments are as effective as others and some are not recommended in certain situations. Contact your local extension service for chemical control recommendations specific to your state and particular situation. Results of some tests have also been posted on EmeraldAshBorer.info.
- The primary resource for Emerald Ash Borer Information in the United States
- Forest Service Emerald Ash Borer site
- Wisconsin resource site for Emerald Ash Borer
- Ohio Emerald Ash Borer site
- USDA Emerald Ash Borer site
- Indiana Emerald Ash Borer site
- Michigan Emerald Ash Borer site
- National Invasive Species Information Center Emerald Ash Borer site
- Minnesota Emerald Ash Borer site