Posted December 30, 2016
by Hilary



There’s nothing worse than discovering your bees have been poisoned. The once busy entrance, now silent with only a few twitching bees in carpet of dead below. The suddenness of a colony lost to pesticide poisoning is shocking. What follows is often heartbreaking, humbling and infuriating. So, how do you know if your colony has been poisoned? What do you do if it happens and how can you prevent it if it hasn’t yet? Read on to find out everything you need to know about how to protect your bees and other pollinators from this terrible ordeal.

Recognizing Pesticide Poisoning

Since honey bees will fly up to three miles to forage, urban beekeepers are particularly at risk form pesticides. Unlike agricultural settings, most urban and suburban homeowners are free to use pesticides without restrictions, licensing or instruction. If one of your neighbors uses a pesticide improperly, it can devastate nearby beehives. The improper use of a pesticide can include: using too much, applying it to plants when they are in bloom, or applying it at the wrong time of day. It’s important to understand that the majority of these incidents happen as a result of ignorance, not malice. Many simply fail to read instructions before using the product they buy and do so without an understanding of the consequences their actions have.

When your colony experiences acute pesticide poisoning, you will see:

  • A sudden drop in foragers.
  • A large mat of dead bees in front of your hive.
  • Spinning, skipping and disoriented bees on the ground around your hive.
  • Bees dropping from the frames when you lift them out.
  • Dead bees on the bottom board.


How to Help a Poisoned Hive Recover

Unfortunately, most poisoned hives never recover, but in most cases it is a simple numbers game. The bigger your colony is, the better it’s chance of survival. Once pesticides knock out the field bees, the population will be drastically reduced. A hive with a low population is now at risk for a number of other problems because it will not have the necessary workforce needed to complete daily tasks.

One big one is cleanliness. A poisoned hive an easily become overwhelmed with the housework or cleaning out dead bees and any poisoned larvae. You can’t do much to help dead larvae in the cells. If you notice a particular comb that does not appear to be occupied anymore and it contains dead larvae you should consider pulling it out of the hive. If you find dead bees on the bottom board, be sure to clear them out of the hive to prevent any secondary bacterial infections from taking hold. It is a good idea to check your bottom board every few days after a poisoning if the bees seem overwhelmed with dead bodies.

Another big problem is food stores. Without foragers, your bees will be forced to live on what they have. If their stores are low, they can end up dying of starvation! Make sure your bees have enough pollen and honey stores and if they do not you should feed them until they can build up their population again.

It is very common for a colony that has been poisoned to end up queenless and it does not always happen right away. You should take special care not to overlook the symptoms of a colony that has lost its queen. If you notice your bees are making new queens, you should let them or replace her yourself. It is likely that your queen has been damaged or killed by the pesticide exposure. In most cases, a colony will have a better chance of survival if you requeen them. I usually wait several weeks after the poisoning before doing this to be sure they have a shot at survival.

As a general rule of thumb, I recommend you reduce the entrance whenever a colony is weakened to protect them from predators. Be sure to do this when your colony is recovering from a poisoning as well as they will be extremely vulnerable.

Another important thing to know is that a colony whose population drops suddenly can also fall victim to mites, moths and beetles. Keep a close eye out for these villains in the weeks following the poisoning and take appropriate action against them if you see any signs. It’s a good idea to head off moths and beetles by removing any abandoned comb. A weakened colony may not have the resources to defend all of the combs they once occupied. When mites take hold it can be a tough choice for how best to help the bees. Doing nothing will surely mean collapse, but most mite treatments will be too harsh for a colony weakened by pesticides. Each case deserves its own unique solution. My preference is to requeen, shake powdered sugar and to add capped brood and nurse bees from a stronger hive to increase the population.

Lastly, you will need to be patient. It will take months for beehive to recover from poisoning if they don’t die outright. Even though there are things you can do to help them, time is the biggest healer. Make sure you are not opening your hive too often, you will only hinder their recover. In this situation, having a viewing window on your hive can be extremely helpful. It will allow you to check the bees without disturbing them.


A Case Study

The above are photos of a student’s rooftop apiary which was poisoned in July of 2016 and exhibited all of the above symptoms and obstacles to recovery. Her two new colonies were thriving and just beginning to fill their second brood box with honeycomb when disaster struck. Nearly all of the foragers were poisoned. Many of them never made it back to the hives, but several hundred did and unfortunately, they passed on the poison to the house bees. When this happens, you will find dead bees inside the hive and young bees will drop off the frames when you lift them out. At this stage of poisoning, a colonies’ chance of survival is minimal. In this particular case we have managed to keep both colonies alive so far (it has been five months), but it took a lot of effort and the bees still have not fully recovered.

