Dave Sullivan
Northern News Services

Yellowknife (Aug 24/01) - Help is on the way for Yellowknife's beleaguered birch trees.

The city is buying 200 special wasps from Edmonton, at a cost of $3.75 each, to take on the birch leaf miner.

Dave City employee Denis Jefferson collects samples of birch leaf miners. The samples are sent weekly to an Edmonton lab, as part of the city's war against the bug that like birch trees. The next step will be to import wasps from Edmonton that could help control leaf miner infestations. - Sullivan/NNSL photo

The wasps will be released in downtown Yellowknife next month, in a test to see if they are the answer to a pest that's draining nutrients from birch and poplar trees.

The leaf miners don't kill the trees, but (the trees) do feel a lot of stress, says Grant White, community services director.

"We're just going to release (wasps) in the downtown area and we'll monitor next year to see how far they're progressing, and see if we need to introduce more around other parts of the city," says White.

The wasps won't kill all three strains of birch leaf miner, also known as sawflies.

Once a week city workers collect samples of birch leaf miner bugs at a dozen locations throughout Yellowknife. They stick to flypaper-style pads left in trees.

The sticky traps are then sent to an Edmonton lab, where biologists hope to find out how effective the wasps will be.

"The traps will identify the types of birch leaf miner there are in the city," White said.

Adult wasps lay eggs on the worm's larvae. The following spring, newly-hatched baby wasps eat the larvae.

There is an easier but less healthy way to protect the city's trees. Pesticides could be sprayed, but during last year's infestation a child was hospitalized after pouring out a can of toxic pesticide at home.

The birch leaf miner has been in Yellowknife for about a decade, but seems to be getting worse, city officials have said.

Lathrolestes luteolator

- Since being introduced in Edmonton in 1995, the city's 20-year-old birch leaf miner problem has been dramatically reduced.

- The tiny parasitic wasp (L. luteolator) selectively attacks the most damaging species of birch leafmining pests.

- Edmonton was cured of its need for entrenched and widely practiced insecticide treatments.

- The rapid success of the wasp in Edmonton is attributed to its successful overwintering.