Today We Learn About: The Asian Long-Horned Beetle

The Asian Long-Horned Beetle is an insect that, as the name suggests, is native to parts of Asia. In recent years, this beetle has grown to be a nuisance to many trees in the United States as there are no adequate predators to diminish the beetle population, and many food sources to allow the beetle to thrive. The beetle has infested trees in Brooklyn and Amityville, New York, Worcester, MA and in Chicago, Illinois. The beetle favors trees such Maples, Horse chestnuts, Poplars, Willows, Elms, Mulberries and Black Locusts1. Asian Long-Horned Beetles have a very unique look, which has earned them the name “Starry Sky Beetle” in their native China. This named is earned by the dark color of their wing coverings, which are speckled with white dots.

The infestation problem associated with the presence of the Asian Long-Horned Beetle was first identified, in Brooklyn, NY in 1996. The beetle infestation in New York spread to Long Island, Queens, and Manhattan. In 1998, a separate introduction of the beetle was discovered on trees in the suburbs of Chicago, Illinois. Beetles were also detected in two separate New Jersey locations – in Jersey City in 2002 and in Middlesex/Union counties in 2004. In 2007, ALB was found on Staten and Prall’s Island in New York. Most recently, beetles were detected in Worcester, Massachusetts in August 20082. By April of 2008, however, both Jersey City and Illinois had stated that they had gotten rid of their infestations.

The Asian Long-Horned Beetle causes the death of host trees because of its reproductive nature. This has been outlined by the United States Department of Agriculture as follows; After mating, adult females chew depressions into the bark of various hardwood tree species in which they lay (oviposit) their eggs. Once the eggs hatch, small white larvae bore their way through the bark into the tree, feeding on the sensitive vascular layer beneath. The larvae continue to feed deeper into the tree’s heartwood forming tunnels, or galleries, in the trunk and branches. This damage weakens the integrity of the tree and will eventually kill it if the infestation is severe enough. Over the course of a year, a larva will mature and then pupate near the surface, under the bark. From the pupa, an adult beetle emerges, chewing its way out of the tree; forming characteristic round holes approximately 3/8ths of an inch in diameter. Many of these holes will appear on a heavily infested tree frequently accompanied by frass (sawdust) and sap oozing from the holes. The emergence of beetles typically takes place from June through October with adults then flying in search of mates and new egg-laying sites to complete their life cycle3.

A number of significant steps are being taken to eradicate and isolate the growing population of Asian Long-Horned Beetles. The first and simplest step that many municipalities are taking is to quarantine infected areas. In doing so, authorities are preventing the spread of Asian Long-Horned Beetles by people citizens who may not be aware that they are indeed spreading the pest. People are prohibited from removing wood materials from an infected, quarantined area in order to diminish the chances of the beetles escaping their previous home in search of a new, uninfected tree home. The problem with this technique is that it really does nothing to cure the problem. It acts as a sort of band-aid to control the problem actually addressing the fact that we need to be rid of the beetles themselves. All a quarantine can really hope to do is keep the beetles within a specific area, and all this will lead to in the long run is the spread of beetles within that area and eventually, the need to expand the area once the limits have been reached.

Another tactic that is being employed involves the cutting, chipping, and burning of infected trees. When an area is shown to be infected with the beetle, local trees are marked and inspected by certified tree removal specialists who are then put in charge of cutting the trees down. These chopped down trees are then put into a wood chipper, and the chips are burned. This effectively eliminates the threat of the beetle. Further, the remaining stumps are ground down to below soil level in order to add an additional layer of protection into the future. The problem with this method lies in the fact that it is possible to miss infected trees, and if the infestation is widespread, an entire cities tree system might need to be eliminated.

The most controversial method of containment is the use of insecticides like Imidacloprid. This is an insecticide that has many, many positive aspects. The manner with which the insecticide eradicates the Asian Long-Horned Beetle lends itself nicely to the purpose, because unlike spray on pesticides that lay on the surface of a plant, Imidacloprid is absorbed through the roots of the host tree, effectively making it so that every square inch of the tree is protected. In addition to the systemic absorption of the pesticide, Imidacloprid also has a wonderful track record of eradication. The chemical has been directly linked to Illinois’s removal from quarantine in August of 2006. These two reasons alone are sufficient, but when you add to these the fact that the chemical is not harmful to people or pets and that it has the ability to save thousands if not hundreds of thousands of our nations tress than it is plain to see that there is Imidacloprid is a viable and worthwhile resource in the removal and eradication of the Asian Long-Horned Beetle.

There is a case to be made against the use of Imidacloprid in the eradication of the Asian Long-Horned Beetle. Firstly, the chemical is new and is still being researched. It is, as far as we know, safe to humans and pets but many chemicals have been initially listed as such only to have this ruling reversed. In that sense, the jury is still out. The most compelling case to be made against Imidacloprid in eradicating the Asian Long-Horned Beetle is the fact that some have claimed that the chemical could be playing a hand in Bee Colony Collapse. This is a tremendous downside to the use of the chemical, and should surely be taken seriously. At this point, however, we have no conclusive evidence that this is the case, so until that evidence comes we are left with speculation.

The Asian Long-Horned Beetle problem is quite substantial across the United States, and the news media, while making us aware has lead to many people having unreasonable fears. With the use of responsible containment techniques and the use of Imidacloprid, we have so far been able to keep the problem under relative control. In the future, we should continue to do research on eradication methods, and tighten our controls so that we are never met with this sort of problem again. As of this time, the United States has taken steps to ensure that no more invasive species enter our shores. This trend should continue, and Imidacloprid should continue to be used when an infestation is detected.


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One response to “Today We Learn About: The Asian Long-Horned Beetle

  1. For more information about the Asian longhorned beetle, including to report suspected infestations, please visit

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