INHS Reports November-December 1998

Bad Beetle Finds a Good Home

The Asian longhorned beetle (Anoplophora glabripennis) first gained notoriety in North America following its 1996 discovery in trees in Brooklyn and Amityville, New York. Much to the dismay of Illinois agricultural and forestry officials, during the summer of 1998 it was also detected in two Chicago neighborhoods and in an unincorporated area of DuPage County. Asian longhorned beetles are native to China, Korea, and Japan, where outbreaks frequently ravage stands of poplars, maples, and willows. Unseasoned wood cut from infested stands is commonly used to construct shipping crates and pallets. Larval stages of the beetle can readily survive in transoceanic shipments burrowed deep inside larger crating timbers. Inside the wood they transform into the pupa stage and later change into the adult stage. The adult beetle will then chew its way out of the wood leaving a large circular hole.

The Asian longhorned beetle poses an especially serious threat to our urban and forest trees. Its geographic range throughout Asia suggests that nearly all of North America, from the Great Lakes to southern Mexico, could be colonized. The host range of the Asian longhorned beetle encompasses the majority of trees commonly found lining neighborhood streets and populating our river-bottom forests. Maples, boxelder, willows, poplars, horsechestnut, locusts, elms, and mulberries are just a few of the many tree species attacked. Unlike most of our native longhorned beetles which develop in weakened or dead trees, the Asian longhorned beetle can develop in healthy trees.

Unfortunately, once a healthy tree is under attack, little can be done. Larvae can grow to two inches long and tunnel deep into the heartwood. Over time, repeated tunneling by larval infestations will weaken and kill the tree. The dime-sized exit holes left behind by emerging adults persist as irrefutable evidence of an infestation.

In both the New York and Illinois infestations, the current goal is eradication. Thus far, the infestations seem to be limited in scope and the adult beetles have a fairly short flight range. Nonetheless, eradication will take considerable time, effort, and resources. Living deep within infested trees, larvae are unreachable with conventional insecticide sprays. Repeated aerial applications of insecticides for adult suppression pose serious logistic and public health concerns in densely populated urban settings. Currently, quarantines are the first step in the eradication process. The purpose of a quarantine is to establish a legal boundary of infestation, which is based on survey results and the biology and behavior of the insect, to restrict the movement of beetles or infested materials into new, uninfested sites. Inspectors then painstakingly examine individual trees within the quarantine boundaries for evidence of egg laying or adult emergence. Any tree showing signs of infestation will be cut, chipped, and burned late in the fall when the larvae are inside the wood.

Eradication efforts in New York seem to have reduced the beetle's numbers, but at the cost of

The Asian longhorned beetle, Anoplophora glabri-
pennis.

several million dollars and several thousand trees. In Illinois the battle with the Asian longhorned beetle has just begun; even if eradication is successful, it will likely be at least a five-year effort. As drastic and costly as these actions may seem, they hold the best hope of preventing the beetle's spread out of the urban environment into rural, state, and federal forests. To prevent repeated reintroductions of this insect, agricultural officials are seeking stricter regulations mandating kiln drying or fumigation of crating materials that originate from infested areas of Asia.

Charles Helm, Center for Economic Entomology; James Appleby, University of Illinois

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