Another 18,000 London property owners will be barred from moving ash wood as of next Monday.

And all of Middlesex County will soon be under a similar quarantine, likely by autumn.

All because the emerald ash borer -- a bug whose voracious appetite has destroyed tens of millions of trees in the U.S. Midwest -- has expanded its range.

Ken Marchant, emerald ash borer specialist with the Canadian Food Inspection Agency (CFIA), said the zone expansion is a result of finding infested trees in the Doon Drive and Carriage Hill Park areas of north London.

This new zone overlaps the existing quarantine area and expands it north.

Already, 56,000 London property owners within a five-kilometre radius of Greenway Park, near where infested trees were found, are barred from cutting or moving ash trees.

And worse is yet to come, as the ash-populous woodlots in Middlesex are under attack.

The CFIA is awaiting a ministerial order that would regulate, or quarantine, all the county's ash trees.

It hasn't happened yet because such an order entails a lot of planning as well as specific definition and enforcement language.

"Middlesex will be declared infested but it's the 'how' part and 'when' (that's still being decided)," Marchant said.

CFIA surveyors keep searching for the bug.

The quarantine expansion means big trouble for county tree nurseries, woodlot owners, loggers, firewood-sellers, sawmills and pallet makers.

"They need to be prepared" for restrictions, he warned Middlesex County council yesterday. "Emerald ash borer is putting companies out of business."

General regulations are being drafted that would allow companies within an infested zone in Canada to continue doing business, while ensuring they don't spread the bug.

If it's not controlled here, entire domestic and export industries dependent on this tree "will be lost," Marchant said.

The insect moves only about 500 metres a year on its own. But its migration is accelerated by people who move wood from an infested area to a clean one.

"If we can stop that, we can save millions of trees a year," Marchant said.

Already quarantined areas include Essex, Chatham-Kent, parts of Lambton Elgin counties and a large chunk of London.

In London, as many as 40,000 ash trees -- about 30,000 of them on private property -- are at risk.

Tomorrow, the City of London will hold a news conference to explain how it hopes residents will handle wood that may be borer-infested.

EMERALD ASH BORER

- Larvae feed exclusively under bark of ash trees (but not on mountain ash, which isn't a true ash).

- Believed to have arrived here in packing crates from eastern Asia about 15 years ago and first discovered in North America in 2002.

- Has since killed more than 20 million trees in mid-western U.S. and in deep Southwestern Ontario.

- No known native predators.

ATTEMPTS TO CONTROL THE EMERALD ASH BORER

- Felling and quarantining: Areas of Ontario and several U.S. states have tried this. It may have slowed the spread of the disease but not by much.

- Pesticides: London will try a natural pesticide on some of its 10,000 public property ash trees. Applying it wholesale to a woodlot of ash trees would be ecologically disastrous.

- Bug versus bug: This summer, researchers hope to release three tiny, parasite species of stingerless Asian wasps. Skeptics wonder if introducing a non-native bug to another non-native bug could compound the problem.