Honeybees are highly complex, social pollinators that can travel miles from their hives in search of nectar and pollen. In their search, they can also bring back pesticide residues. They can build up in hives and cause harm to the eggs, larvae, and adult honeybees. When things start going bad, it can be difficult to find the cause of the problem.

How can honeybees become exposed to pesticides?

• Bees may come into direct contact with spray or drift.
• Pollen-collecting hairs can pick up pesticide residues.
• Bees may drink contaminated water or nectar.

How can a backyard beekeeper reduce pesticide risk?

• Inspect hives regularly. Knowing how your honeybees look normally can help you identify problems faster.
• Keep bees healthy and vigorous. Ensure a clean source of water, proper pollen nutrition, and minimize hive disturbances.
• Communication is key. Pollinators can travel to many different backyards and that can mean a lot of potential pesticide exposures.
• Winters can get very cold. Consider your options to keep honeybees from freezing.
• Before controlling backyard pests, do some homework. For example, aphids secrete honeydew, a sugary liquid that attracts honeybees.
• You can consider non-pesticide or least-toxic alternatives when controlling pests.

Honeybees typically live only 5-6 weeks. It is normal to see dead bees in or around the hive. Honeybees remove the dead bees and throw them away from the entrance. However, pesticide poisonings can cause large numbers of bee deaths, resulting in piles near the hive.

Some signs that pesticides may be involved with bee deaths:

• Increased aggressiveness
• Paralysis
• Abnormally jerky, wobbly movements
• Spinning rapidly on their backs

Some pesticide effects may not be lethal. Pesticides may affect bee development or behavior.

If you suspect pesticides poisoned your bee hive(s), call your state’s pesticide regulatory agency right away. The sooner they can investigate, the better your chances are of finding out what happened.

Additional Resources:

• Protecting Bees and Other Pollinators from Pesticides - US Environmental Protection Agency (EPA)
• How to Reduce Bee Poisoning from Pesticides (Mobile App)- Oregon State University
• Bees in the Neighborhood: Best Practices for Urban Beekeepers - University of California, Ag and Natural Resources
• Bee Precaution Pesticide Ratings - University of California
• Common Organic-Allowed Pesticides - Xerces Society
• Organic Pesticides: Minimizing Risks to Pollinators and Beneficial Insects - Xerces Society
• Minimizing Honey Bee Exposure to Pesticides - University of Florida Extension
• EPA-registered Pesticide Products Approved for Use Against Varroa Mites in Bee Hives - US Environmental Protection Agency (EPA)
• Label Review Manual-Ch. 8: Environmental Hazards - US Environmental Protection Agency (EPA)
• Pollinator Protection Outreach Materials - Association of American Pesticide Control Officials

If you have questions about this, or any pesticide-related topic, please call NPIC at 800-858-7378 (8:00am - 12:00pm PST), or email at npic@ace.orst.edu.