Gardens can have challenges like weeds, insects, or fungi that can harm plants.
Maintaining a healthy garden without pesticides can often be achieved by simply optimizing your garden's environmental conditions like sunlight, soil health, airflow, and proper watering.
Pesticides are typically applied when other methods of control have failed and the pest is causing economic damage.
Pesticides include insecticides, fungicides, and herbicides.
- Insecticides kill or damage insects. Depending on the mode of action and concentration, insecticides can be harmful or fatal to bees and other beneficial insects.
- Herbicides target plants and can kill off the flowering "weedy" plants many bees depend on as food.
- Fungicides kill or inhibit the growth of fungi. Fungicides may have detrimental effects on bee nutrition if they destroy beneficial yeasts or microorganisms in bees’ guts.
Uncertain if a pesticide is known to cause harm to bees? Read the label to determine its toxicity to bees. To find a label without the product in hand, look up the active ingredient on the internet or use the Minnesota Department of Agriculture's website on Pesticides & Bee Toxicity or Pollinator Lethal Pesticides. The page on lethal pesticides provides a comprehensive list of any pesticide registered in Minnesota with "a pollinator protection box on the label or labeling or a pollinator, bee, or honeybee precautionary statement in the environmental hazards section of the label or labeling."
Note that even if a pesticide is not labeled as toxic to bees, caution during application is still warranted. Much is unknown about pesticide effects on different species of bees and how pesticides can synergize with each other.
Apply pesticides only when necessary and to prevent them from persisting as residue in the environment. Target the specific pest while taking active steps to protect foraging bees, nesting bees, and other beneficial insects. Learn more about safe application of pesticides from the "Protect Pollinators, Read Pesticide Labels" handout (card is also available in Spanish). Being safe and judicious with the use of pesticides can benefit all local pollinator communities.
Learn more about protecting pollinators from pesticides from University of Minnesota Extension.
Learn More
Reporting a Honey Bee Kill Suspected to be Caused by Pesticides
While some honey bee death is normal due to individual bee lifespans, when 10% or more of the colony population dies in a short amount of time (often within a few days), then the problem may be due to exposure to a bee-toxic pesticide. Certain pesticides can cause an acute bee kill, which is a sudden, large number of dead bees inside or in front of the hive. In order to find out if the bee death was due to a pesticide, the dead bees, live bees, and the hive itself can be sampled to look for pesticide residues as well as factors that may make the colony more susceptible to pesticides or a cause a death that looks like a pesticide kill (e.g., chronic bee paralysis virus).
Losing bees to a pesticide is upsetting and frustrating. Ultimately, a long-term solution is fewer and more targeted pesticide applications.
If it looks like your honey bee colonies were affected by a pesticide and you would like to investigate instead of opening up an investigation with the state, see this Quick Guide to Reporting a Pesticide-Related Bee Kill Incident from the Honey Bee Health Coalition. This Guide covers different options for sampling or your own, working with your state, and reporting a pesticide kill to the EPA. If you do want to work with your state, contact them first before taking your own samples. Testing the bees yourself can lead to an invalid state-level investigation.
Reporting the the Minnesota Department of Agriculture (MDA)
If you suspect your honey bee colony has been acutely affected by a pesticide, you can report the bee kill to the MDA. Use the official pesticide misuse page to report the incident. Following your report, the MDA will open an official investigation and a trained pesticide investigator will visit your site to collect samples and determine if a pesticide was the likely cause of the die-off. There is no charge. From the MDA website:
An “acute pesticide poisoning,” for purposes of bee kill investigations, must meet the following criteria:
- The event must be reported to the MDA.
- Dead bees collected in/around the hive have non-beekeeper applied pesticide residues present at levels that could contribute to bee death.
- At the time of investigation there is likely 100 or more dead bees in/around the hive, for every live frame of bees quantified. If there are three or fewer frames of bees present, a minimum of 300 dead bees need to be quantified; if there are 10 or more frames of bees present, a maximum of 1,000 dead bees need to be quantified.
