Asian Longhorned Beetle Rediscovered Outside of Toronto

Asian long-horned beetle discovered in Mississauga

Asian long-horned beetle found in industrial park five years after the last invasion was eradicated in GTA.

JIM WILKES / TORONTO STAR

The Asian long-horned beetle, target of a determined effort at eradication, was declared expunged from Toronto and Vaughan but has re-emerged in Mississauga. 

By: Zoe McKnight Staff Reporter, Published on Wed Oct 02 2013

The troublesome Asian long-horned beetle has re-emerged, this time from trees in Mississauga, leaving its perfectly round exit holes and fears of another invasion.

The Canadian Food Inspection Agency (CFIA) said inspectors confirmed the pest’s presence northeast of Pearson airport in late September, after a person found one of the distinctive beetles on his car in August.

Twenty trees have since been removed and two have been confirmed infested, according to the CFIA. A 2.4-kilometre swath of land near the American Drive Business Park, an industrial park at highways 427 and 409, is being surveyed.

The Mississauga tree canopy could face disaster. According to a 2011 technical report prepared by the Toronto and Region Conservation Authority, the worst-case scenario would be costly: 56 per cent of Mississauga’s tree population is susceptible to the beetle, amounting to a potential loss of $702 million.

That’s why the invasive species is taken so seriously, said Gavin Longmuir, Mississauga’s urban forestry manager and co-author of the report, who was contacted by the CFIA in September.

“You can imagine if that insect got out into the larger open forest north of the city or west or east and how that would have a huge impact.”

Actual damage would likely be less severe, the report states. The beetle attacks hardwood species and is especially fond of maple, but will settle for elm, birch, poplar and mountain ash trees, among others.

Larvae burrow in the trees and leave dime-size holes when they emerge as adults with blue-black and white-spotted bodies three centimetres long. The larvae feed on the green inner bark and those exit holes leave the tree structurally unsound and unhealthy. An affected tree can be dead within a few years.

The exact scope of the infestation is yet to be determined, Longmuir said.

In April, the federal Agriculture department declared the pest eradicated from Canada. It was last detected in late 2007, and first noticed near the Vaughan-Toronto border in 2003.

Nearly 30,000 trees were removed from affected areas in the GTA. In some cases, all susceptible trees within a 400-metre radius of an infected tree were chopped down.

But this invasion is likely new and not a continuation of the old one, said Gregory Wolff, the CFIA’s chief plant health officer.

A property manager with Bentall Kennedy, which runs the American Drive Business Park, said one maple tree was cut down on site but was not aware of a larger problem. It was not immediately known how the beetles were imported.

The beetle is native to East Asia and has no natural predators in Canada. It can fly only short distances and typically moves with the transport of cut wood, fire wood and wood packaging materials. The CFIA is asking the public not to move firewood.