Basking in the sun on a juniper bush on a warm August day in 2001, the handsome inch-long insect was a glossy black dotted with yellow speckles. Its long antennae made two graceful arcs, rather like old TV rabbit ears. "I knew the moment I saw it that this was very, very bad," reflects John Muth. "The temptation was to squish it."
Fortunately, he put the beetle in jar and took it to the U.S. Department of Agriculture. As it turned out, Muth, the owner of Bonsai Northwest in Tukwila, Washington, was the unwitting recipient of the first citrus longhorned beetles (Anoplophora chinensis) to be introduced into the U.S. The insects had hitched a ride among 369 bonsai maple trees that Muth had imported from Korea, even though he had adhered to all U.S. import requirements.
A cousin of the tenacious Asian longhorned beetle--which since its initial discovery in 1996 in New York City has caused tens of millions of dollars in damage annually--the citrus longhorned beetle offers a case study in how aggressive, timely action can prevent exotic pests from causing large-scale mayhem in local ecosystems. The battle to stop this beetle also demonstrates the difficulties inherent in such an endeavor. It involved the destruction of otherwise healthy trees in homeowners' yards, and required the suspension of normal environmental regulations so that a rapid response could be mounted.
Exotic pests such as the longhorned beetle are a growing problem--an unintended side effect of human travel and commerce. Stowaway insects, fungus or other pests can travel vast distances to ecosystems that are unequipped to combat them. To cite just one infamous example, in the early 1900s the fungus and its beetle vector that are responsible for Dutch elm disease cruised across the Atlantic hidden inside European elm logs shipped to the U.S. They soon decimated the beloved American elm. Modern aircraft--which bring plant materials and other goods from thousands of miles away to any location in the world within hours--have only exacerbated the problem.
Despite stringent regulations, federal inspections and lengthy quarantines, the pests can still escape and wreak havoc. A 1999 study by Cornell University estimated that 50,000 plants and animal species have been introduced into the U.S. since the time of Columbus--with the overall cost in damage and control efforts estimated at $137 billion annually.
High on the list of most damaging introduced species are longhorned beetles. Like modern-day Trojan horses, the larvae from China, Korea or Japan may be hidden deep in wooden shipping pallets or in the trunks of trees. Beetles then emerge by creating a quarter-inch-diameter exit hole. Their lengthy antenna can stretch three inches beyond their inch-long bodies. Adults can fly up to several hundred yards to find a suitable host tree, and have been known to reach the rooftop gardens of 18-story buildings. Even in their native China, the Asian longhorned beetles have successfully moved from their original range in eastern China to northern provinces, where they have destroyed 80 million trees.
The citrus longhorned beetle potentially represents a greater threat than its more famous cousin¿the citrus is known to attack 40 additional species of trees and shrubs. Included among the known tree hosts are citrus species, fruit trees such apple and pear, and hardwood trees such as maple, poplar, elm, oak and willow. If that weren't bad enough, "citrus longhorned beetles could probably survive anywhere in the U.S. except Alaska," adds Robert Haack, USDA Forest Service research entomologist.
With this background in mind, Chad Phillips, a Washington State Department of Agriculture (WSDA) project entomologist, received the alarming news by phone. The response was swift. "Everyone grouped together for a few seconds, then we stuffed a bunch of people, nets and equipment in a truck," recalls Phillips. They arrived on Muth¿s doorstep in an hour.