U-pick farms feeling the sting during intense wasp year

Mario Bevilacqua is proud of his organic growing practices on his U-pick farm southwest of Edmonton, but he's having a hard time getting rid of the wasps invading his farm this year.

"Some of the raspberries have been all eaten by wasps. I thought it was ants, but no, it was wasps," he said Tuesday.

The hobby farmer says about 35 per cent of his strawberries went to the wasps this year, while 70 per cent of his honey crop was eaten by wasps, too.

"I'm supposed to get 1,000 lb. of honey," said Bevilacqua. "I'm going to lose some beehives because they're going to steal the honey."

To save the hives, he's making the entrance to the boxes smaller to keep the larger wasps out.

Royal Alberta Museum entomologist Matthias Buck says the culprit in this case is the bald-faced hornet.

"They're a little bigger … and a little bolder and they try to get into the hives. Other kinds of yellow jackets wouldn't usually do that," said Buck, who is assistant curator of invertebrate zoology at the museum.

Alberta has 14 yellow jacket species, but Buck says only a handful are known to crash barbecues in urban areas. Buck said the insects are looking for sugary snacks like ripe berries and honey to eat.

"That's basically their only food … carbohydrates, sweet stuff," said Buck.

The insects also go after grubs and mites to feed their young protein earlier in the season.

Buck said we're seeing more wasps than usual in Edmonton this year but it's just part of the natural population fluctuation insects go through from year to year.

Wasp nests grow quickly in part because hotter weather makes it easier for the insects to forage building materials like fibres from weathered wood.

• ​43-yr-old man dies after single wasp sting, had no idea he was allergic
• Wasp stings a sore spot for Deer Lake garbage collectors

Tim Darragh, owner of Big Rock Berry Farm near Spruce Grove, says nest hunting is a big part of their annual preparation before opening to the public.

"Our biggest concern is the safety of the customer … the last thing we want to have is a kid pick up a berry with a wasp in it," he said.

Bevilacqua said he had relatively good success trying to drown the nests in his field with water.

Ultimately, Buck says there's not much you can do to get rid of the insects.

"Don't spray your fruit, because you don't want to poison yourself," he said. "When the harder frost hits it basically kills the nest and then they're gone. Only the young queens overwinter and they start the cycle anew in the spring."