Park gains data from purple bug traps

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Date: June 23, 2008

Why can’t campers bring their own firewood into the park?  And what are those bright purple “lanterns” hanging in trees near the park’s campgrounds and picnic area?  The answer to these questions is actually interrelated; it all has to do with the emerald ash borer and its ability to spread and kill trees.

“Forest pests are becoming an ever greater concern,” said Superintendent Patrick Reed.  “Insects and fungi are spreading arboreal diseases with devastating results.  We’re trying to determine what is presently in the park and how to combat it.”

“These strange looking traps have been strategically placed around the park to detect the arrival of a new, non-native insect pest, the emerald ash borer,” said Brice Leech, the park’s resource management specialist.  “So far, the emerald ash borer has not been found at Mammoth Cave.  Preventing new pest introductions is our best means to protect the native forests.”

U.S. Department of Agriculture research indicates the beetles are attracted to the color purple and a lure that smells like a stressed ash tree. The trap exterior is coated with a sticky material which captures insects for periodic removal by park staff.

The Asian emerald ash borer was first discovered in the U.S. in Southeastern Michigan in 2002, and millions of ash trees have been killed there in only a few years. The 1/2 inch-long green beetle lays eggs in bark crevices on all species of ash. Upon hatching, larvae burrow under the bark, creating feeding tunnels that interfere with the tree’s ability to translocate nutrients and fluids. The tree gradually starves and dies.  The pest has since spread from Michigan to three adjoining states, as well as to parts of Maryland, Pennsylvania and West Virginia. 

“Our biggest concern is that the emerald ash borer may be transported via firewood and nursery stock from quarantined areas of the country into new locations, like the park,” added Leech.  “We want to protect ash trees since they are an important part of the whole park ecosystem.”

Federal regulations prohibit transportation of any firewood from four quarantined states: Michigan, Ohio, and Indiana and Illinois which now host the emerald ash borer.

Park officials say that the trapping program at Mammoth Cave is part of a much broader effort being coordinated by the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS).  Under APHIS guidance, traps have been placed in a100-mile-wide band outside the known infested area.  Mammoth Cave NP is outside that 100 mile radius, but is part of a network of selected areas that may be at high risk for new infestation because they attract a sizable number of visitors who reside in infested counties. More information is available at:



Last updated: April 14, 2015

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