Any appearance of the Asian Longhorned Beetle (ALB) is bad news, but this summer, the trunk-ravaging bug showed up in a particularly threatening location: across the street from Boston's beloved Arnold Arboretum. The oldest arboretum in the U.S. is home to 15,000 plants, of which more than a dozen species are favorites of the ALB. The beetle was found in six trees outside Faulkner Hospital, just yards away.

Maybe the first invasive insect to have its own Facebook page, the beetle first appeared in the U.S. at a Brooklyn warehouse nearly 15 years ago. Larvae were said to have unintentionally stowed away by burrowing themselves in wooden shipping pallets from their home in China. Several months later, a tree-pruning company unwittingly transported the insect to Long Island. Over the next decade and a half the beetle would infest trees in Manhattan, Queens, New Jersey, Ontario, Nova Scotia, and beyond, and show up in warehouses in a dozen states and Europe.

In Worcester, Mass., more than 25,000 trees were sent to the chipper two years ago after a keen-eyed resident spied the beetles in her yard. After this infestation was detected, officials around New England and the country took note. The Faulkner beetles were spotted because the Arboretum had begun a regular inspection program.

When authorities discover a tree with ALB , they act quickly, chopping it down to the root and chipping it to kill both adult and larval beetles. They then "quarantine" the surrounding area, preventing anyone from carrying infested wood or wood products in or out. It is no small task to muster this response. In Worcester, the price tag shared by state and federal authorities already tops $50 million.

"We did what had to be done in Worcester and there's still a lot of work to do," says Clint McFarland, director of the U.S. Department of Agriculture's beetle eradication program. He hopes that the appearance in Boston was a localized, "human-assisted" one, rather than a case of insects moving from tree to tree on their own.

Because the ALB is not dependent on a single tree species and has no known predators, the beetle can devastate a forest ecosystem. It indiscriminately burrows into maple, elm, horse chestnut, ash, birch, poplar, willow, and other hardwoods. And the destruction it causes could mean billions of dollars to the lumber, wood products, maple syrup, and tourism industries.

For those who are running out to scour their backyards, know that the following are not host trees: oaks, conifers, and stone fruit bearers such as cherry, peach, and plum. Choose a sunny day (through December) and look for a three-quarter- to one-inch-long shiny, jet–black beetle with notable white spots and very long black-and-white banded antennae. Walk slowly around the tree trunk and if you spot what looks like ALB damage—a perfectly round dime-sized hole or divots in the bark—immediately contact your state USDA office. If you think you see an ALB, catch it in a jar and call the USDA , which can confirm its identity. To see pictures of the beetle and the damage it causes, click here.