May 29, 2020
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Invasive trifecta, May 18-22: Emerald Ash Borer Awareness Week, Arbor Week and National Invasive Species Awareness Week

Community Author: Maine Department of Agriculture, Conservation and Forestry
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AUGUSTA — May 18-22, the Maine Department of Agriculture, Conservation and Forestry (DACF) is marking Emerald Ash Borer Awareness Week, Arbor Week and with states across the nation, National Invasive Species Awareness Week (NISAW).



DACF’s Forest Health & Monitoring and Animal and Plant Health divisions are asking everyone to take time out for trees and, in particular, look at ash trees for signs of the destructive emerald ash borer (EAB). Since discovering EAB in northern Aroostook County in May of 2018 and western York County, during September 2018, DACF established a quarantine to protect Maine’s forest and timber resources. With a Cumberland County discovery (Payson Park, in Portland Sep 2019), Maine’s EAB quarantine also includes Cumberland County and four southwestern towns in Oxford County. 


Early detection of EAB in new areas helps the MFS target resources to help slow the natural and human aided spread of this devastating insect and homeowners and land managers make informed decisions about managing their ash trees. “EAB is a real threat to ash trees in Maine,” DACF Commissioner Amanda Beal said. “Our ash trees appear to have little native resistance, and the borer kills trees very quickly. We need to know if the borer is here, and we need everyone’s help.”


The brilliant green adult beetles will not be visible in Maine this time of year, but there are many signs our ash trees may show when infested. The Department site is an excellent resource to learn more about EAB and to report suspected attacks. 


EAB is native to Asia and probably hitched a ride to North America on crates, pallets, or other solid-wood packing material in the late 1990s. Movement of infested firewood has been a critical part of its rapid spread across eastern North America. EAB can move only about a half a mile a year on its own but can move hundreds of miles in a single day within a piece of infested firewood.


Emerald ash borer is not the only threat to our forests that can move in the seemingly good firewood. Numerous other insects and diseases can also hitchhike in wood. Spread the word: use local heat treated firewood. If you have friends or family planning to visit Maine, make sure they are aware of the state and federal rules that ban the movement of untreated firewood ( Sources of treated or local firewood can be found online at firewood scout



Arbor Week happens each spring, and MFS and Project Canopy use this as a focused opportunity to encourage people to plant and care for trees. It is also the perfect opportunity for everyone to learn more about invasive insects threatening Maine’s urban landscapes and forests. In addition to educational opportunities, during Arbor Week, MFS and Project Canopy honor communities throughout Maine who have earned Tree City USA designation. These are cities and towns with strong urban- and community forestry programs and community leaders and citizens dedicated to protecting and growing their investment. Tree City USA awards set the standard high for others to follow.  



NISAW is a nationwide event designed to raise awareness of invasive species. In Maine, invasive species are more than a threat, and they are taking their toll on the economy. 

  • Invasive terrestrial plants threaten Maine’s wildlife and can harm working forests and productive farms. Plants such as glossy buckthorn steadily invade high-quality forests, crowd out native trees, shrubs, and wildflowers, and out-compete the next generation of trees. Along rivers and streams, Japanese knotweed forms dense stands that worsen flooding and prevent colonization by native plants. Knotweed roots and shoots are carried downstream in floodwaters, spreading the problem to new locations. Maine prohibits the sale of thirty-three species of invasive plants, and over 100 species are listed on an Advisory List of invasive plants to help guide land managers. The Maine Natural Areas Program (MNAP) within DACF tracks invasive plant distribution and management using the online mapping tool iMapInvasives. It encourages Mainers to work with their town conservation commission, local land trust, or garden club to spread the word about invasive plants and work together to remove them. For more information, visit the MNAP website or

  • Maine’s forest trees are under attack from multiple invasive forest insect pests, and the threat of new pests invading Maine is constant. Invasive insects such as EAB and hemlock woolly adelgid (HWA) will forever change Maine’s forests as they spread and continue to kill trees throughout the state. Other invasive pests like browntail moth directly affect human health by causing severe skin rashes and respiratory reactions. Other nearby invasive insects like Asian longhorned beetle or diseases like oak wilt have similar potential to destroy Maine’s forests even more so in the future if they hitchhike within infested firewood. MFS has a strict out-of-state firewood ban to prevent devastating introductions like these. Natural resource managers everywhere continue to encourage the use of local firewood At DACF, the divisions of Forest Health & Monitoring and Animal and Plant Health, working together as Maine Bug Watch, monitor and control invasive insects and diseases whenever possible.

  • (Courtesy MIFW) The illegal stocking of species like northern pike, black crappie, or largemouth bass can have the most significant and apparent impacts on Maine’s native fisheries. Still, sometimes the release of new fish species can occur for other reasons. These illegal acts are often intentional, for instance, when someone wants a particular species of sport fish in a lake close to their home. Unintentional introductions can happen as a result of negligence related to threats found in an angler’s bait bucket. While the level of risk from this type of introduction may be less than that from the intentional establishment of large predatory species, impacts to native fish populations can occur. MDIFW already limits the fish species that can legally be used as bait and prohibits the unauthorized importation of baitfish from outside the state as two strategies to reduce risk. Still, recently a third strategy was employed to increase awareness related to using live fish as bait. In January 2020, MDIFW changed fishing regulations in northern Maine to prohibit the use of live fish as bait under the general law and only allow fishing with live bait fish on certain waters (listed explicitly in Maine’s Open Water and Ice Fishing Laws). This change reinforces the importance of this region’s abundant native and wild fishery resources. It stresses the potential damage to those fisheries with the introduction of baitfish where they don’t belong.
  • Maine’s pristine lakes are also threatened by invasive aquatic plants. The infestation of Maine’s lakes and ponds by aggressive non-indigenous plants has the potential to interfere with recreation, alter fish and wildlife habitat, degrade water quality and overshadow virtually all other lake water quality issues and concerns. This form of “biological pollution” is self-sustaining. One inadvertently transplanted plant fragment or seed from a boat trailer is all that it takes to begin this environmental nightmare. Maine is the final frontier to be conquered by many of these “aquatic invaders.” All of our neighboring states are embroiled in costly and frustrating battles to control invasive aquatic species (IAS). Learn more and report suspicious plants to the Maine DEP Invasive Aquatic Plant Program.