How to Protect Your Beehives From Mosquito Spraying Following a Hurricane
Keep up to date on which counties are scheduled to conduct mosquito abatement programs, who has been notified, and contact information.
September 27, 2018 6:18 p.m.: Robeson County and Brunswick County filed for aerial exemptions. Brunswick County is going to start October 1 and Robeson County is going to start spraying on October 5.
September 27, 2018: Things are moving rapidly regarding mosquito spraying in hurricane and flood-affected areas across the state. Unlike previous years with Fran and Floyd, the state is no longer handling spray programs; they are strictly handling advising.
A recent press release from Governor Cooper states: “Due to the increased populations of mosquitoes caused by flooding from Hurricane Florence, Governor Roy Cooper today ordered $4 million to fund mosquito control efforts in counties currently under a major disaster declaration.
Those counties include: Bladen, Beaufort, Brunswick, Carteret, Columbus, Craven, Cumberland, Duplin, Harnett, Hoke, Hyde, Johnston, Jones, Lee, Lenoir, Moore, New Hanover, Onslow, Pamlico, Pender, Pitt, Richmond, Robeson, Sampson, Scotland, Wayne, and Wilson.”
Spraying is initiated and coordinated by counties and municipalities. Beekeepers in those areas should immediately identify themselves to the county EOC (Emergency Management) and find out if they are in/near a proposed spray block and get details from their local government.
How beekeepers can minimize the effects on their hives
The devil is in the details, most of which are under the purview of local officials, but here are some things you can do to try and avoid any potential problems with managed beehives.
Register with DriftWatch: The best course of action is to be on the radar (literally) of the agencies who might be spraying so that they don’t do so near the apiary. The NC Department of Agriculture & Consumer Services (NCDA&CS) Pesticide Division have been in contact with all counties that are interested in having an aerial application to control mosquitoes. The county public health administrator has to file a request for a public health exemption with the NCDA&CS. As part of this exemption, they are required to give the dates of the application and what is being applied. Once the NCDA&CS receive and approve this request, the NCDA&CS will send an email directly to the beekeepers who have registered on DriftWatch in the treatment zone. If you have not voluntarily registered, they have no way to contact you.
Work with local agencies to minimize exposure and non-target effects: the two main factors that make any given pesticide toxic to bees are the level of exposure and the potency of the compound. To minimize exposure to bees, applicators can avoid spraying during foraging hours (e.g., spray at night or late evening). Since mosquitos mostly fly at night, this is also the most effective option to knock-down mosquito populations. To minimize the toxicity of the pesticide, officials can try to select pesticides that have a lower toxicity to non-target insects like bees. One of the more popular products that is used in these situations is naled, which is highly toxic to bees. You can be proactive by working with agencies in helping to make sure you know what product is being sprayed, when it is being applied, and how is it being delivered. An ounce of prevention is worth a pound of cure.
Moving the hives: while physically relocating your hives is the next best option, it is not always possible or practical. It requires the beekeeper to place a screen on the front of each hive at night (when all of the foragers are back in the hive), then securing all of the hive boxes together to avoid them accidentally opening during shipping. Move them to another location out of the areas being sprayed (see above), then remove the screens for the bees to resume foraging the next morning. You can then move the bees back to their original location once all spraying is over.
Cover the bees: this is clearly a last resort and not altogether effective. The idea is to cover the hives (e.g., with wet burlap) to prevent them from being exposed with the pesticide and preventing the bees from foraging. This approach is usually not possible for large apiaries and can cause bees to overheat or suffocate. While fairly impractical and can be worse than doing nothing, it may be the only option available to beekeepers who cannot be proactive by taking the steps above.
Following any spraying incident, it is important to check your hives to inspect for potential effects. (1) Identify the number of dead bees in front of or inside the hive. Having a handful of dead bees is normal this time of year since the populations are declining in preparation for the winter, but several inches of dead bees littering the bottom board is usually diagnostic of an acute pesticide exposure. (2) Monitor your colonies for varroa mites using a sugar shake. Mite levels are at their highest this time of year, and they can themselves cause significant population decline. Without taking some sort of action to control their numbers, colonies often succumb through the winter. (3) Observe the foraging bees for unusual behaviors, such as morbidity, inability to fly, or unable to right themselves. These can be sublethal effects of certain pesticides, but they can also be caused by several bee viruses (that are transmitted by the varroa mites). (4) Unite colonies with weak populations with others containing strong populations. Since acute pesticide exposures affect adult bees and not the brood, the brood from the depopulated colonies can help boost the strength of other stronger hives that will have a better chance at making it through the winter. Do not unite weak colonies with other weak colonies, since together they only make a larger weak colony rather than one strong colony.
Mosquito abatement is an important public health issue to mitigate serious disease and illness. Usually what is good at killing a mosquito is also good at killing honey bees. It is possible to both control the mosquito population while minimizing their effects on bees, but it requires some significant action on part of the beekeeper to coordinate with each other and local officials.
Additional articles and links
Re-published with the permission of Dr. David Tarpy, NCSU Professor and Extension Specialist (Apiculture): Entomology & Plant Pathology.