The emerald ash borer (EAB), Agrilus planipennis, is an eastern Asian beetle that belongs to the metallic wood-borer family (Buprestidae). EAB was discovered in southeastern Michigan near Detroit in the summer of 2002. It has since become established in Michigan, Ohio, Indiana, Virginia, Pennsylvania, Maryland, New York and Ontario.  In the central United States, it has killed green, white, and black ashes in forested and landscaped settings and is spreading towards Connecticut.  This species poses a significant threat to ash trees, which are an important component of many Connecticut forests (a recent study estimated that Connecticut forests have nearly 25 million ash trees).  Ash trees in Connecticut may be predisposed to attack because many already are stressed by infections of one or more plant pathogens.  Ashes are valued highly for shade trees, furniture, baseball bats and firewood.  With interstate movement of wood and nursery stock and with international shipment of solid-wood packing material, it is critical to monitor this situation so as to protect forests and ornamental shade trees in Connecticut.

What to Know About Emerald Ash Borer

• It attacks only ash trees (Fraxinus spp.).
• Adults are dark metallic green, a half-inch long and one-sixteenth of an inch wide.
• Larvae are flat, legless, heavily fragmented, creamy white, and reach one inch in length when fully mature
• Adults leave a D-shaped exit hole in the bark when they emerge in spring.
• Woodpeckers like EAB larvae; heavy woodpecker damage on ash trees may be a sign of infestation.
• It probably came from Asia in wood packing materials
• Regulatory agencies and the USDA have started enforcing quarantines and fines to prevent potentially infested ash trees, logs or hardwood firewood from moving out of areas where EAB occurs.
• There are several different insecticide options that can be administered for controlling EAB depending on the health of the tree (trunk injections, soil injections, lower trunk sprays and cover sprays)
• There is still ongoing reseafch on how to best control EAB

How do I tell if my ash tree has been infested by emerald ash borer?

Common signs of infestation include D-shaped exit holes through the bark about one-eighth of an inch wide, S-shaped larval galleries just beneath the bark, thinning canopy, vertical splits in the bark, and unusual shoots sprouting from the main trunk or base of the tree.

What is the lifecycle of emerald ash borer?

Emerald ash borer produces only one generation per year. Adults emerge from late May through early August, with emergence peaking in early July. They feed on foliage for one to two weeks prior to mating. Females produce about 50 to 100 eggs, which are laid individually on the bark surface or within bark cracks and crevices. As larvae hatch, they tunnel into the tree, where they feed on the phloem and outer sapwood. Larvae continue to feed through summer and into the fall, with most completing their development prior to over-wintering in the outer bark or just under the inner bark within the outer inch of sapwood. Pupation occurs in mid- to late-spring. Adults emerge soon thereafter to complete the cycle.

How does emerald ash borer spread?

After emergence from their host tree, emerald ash borer adults fly (in general as far as one-half mile) to nearby ashes to mate and lay eggs. In addition, humans can contribute to the rapid spread of this beetle. The Ohio and Maryland infestations have been traced to infested nursery stock imported from Michigan before the insect was discovered. Transport of firewood and other ash materials from infested areas is another way it is spread.

What damage does emerald ash borer cause?

Emerald ash borer larvae tunnel under the bark of the host tree, feeding on the phloem tissue. The damage caused by the larvae disrupts the flow of nutrients between the tree’s roots and canopy. This damage results in canopy thinning, branch dieback, and eventually tree death. Larvae can destroy ashes within two to four years, but a heavy infestation could kill a tree in as little as one year.

In order to prevent or lessen the spread of invasive pests, please do not transport firewood more than 50 miles from its source.

If you find the emerald ash borer within Connecticut. please report it to the Connecticut Department of Agriculture  or the US Department of Agriculture.

If your hemlock trees seem to be dying and/or are covered with a strange, white fuzzy substance, it’s probably due to an infestation by Hemlock Woolly Adelgid (HWA).

The Hemlock Woolly Adelgid (Adelges tsugae Annand) is a destructive fluid-feeding insect pest that feeds on eastern North American hemlocks (Tsuga canadensis and T. caroliniana). It is native to Japan, and was accidentally introduced to this continent earlier this century.