Initially, both colonies had little to no foraging activity and struggled with the house chores because of a reduced population. Their population was less than half of what it was. We moved quickly to reduce their hive cavity, pulling out combs they had abandoned. We began feeding them and we waited. After several weeks, the mite population spiked dangerously. We dusted the bees with powdered sugar  to increase mite drop and decided to requeen one of the hives. Normally, I would have requeened both hives, but we decided to experiment. Hive A accepted the new queen and began to improve, but still lacked the necessary population to make their recovery. We ended up heavily subsiding their population by adding several frames of capped brood and nurse bees from one of my own large strong colonies. The same was done for Hive B which was not requeened. Hive A is now improving slowly, but surely, while Hive B continues to struggle. Hive B reccently requeened themselves successfully and we hope the new queen will turn them around, but we continue to monitor them closely.

Below is an example of a flyer I distribute to neighbors after a poisoning incident in hopes of preventing it from happening again. One of the worst parts of losing a colony to pesticide poisoning is the knowledge that it can easily happen again. Your best chance is to take action and educate your neighbors about pesticide use. If you can speak to your neighbors in person, it will be more affective, but it is good to leave them with something they can refer back to. It’s an even better idea to hand out a modified version of this flyer before a poisoning incident occurs.

Poisoned bees flyer

Preventing Pesticide Poisoning

We cannot control where our bees go to forage, but what we can do is educate our communities about protecting our pollinators with responsible pest management practices. Some strategies for reaching your neighbors include: door-to-door canvassing with educational pamphlets, posting on online community forums, contacting local leaders or news organizations, and volunteering to speak to garden groups. Here is some useful information to share when employing these outreach strategies.

Pesticides are not always necessary. When a plant is under stress, it’s susceptible to pests and other problems. When you use a pesticide or a fungicide you are really only treating a symptom and not the problem. The problem often lies in the soil. Poor soil health leads to weak plants which leads to pest problems. So, before dousing your plant in pesticides, you might want to investigate whether the soil needs to be amended.

Pick your poison carefully. Some pesticides are more harmful to bees than others and even the ones that are less harmful can still do damaged when applied incorrectly. If you feel that you need to use a pesticide, research which ones are most appropriate and least harmful to the bees. Most people do not realize that organic pesticides will still harm bees.

Application matters. Always read the directions on your pesticide product, but in general to protect pollinators, you should not treat plants that are in bloom. It is also important to apply the pesticide in the evening so that it is less likely the bees will encounter it and you should not apply the pesticide in windy or wet conditions because this can lead to drift.


  1. Susan Rudnicki

    It is a devastating experience. I have had a nuc, full to the brim and ready to sell, be stricken by poisoning till the colony population fell to about 200 bees and the queen. I boosted them with frames of capped brood and they recovered in 2 months.

    All my colonies—28—are feral survivor stock. One tall stack, kept at my house, has actually had TWO incidents of pesticide poisoning—July of 2014 and December of 2015. Both times, the pool of dead bees out front, the dead on the bottom board, the bees dropping off the frames and flipping around on the ground were the cardinal signs of acute poisoning. All signs became clear over the course of a day, but the initial recovery—the continued acute dying—took about 10 days to run its course. I do not think this colony would have survived but for their bulk size—3 deeps—contributed to a larger population to absorb and dilute the poisoning. The queen was not poisoned either time, and I attribute that to the fact that bees handing off any food to the queen are not the usual bees receiving nectar as it comes in.
    I strongly urge anyone keeping bees to make use of Michele Colopy at the Pollinator Stewardship Council in her effort to collect and report poisoning incidents to the government agencies. All you have to do is submit some photos of the carnage, a description of what happened and she does the rest, the filing of the official reports to the Dept of Pesticide Regulation in your state and the report to the EPA. Here is the note she sent me after I wrote her of my hive’s second poisoning. If we do not report these things, it is the tendency of the agencies to say “nothing is happening”
    This kind of thing does not help our cause to rein in pesticide usage.
    Dear Ms. Rudnicki,

    The Pollinator Stewardship Council has been encouraging beekeepers to report their bee kills (not winter losses, that is BIP’s work) since 2013 . We worked with the Honey Bee Health Coalition in May 2015 to create a guide on how to report bee kills due to pesticides. The attached article was printed in Bee Culture magazine, and the attached Quick Guide PDF was there as well. Beekeepers can request a laminated copy of the Quick Guide at

    Thank you for your due diligence in reporting your losses. It is only through awareness and data collection that we all can gain a better understanding of all of the factors (pests, pathogens, pesticides, and poor forage) affecting our honey bees whether it is 2 hives or 2000 colonies damaged or killed.

