An armyworm infestation in the Alberni Valley has caught the attention of a B.C. Ministry of Agriculture entomologist who is setting pheromone traps on local farms to monitor the lifecycle of the moths.
Entomologist Tracy Hueppelsheuser, based in Abbotsford, was in the Alberni Valley on Wednesday to talk with more than 40 local farmers about armyworms and what is being done by the ministry.
“We don’t have armyworms in the Fraser Valley, we haven’t seen this happen to our hay fields so it seems to be fairly limited to this area of Vancouver Island,” Hueppelsheuser said.
“[Armyworms] actually blow in from Mexico or the southern United States on wind in April or May and then the moths drop out of the clouds and find a nice lush patch of grass and lay a ton of eggs,” Hueppelsheuser said. “It’s a little bit of a roll of the dice to know where they’re going to land.”
As far as she’s heard, Hueppelsheuser said the moths don’t blow in over winter months in Canada.
Pheromone traps are being set up on Valley farms where armyworms have been identified.
“We’ll watch [the traps] through the next few weeks. What I expect will happen is we’ll get this peak of flight and we will get some more larvae in August and then I don’t know if we’ll see more moths after that or if they’ll die,” Hueppelsheuser said. “The traps are one of the tools that are going to help us figure that out.”
Next spring, Hueppelsheuser hopes to put more traps out in April and May to catch early warning signs of armyworms returning. The traps are a monitoring tool and not a control tool.
Parasitic wasps have been ordered to elevate armyworms as a biological control agent.
Wasp eggs come on a card, which is good for one acre of land. Inside the eggs are baby wasps that are pupating. Once they come out of the egg, the wasps search for a place to lay their eggs which Hueppelsheuser says they do inside armyworm eggs.
“They will put their egg inside the armyworm egg and the armyworm egg basically gets destroyed by the wasp,” she said.
Hueppelsheuser said there’s no way to predict armyworms coming onto your property. She said they like lush, green grass, cereals and hay but tend to not eat clover or vegetables.
“Another unique thing about these guys is they occur in clumps…that’s fairly unique for this group of insects. Moths lay lots of eggs in dense areas, lots of eggs per metre and then the larvae hang out together and then they pupate,” she said.
To identify armyworm moths, Hueppelsheuser said they have a white dot on each of their wings.
“Usually with a cutworm species like this, once we hit peak moth, you’re going to have tiny worms within weeks. I would say everyone should be scouting their fields or around those fields…for new larvae by mid August,” she said. “If you get five larvae per square foot you may have a problem.”