HWA first appeared in Connecticut in 1985, probably as a result of dispersal by hurricane Gloria from Long Island, where infestations had existed several years previously. HWA is dispersed by wind, birds, deer, and humans, and is moving north at a rate of about 30 kilometers per year. The most obvious sign of infestation is the presence of white woolly egg sacs on the underside of hemlock needles, especially on new growth.

Lifecycle of the Hemlock Woolly Adelgid

Hemlock woolly adelgid has two generations per year in Connecticut. All populations are made up of females that reproduce asexually. In early spring, overwintering females lay between 100 and 300 eggs in the woolly egg sacs beneath the branches. Mobile larvae, known as crawlers, emerge from the eggs in April or May to search for suitable feeding sites. Wind, birds and mammals often spread crawlers to nearby hemlocks.

Once settled at the base of hemlock needles, crawlers become immobile nymphs which feed and mature into wingless or winged adult females by early summer. The winged form will die after searching for a suitable spruce tree that is not found in North America. The wingless form lays another 100 to 300 eggs on hemlock. Crawlers emerge from these eggs to search for suitable feeding sites.

Once settled, the hemlock woolly adelgid becomes dormant until October or November, when it resumes development. Feeding continues throughout the winter and early spring by piercing at the base of the needles. Shortly after infestation, this feeding has the effect of desiccating the needles and causing them to die and fall to the ground.

Infested trees usually die within 9 years, and have been killed in as little as 4 years. In areas such as southern Connecticut which have been infested for several years, massive hemlock die-offs are occurring.

In contrast, it appears that in Japan hemlocks are protected by the presence of abundant and efficient natural enemies to HWA. Current research on HWA is focusing on the identification of a natural predator which will remain viable and effective at regulating HWA populations if introduced to the northeastern United States. The results of this research are promising. In small introductions of Pseudoscymnus tsugae, a coccinellid beetle, to infested Connecticut hemlock stands, the beetle appears to be successful at greatly reducing HWA numbers. The next test for P. tsugae will be to determine whether or not it can maintain its population and keep pace with HWA’s migrations northward at sufficient densities to regulate HWA populations.

How to Recognize Hemlock Woolly Adelgid

• White woolly egg sacs on the underside of hemlock needles
• Thinning of needles (less dense)
• Grayish-green appearance (hemlocks naturally have a shiny, dark green color)

How to Control Hemlock Woolly Adelgid

Horticultural oil (2 % or lower) or insecticidal soap sprays can be applied at anytime but preferably in spring, to suffocate HWA on accessible trees but applications are costly and impractical for large scale control. Coverage needs to be thorough to be effective and needs to be repeated annually to prevent reintroductions from taking hold. These least toxic options are preferable to other pesticides as there are minimal impacts on beneficial or non-target organisms. Chemical control is also limited in its use in the forest setting, although newer chemicals such as imidacloprid (Bayer Corporation) are increasingly used for systemic treatments by arborists to control HWA. Soil drench imidacloprid applications are now available for homeowner use.

However, the chief hope for long term HWA management remains biological control using introduced specialist predators from Japan , China and British Columbia, Canada. The only mass-reared predator from Japan currently available for implementation in infested eastern states is Pseudoscymnus tsugae (Coleoptera:Coccinellidae), a tiny black ladybeetle, about 2mm in length, of the Tribe Scymnini from Japan. Over eight years of careful research at the Connecticut Agricultural Experiment Station, largely supported by the USDA Forest Service, has documented its life history, biology and potential as a biological control agent, including experimental field releases and short-term impact on HWA in Connecticut and Virginia. Field release sites are still being monitored and assessed three to five years after release. The predator is considered established in Connecticut where overwintering adults have been recorded yearly since its first release in 1995 and reproduction has been documented in the field. To date, nearly a million P. tsugae have been released in over 100 sites in 15 eastern states from Georgia to Maine and this species has also been recovered from release sites in other states. Other related ladybeetle predators from China (various Scymnus species), and a derodontid beetle, Laricobius nigrinus , from British Columbia, are under investigation as additional biological control agents at the USDA Forest Service, Hamden, Connecticut, and at Virginia Polytechnic and State University, respectively. Yet another avenue being explored is that of entomopathogenic fungi for biological control of HWA at the University of Vermont.