    Even though EPA has stated they do not like to accept “second-hand” reports, such as from the Pollinator Stewardship Council; EPA doesaccept “second-hand” reports of pesticide incidents that were reported to pesticide manufacturers. When you and I spoke about your bee losses, I simply wrote down what you told me; you reviewed and approved the report, and gave me your permission to email the reports to CDPR and to EPA with your name and contact information in the report. (beekeepers can report their losses anonymously, and we will respect a beekeeper’s privacy to do so.) The Pollinator Stewardship Council is here to assist beekeepers in the reporting process. Our goal is to listen to beekeepers, explain the reporting process, and help them document their losses.

    At this time the Pollinator Stewardship Council is part of a committee, along with other concerned nonprofits, working with EPA to revamp their incident reporting data collection.

    Through more than 50 presentations around the U.S. the Pollinator Stewardship Council has provided information about reporting bee kills due to pesticide exposure, and encouraged beekeepers to report their losses. We need all beekeepers to report their losses (winter losses to Bee Informed Partnership as that data collection is important), and losses as a result of pesticide poisoning to the Pollinator Stewardship Council, EPA, and the beekeeper’s state EPA as this data is just as important in helping to improve the health of our bees. See reported losses at

    I am very sorry for the losses you have experienced. Thank you for taking the time to report this incident. Please feel free to share this information with your beekeeping network.

    Michele Colopy
    Program Director
    Pollinator Stewardship Council, Inc.
    P.O. Box 304
    Perkinston, MS 39573

  2. Lee

    One of my strongest hives was poisoned back in October, so this is a rather timely article. It’s reassuring to see I carried out all of your suggestions! When the poisoning occurred, I scoured the internet for information, and I found very little. I’m actually going to inspect them later this morning to continue some post-poisoned care.

    I really like the inclusion of the case study and flyer examples that you’ve included with this article. I live in a rural, farming community, so I’m not sure how my neighbors would take to receiving them. However, it is an excellent idea I will consider in the future.

    ps. I hope to see more interviews with female beekeepers again soon 🙂

  3. srdoerd

    How do I tell the difference between pollen & uncapped honey?

    • Hilary

      Pollen will usually be brightly colored and the bees do not cap it. You might benefit from taking my online beekeeping class. There is a whole section on how to ID what you are seeing in your hive. https://VIMEO.COM/ONDEMAND/GNDHONEY

  4. Kaya

    I’m curious, if a hive is poisoned and survives can you ever harvest Honey from them or reuse the hive? Or should all the honey and any future honey from that hive be considered contaminated and not consumed.

    • Hilary

      I trust the bees in this matter. If they seem to abandon comb that they had during the time of the poisoning I will take out those combs.

  5. Colin Purrington

    Were these bees killed by pyrethroids, by chance? Am looking for a photograph of dead bees killed by neighbor’s mosquito spraying.

    • Hilary

      We don’t know which pesticide it was.

    • Greg

      You can send a sample free to USDA . They can give you a list of what poisons are in your samples. There is no cost for them to evaluate the cause of death . They will give you instructions on how to gather specimens and how to ship.

  6. David Felker

    Do the “mosquito dunks” that are used to kill mosquito larvae in standing water cause problems for the bees if they drink the water? The packaging says it is harmless to anything other than mosquitos, but I always wonder…

    • Hilary

      I am not sure. I use mosquito fish instead.

  7. Scott

    What should be done with the frames and hive boxes of poisoned hive that has died out. We were planning to burn the foundation and comb.

    • Hilary

      I would burn it all.

  8. Tim Kendall

    I suspect my 2 hives and my neighbor’s 4 hives were poisoned. We didn’t know it at the time but suspect it. Some dead bees on the bottom board. No bees left in supers or even in hive body. No queen. Honey abandoned in supers. In July, I noticed a large number of my bees crawling around on the grass in front of the hive and then were dead the next day. A very strong hive and this went on for days.

  9. Laura M. Ford-Marchelos

    I’m pretty late to this “party”but relieved beyond words to find some sort of support and information regarding this.My hive was poisoned three weeks ago.I have a Warre hive with windows.The surviving bees are now scrunched up in the top box,which is full of honey TG.I have no idea if the queen made it,but it’s looking less and less likely. I can requeen,but should I also buy more bees?How do I do a paper combine-move the honey and top feed?I REALLY need some advice.
    There are two boxes lovely drawn comb below the honey.Please help-trying to save them!yours kindly,Laura



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My name is Hilary Kearney. I’m the author of the book, “Queenspotting” and founder of the urban beekeeping business Girl Next Door Honey in San Diego, California. I’m an artist turned beekeeper on a mission to help new beekeepers succeed and educate the public about the magic of bees!

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