The Maryland Departments of Agriculture and Natural Resources are cutting down hundreds of ash trees (genus Fraxinus) in parks and forests this week in Prince George’s County, as a strategy to stop an outbreak of the invasive beetle, emerald ash borer (Agrilus planipennis, Fairmaire). Since being discovered in the US, in 2003, possibly arriving in solid wood packing material from Asia, the larval life stage of the emerald ash borer has caused the destruction of 20 million ash trees across Michigan, Ohio and Indiana. Maryland potentially faces the loss of millions of trees as the distribution of the beetle leaps to the Eastern Seaboard for the first time.


Click here for the North American spread of this species (©Michigan State University Extension), and click here to view a map of the worldwide distribution of this species.

The continued spread of the emerald ash borer, and other invasive introduced forest pests and pathogens, poses a serious threat to the ecological and economic values of forest resources. It has been suggested by The Nature Conservancy that failure to stop the spread of the emerald ash borer will likely result in the elimination of the 16 ash species found in North America. This could also have detrimental knock-on effects to species such as deer, moose, beaver, rabbits and porcupines, which use ash forests for shelter, while the seeds of ash are an important food source for ducks, song and game birds, small mammals and insects. Overall, the loss of ash species within Maryland and the surrounding states may cause more than $85 billion (£43 billion) in economic damage (especially to the forest products and gardening sectors), as this insect threatens to kill up to 90 million trees in both rural and urban settings.

Research into an effective bio-control agent to eradicate the emerald ash borer invasion is still under development. However, further information is available on potentially effective insecticides from Michigan State University while further information on the species can be obtained at

To view the full list of distribution maps of plant pests and pathogen species published by CABI go to and and

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