Asian Longhorned Beetle:

A Potential Invader of Minnesota

By Ed Hayes and Dennis Haugen

The Asian longhorned beetle, Anoplophora glabripennis, (ALB), is a nonnative pest that poses a serious threat to the forest ecosystems of the United States. The ALB could establish in suitable areas of North America from southern Mexico to the Great Lakes (Haack et al. 1997). These beetles aggressively attack living trees, which ultimately leads to tree mortality. ALB, native to China and Korea, has been transported to the United States in the wood of shipping crates from China and has been detected at warehouses across the United States. The first infestation was detected in the Brooklyn, NY during 1996 (Haack et al. 1996, 1997). In Chicago, an infestation was detected during 1998 (Poland et al. 1998). To limit new introductions, APHIS has a new regulation that requires any solid wood packing material from China be treated (heat, fumigation or preservatives). Other states may have isolated infestations that have not yet been detected! Learn the signs of an infestation and report any ALB activity!

female Asian longhorned beetle

ALB Basics

ALB prefers maple trees. Other known hosts include horsechestnut, elms, willows, poplars, and birches. A number of new tree species have been recorded as hosts in the U.S. including green ash, hackberry, sycamore, and mountain ash. Laboratory rearing studies by U.S. researchers suggest that the host range may be even wider.

ALB has one generation per year. New adult beetles chew round holes through the bark and wood to emerge between June and November, with peak emergence in July. Adults have a life span of 1 to 2 months. Females lay 30 to 300 eggs by chewing a niche into the bark in which she deposits an egg. Eggs hatch in one to two weeks. Larvae tunnel under the bark in the early stages, while later stages tunnel deep into the wood. Larval development usually takes 9 to 10 months, and over wintering occurs in the larval stage. The adults are large, glossy and black, with irregular white spots on their wing covers. See photo. The long, curved antennae are striped white and black. In this country, mature ALB take about a year to develop from the time when a female beetle first deposits her eggs.

Adult beetles seldom fly more than 200 feet if a suitable host is readily available, although they are capable of flying one-half mile. The ALB possesses a relatively low intrinsic dispersal rate. Initial attacks are usually high in branches in the upper crown. Succeeding generations infest lower branches on the same tree. Repeated attacks cause crown dieback and eventually tree death. The sequence from initial attack to tree death may take up to 10 years, depending on tree size and vigor. The low dispersal of this pest presents the opportunity for eradication to be successful.

ALB Infestations in New York and Illinois

Currently, five infestations are known in the New York area. The Brooklyn-Greenpoint infestation was found in 1996, and more than 2900 infested trees have been found and destroyed in the last 5 years (Table 1). About a month after the Brooklyn infestation was found, another infestation was detected in Amityville, about 29 miles east of the Brooklyn infestation. A third infestation was detected in Queens-Bayside during 1998. In 1999, two more infestations were found in Manhattan (4 blocks from Central Park) and in Islip (on Long Island, 11 miles east of the Amityville infestation). These five infestations are likely the result of one introduction into Brooklyn, with infested cut tree material (branches and trunk sections) subsequently being moved from Brooklyn (before ALB was detected) to initiate the other infestations. So far, over 5700 infested trees have been found in New York.

Currently, five infestations are also known in the Chicago area. The Ravenswood infestation was found in 1998, and more than 1400 infested trees have been detected so far (see Table 1). Due to the intensive media coverage of the Ravenswood infestation, two small infestations were reported by the public in 1998 at Addison (18 miles west of Ravenswood) and Summit (14 miles southwest of Ravenswood). These three infestations are thought to be independent, i.e., started from separate shipments from China. Two more infestations were found in Park Ridge during 1999 and adjacent to O?Hare Airport during 2000; these infestations are due to movement of infested tree debris from the Ravenswood infestation prior to 1998. So far, more than 1500 infested trees have been found in Chicago.

Table 1. Number of ALB-infested trees detected by location and year.

New York*
Queens  15856914740914
Manhattan   315220103
Islip   111113
NY Total122078495416406105785786
Ravenswood  837472100131422
Addison  41152058
Summit  8170025
Park Ridge   4307
O'Hare    23023
IL Total  886508128131535

*Year totals from May 1 to April 30.
** Year totals from July 1 to June 30.

Infestation data is updated monthly and can be found at:

Eradication Projects

The goal is to eradicate ALB from North America. Quarantine areas have been established around each infestation in New York and Chicago to prevent further movement of infested tree material. Surveys of infested neighborhoods and surrounding areas are conducted to find infested trees. Infested tree are cut and chipped. New York has relied on ground survey with binoculars to find infested trees. Chicago has used bucket trucks and tree climbers since early 1999, which has greatly improved their ability to detect infested trees. Trunk and soil injections of imidacloprid, a systemic insecticide, are being evaluated for effectiveness. Chicago implemented an operational project during 2000 that treated more than 11,000 host trees with imidacloprid. During 2001, an additional 35,000 trees were treated in Chicago, and 23,000 trees in New York. The goal is to treat all host trees within one-eighth mile of any infested tree.

You Can Help

Early detection of an infestation is critical to successfully eradicate ALB and to minimize the number of infested trees that need to be removed. Your assistance is requested to detect and report ALB.

The key signs for ALB are:

Asian longhorned beetle - female at top, male at bottom
  • Adult beetles are 3/4 to 1 1/4 inch long with jet-black bodies and white spots, and antennae that are 1 1/2 to 2 1/2 times the body length.
  • Oval to round pits are chewed in the bark of live trees, especially maples, by adult females and a single egg is deposited in each.
  • Round 3/8" diameter holes are made by emerging adults on trunks and branches.
  • Look for coarse sawdust around the base and in branch unions of heavily infested trees.

For more information on ALB, visit these web sites:


Haack, R.A., Cavey, J.F., Hoebeke, E.R., and Law, K.R. 1996. "Anoplophora glabripennis: a new tree-infesting exotic cerambycid invades New York." Newsletter of the Michigan Entomological Society 41(2-3): 1-3.

Haack, R.A., Law, K.R., Mastro, V.C., Ossenbruggen, H.S., and Raimo, B.J. 1997. "New York's battle with the Asian long-horned beetle." Journal of Forestry 95(12): 11-15.

Poland, T.M., Haack, R.A., Petrice, T.R. 1998. "Chicago joins New York in battle with the Asian longhorned beetle." Newsletter of the Michigan Entomological Society 43(4): 15-17.

Ed Hayes is a DNR Forest Health Specialist in Rochester, MN. Dennis Haugen is a Forest Entomologist with the USDA Forest Service, Forest Health Protection in St. Paul, Minn.