If the bee kill was determined to be due to a pesticide and the affected apiary site was listed on the BeeCheck website, then the beekeeper may be eligible for compensation.
BeeCheck and FieldWatch program
FieldWatch is a voluntary program that allows for pesticide applicators to view locations of specialty and row crops, honey bee apiaries, and other sensitive agricultural areas. BeeCheck is part of FieldWatch, allowing pesticide applicators to reach out to the beekeeper ahead of an application and take precautions near an apiary. Beekeepers can select to make their apiary locations viewable by the public, or only viewable to registered applicators.
Reporting a Bee Kill to the Environmental Protection Agency (EPA)
Even if you do not want to report a bee kill to the MDA, consider reporting it to the EPA to notify them of the problem. Beekeepers can request to be anonymous. If no beekeepers report issues to the EPA, it can look like there are no honey bee deaths due to pesticides.
No need to report a bee kill to the EPA if you open an investigation with the MDA as the MDA will report it to the EPA.
FAQ
My neighbors are fogging/spraying their yard for mosquitoes. Will that kill the pollinators in my yard?
The insecticides used in fogs or sprays used for mosquitoes or other biting flies can be very harmful to bees and other insect pollinators as well as other beneficial insects. The potential for drift to reach your yard will depend on the direction and speed of the wind. Depending on the insecticide used, residue from the spray could remain toxic to bees foraging on exposed flowers or caterpillars eating the leaves for several weeks.
They are spraying for mosquitoes in my neighborhood. Will it harm my bees?
There are times when it is necessary to spray for mosquitoes to protect the public from mosquito-borne diseases. With these programs, precautions are taken to avoid contact with pollinators, reducing but not eliminating risk to pollinators.
Find out more by contacting your local mosquito control district. Most districts will have information about spraying available to the public and want to hear your concerns. In the Twin Cities seven-county metro area you can contact the Metropolitan Mosquito Control District.
How can I be sure my pollinator plants do not have harmful pesticides?
Even if you ask someone working where you buy plants if a particular plant has been treated with pesticides that could harm pollinators, they may not know. Often, treatments can be applied before plants reach the retail market. It is best to buy pollinator plants from producers who have committed to making sure that their plants are not treated with these pesticides. You can also start many pollinator plants yourself from seed. Seeds can sometimes come with pesticide treatments already applied to the seed coating. Pesticides applied as a seed treatment require a colorant be added to the coating to indicate treatment and the color should be noticeable to purchasers, with a couple exceptions like fumigants on the seed. In addition, there should also be seed tag labeling to indicate what pesticide was applied.
Resources
Preventing and Monitoring Bee Kills from Pesticides
- Guide by Michigan State University How do I know if a pesticide is safe for bees? Five steps to protect bees from pesticides; also in Spanish: ¿Cómo puedo saber si un pesticida es seguro para las abejas? Cinco pasos para proteger a las abejas de los pesticidas.
- What to do if you suspect your honey bee colonies are harmed by pesticides from Michigan State University
- The Xerces Society for Invertebrate Conservation provides information and guidelines on pesticides and pollinators.
- Getting to Know Commercial Beekeepers
- Let's See it from Both Sides: Perspective of Farmers and Beekeepers on the Protection of Honey Bees
- Pesticides that are known to harm bees maintained by the University of California
- Guide on how to reduce bee poisoning from pesticides by Oregon State University
- Beescape allows beekeepers to enter a location to see how the surrounding land is used and receive an estimation for pesticide risk in that location
- Online courses Pollinator Protection for Pesticide Applicators and Pollinator Protection for Land Managers from the Managed Pollinator Protection Working Group and Michigan State University
- Pesticide Environmental Stewardship contains additional resources.
- National Honey Bee Survey pesticide sampling results from collection of bee bread from across the U.S.
Labs that Process Pesticide Samples
- Cornell University
- Gastonia USDA Lab
- Diagnostic labs and services for beekeepers
- List of diagnostic labs from the Apiary Inspectors of America