Keeping black flies under control

Jodi Schellenberg
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People call them no-see-ems, gnats and black flies but by any name the Black Fly Control program is on the case.

Left: Shawn Meckelborg, the Black Fly Control program co-ordinator, looks at one of the monitors to see how many black fly larvae are in the river on Wednesday. Top right: Sample shows how many larvae were in the river one week before treatment. Bottom right: One week after treatment, there were substantially less larvae in the river.

A river tour program of the North Saskatchewan River and overview of the Black Fly Control program was provided by District 32 Agriculture, Development and Diversification Board (District 32 ADD Board) on Wednesday morning.

Before heading down the river to look at some of the black fly monitors, program co-ordinator Shawn Meckelborg spoke about the importance of the program.

Every year the program is funded through the Government of Saskatchewan’s Ministry of Agriculture and delivered by the Add Board. It has been going on for about 30 years.

“One of the big motivators for the program was a study that was done in 1975 to try to estimate what the cost to the producers was of black flies,” Meckelborg said. “They looked at calf weights, how many were bunching up, stampeded activity and replacing fences.

“It was in the area of $3 million that was each year. That was in 1975 so you can imagine what it would be now.”

The livestock numbers in the area have varied since 1975, with a decrease in numbers because of mad cow disease more recently, but back then they also didn’t have the variety of livestock now seen, which would contribute to higher numbers.

The program starts as soon as spring breakup happens, Meckelborg said. Once the ice clears, he will get on the river, setting up his monitors every couple of kilometres.

Instead of trying to control the flies at an egg or adult stage, they treat the water to kill the larvae since the eggs are too well protected by mud to be treated.

Black flies spawn in moving water instead of stagnant sloughs or ponds.

“The (larvae) have to be in the (flowing) water because they have no means of mobility to go get their food,” Meckelborg said.

In order to feed, the larvae attach to vegetation in the water, using tentacles to grab food.

The monitors are used to see how many larvae are in the water and tell Meckelborg when he has to treat it.

Monitors are used instead of vegetation in order to observe consistently.

He uses a block as an anchor on the bottom, a jug marked as a monitor to float on the surface, with a second rope attached to another anchor. On the rope are two one metre long strapping tapes that mimic vegetation for the larvae to attach onto.

When he is checking the monitors, he will take off a piece of tape and put it into a solution of alcohol and water to count how many larvae are in the water. If the number is too high, he will then treat it.

Occasionally the river will rid itself of the pests in certain situations.

“The South Saskatchewan is going through a flush, it will knock those larvae off (the tape) but more than anything it will scrape the bottom and take that vegetation out so they have no habitat,” Meckelborg said.

Most of the time they have to treat the river to eliminate most of the larvae.

“This is a control program. It is not an eradication program. We are not trying to wipe out black flies,” Meckelborg stressed. “We couldn’t if we wanted to. If each female can lay thousands of eggs, they can repopulate an area really quickly so basically what we are trying to do is get it so those livestock producers can (do) most of the calving.

“They do the calving in the spring and have enough time for the calves to get stronger and have some weight gains and be able to fend for themselves,” he added.

To treat the larvae, they use a product called BTI, which is a bacterial pesticide.

Unlike chemicals they used more than 25 years ago, which killed the water’s natural ecosystem including fish, BTI is not a poison and is considered non-toxic to other life forms.

“Basically the larvae are going to eat it and it is toxic to them,” Meckelborg said. “You are not really putting in anything that isn’t in the environment -- it is already there, we are just bumping it up to a level that controls them.

“It is really target specific,” he added. “It only goes after (black flies) so it doesn’t harm any other natural predators of the black fly in the water. It is wonderful to work with. We treat in shorts, T-shirts and sandals as opposed to what we used to do with the full hot gear all the time.”

Although they cover five rivers in the area -- including both the North and South Saskatchewan Rivers and the Torch River -- since it is a wet year there may be other creeks where the black flies may spawn.

Since they have to get a permit early in the year, they cannot treat the smaller rivers and creeks, such as Little Red.

It is also an expensive program. BTI costs $16 per litre and they spend about $60,000 each year on the pesticide.

Organizations: ADD Board, Development and Diversification Board, Ministry of Agriculture North and South Saskatchewan Rivers

Geographic location: North Saskatchewan River, Saskatchewan, South Saskatchewan Torch River Little Red

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