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Stop That Beetle!



Adult beetle; Photo by Kenneth R. Law, USDA APHIS PPQ,

The invaders have shiny black bodies with white spots and long black and white antennae; they stow away in larval form in wood pallets, moving around the world in shipping containers; THEY EAT TREES. This may sound like the plot of a science fiction film, but these pests are very real insects called Asian longhorned beetles.  There are no known outbreaks in our region now, but container ports are likely starting points, so vigilance is key. 

The beetles lay eggs under the bark of hardwood trees; maple, horsechestnut, willow, and elm are among their favorites.  Beetle larvae (the worm-like immature beetles) hatch from the eggs and feed on the wood, chewing out large tunnels that quickly destroy a healthy tree.  When the adult beetles emerge from the tree they leave large round exit holes, slightly smaller than a dime.  An infestation of Asian longhorned beetles could devastate urban and wildland forests in our region. 

New York City, Chicago, and various smaller cities have removed thousands of trees as a result of Asian longhorned beetle invasions.  A closely related beetle called a Citrus longhorned beetle was found in a bonsai nursery in Tukwila, WA in 2001 and approximately 1,000 trees were removed in order to prevent a widespread infestation.  The insects often travel in pallets made from infested trees; pallets are supposed to be treated to kill the hitchhikers but the rules are not always followed.  The beetles can also move in nursery plants, as was the case in Tukwila.  There are not nearly enough inspectors to check all the pallets that arrive in a port, and if just a few beetles escape, an invasion could start undetected.  Because adult beetles don’t fly far, tree removal, quarantine areas, and prevention of wood transport can be effective, though extreme, treatments.  In most cases, beetle damage was first spotted by citizens who happened to recognize beetle damage and alert authorities.

SDOT Urban Forestry Staff attended a class presented by staff of the Animal and Plant Health Inspection Service (APHIS), an agency of the US Department of Agriculture.  We learned how to recognize adult beetles and inspect trees for beetle damage.   We plan to keep our eyes peeled, but observant and informed residents throughout the city are our first line of defense for avoiding an infestation.  So if you see a black and white beetle, or a round dime-sized hole in a tree, contact APHIS immediately:  .  There are some native beetles that look similar, but if you have any suspicions of longhorned beetle activity, report it!   

More information about Asian Longhorned Beetle (ALB):

Exit holes; photo by Richard Hoebeke, Cornell University,


Beetle in larval stage; photo by Thomas B. Denholm, New Jersey Department of Agriculture,