Bees vs. mosquitoes

A line in a news release about mosquito spraying in Grand Forks tomorrow evening jumped off the page of the inbox this morning:



The insecticide used for the aerial spray is primarily used to control adult mosquitoes and black fly populations. Beekeepers are advised to cover their hives as this product can be toxic to bees. For more information call mosquito control at 787-8110.

Toxic to bees? Aren’t bees in a mysterious decline? Yes, and yes, but the city is also facing an outbreak of West Nile Virus — August is prime time for WNV — and that can be toxic to people over 50.

The city will use the U.S. Air Force to drop the pesticide on the city. The city buys the pesticide and the Air Force considers it part of its training and picks up the tab for the spraying, according to John Bernstrom, the communications specialist for the city of Grand Forks.

He says the pesticide being used is Trumpet. A search for it on Google reveals this nugget from the Oregon West Nile Virus Working Group:


This product can be applied by conventional ground based ULV applications, however it is best suited as an aerial applied adulticide. This product does not have setback restrictions to water, is labeled on over 25 crops and has a .5 ppm tolerance as established by the EPA for all crops. Naled shows little persistence in soil or water. This product is highly toxic to fish, bees and many aquatic invertebrates.

The company’s instruction for handling offers these guidelines:


This product is highly toxic to bees exposed to direct treatment on blooming crops or  weeds. To minimize hazard to bees, it is recommended that the product is not applied more than two hours after sunrise or two hours before sunset, limiting application to times when bees are least active. Do not apply this product or allow it to drift to blooming crops or weeds while bees are visiting the treatment area, except when applications are made to prevent or control a threat to public and/or animal health determined by a state, tribal or local health or vector control agency on the basis of documented evidence of disease causing agents in vector mosquitoes or the occurrence of mosquito-borne disease in animal or human populations, or if specifically approved by the state or the tribe during a natural disaster recovery effort.

Grand Forks complies with that advice by starting spraying at 7:30, about an hour before sunset. That’ll help, but bee experts in Florida say aerial spraying will kill bees because on particularly warm nights, they stay outside the hive to better ventilate the brood.

It’s a big issue, especially in Winnipeg, which is in the middle of deciding whether spraying for mosquitoes is worth any environmental damage. For guidance, the CBC turned to Grand Forks recently.


According to Todd Hanson, who is in charge of mosquito control just across the U.S. border in Grand Forks, N.D., that city uses permethrin — a biological adulticide that is safer for workers than the malathion Winnipeg uses.

“I guess what I shake my head at is that the synthetic pyrethroids aren’t registered to be used in Winnipeg,” he said.

Grand Forks residents can also apply for a buffer zone, but no one has yet this year, Hanson said.

“And once we start getting into the elevated risk of West Nile virus, when we start seeing the Culex tarsalis [the mosquito type that carries West Nile], that option no longer exists,” he added.

The comments section of a newspaper article on the subject in Winnipeg shows the emotion the subject engenders:


It’s time for the city and province to realize this is something that the a vast majority (not even close) of Winnipeggers are in favour of. It’s time to stand up to the small minority of green freaks who’ve controlled this issue too long. We want fogging. Summer in this city is too short, and winter too long, not to have it.

Minnesota has a different approach. It uses helicopters to drop a natural soil bacterium to control mosquito larva. It does not spray pesticides by air. To the extent it uses pesticides, the mosquito control district in the metro keeps a record of the location of bee hives, according to Mike McLean, the district’s public information officer..

  • Zebulun

    Excellent work, Bob, but I think the Minnesota communities in the Red River Valley are spraying more pesticides than your column suggests. This is from the F-M Fight the Bite website:

    “The City of Moorhead provides seasonal control of mosquitoes by surveillance, trap counts, larviciding of wet areas and ditches, citywide ground spraying of adulticide and occasional aerial spraying.”

    And a recent public announcement in the Fargo Forum (09/09/10) reported that “mosquito spraying is planned Tuesday night in the Minnesota communities of Beltrami and Felton, according to Airborne Custom Spraying of Halstad.”

    And that’s on top of the pesticide soup that is already broadcast over the crop fields.

  • Bob Collins

    Excellent info, Zebulun. I erred and should’ve made clear that it’s not “Minnesota” that has a different approach to this, but it’s the “metro” area mosquito agency.

    Thanks for correcting.