Bee Science with Dewey Caron: Honey Bees and Smoke

Smoke and Honey Bees

Dr. Dewey Caron

Hi, I'm Dr. Dewey Caron. I come to you from Portland, Oregon, where we are in the midst of another wildfire smoke advisory. I present another audio postcard in my once-monthly Beekeeping Today mini-series podcast, Bee Science, with Dr. Dewey Caron. This is the ninth installment in this series. In each episode, I seek to blend research, field experience, and seasonal content, focused on the why behind honey bee biology, behavior.

I welcome, as usual, your suggestions for timely topics.

Another wildfire smoke alert. Two-thirds of Oregon and Washington in drought conditions, try to limit breathing that yellow air. That's my jumping off point for this podcast. I'll discuss smoking our bees, our need to promote safety from starting any wildfires while inspecting our honey bees. And I will also cover what little we know about the effect of wildfire smoke on our bees.

Smoke from wildfires seems to be on everyone's radar this time of year. Protecting yourself and your apiary during wildfire season means prioritizing air quality, fire prevention, and defensive behavior. We are advised to avoid inspecting hives when heavy smoke is present, both for our lungs and for the good of the bees. Prolonged exposure to poor smoky air stresses bees and disorients their navigation, sometimes making them highly defensive. It is not good for us to exert ourselves lifting heavy boxes and inspecting colonies during higher air pollution events.

When you were learning to keep bees, did you also learn how best to start a smoker and the best means of smoking? Probably not. The bee smoker is a tool. Like all our tools, we can use it correctly, or we can abuse use of such aids. How should it best be used? In a word, sparingly. When smoking our bees, we need to get over the natural tendency to smoke, smoke, smoke. Something we might do when starting with bees, or in the summer, early fall, when colonies are big, and simply opening a colony releases the behavior of those soldier bees. Those are the ones that sting.

Smoker use is best when we have a properly functioning smoker. We want smoke. White, not blue, smoke. And just smoke from that funnel. Not fire, and certainly not hot embers.

If you were ever a Boy Scout or a Campfire girl, you learned to build a fire from below, starting with something easily combustible. Initially build a fire that is fully involved in the smoker cylinder, and then snuff it out, snuff out that fire with a material that provides a good volume of clean, cool smoke. That's easier said than done.

Have you ever participated in a smoker lighting contest at a field day? Or when you were learning bees, did your mentor make you start the smoker every time you and he—she—had a learning session? Practice makes perfect.

What did you hear or learn about the best fuel for the smoker? Different individuals, new to beekeeping or hardened veterans, have a favorite fuel that works for them. Work, in this sense, is of a natural untreated material that produces a cool, thick, white smoke and smolders slowly without an open flame; i.e., good volume, long-lasting, and not bothersome to you.

So what works? Cotton materials, old clean socks, preferably, t-shirts. Burlap, best when not treated for rodents. Dried grass clippings, straw or hay, of course, provided you're not allergic to them. And then the old standby, pine needles, pine cones, old dried punky wood, wood shavings, cardboard, from things such as egg containers or the core paper towel or toilet paper rolls. You need to avoid cardboard that has glue.

Smoking pellets, which you can purchase from bee supply companies or from the barbecue supply outlets are somebody's favorites. We ought to avoid chemicals, plastic, glues, or synthetic treatments.

Some like to add herbs such as dried lavender, mint, or hops for a pleasant-smelling smoke, or to add green grass at top to slow smoke release from a hot smoker. I know of a couple that use plant material, including marijuana.

You might see suggestions that so and so added to the fuel calms bees. Nothing actually does calm bees. But smoke can mask chemicals, such as the alarm odor released when a bee stings, and the sting remains embedded in your skin or fabrics of your bee outfit.

Whatever you smoke with, be sure to get a fire going in the cylinder before starting with your smoke source—the stuff—and then stuffing enough to accommodate your objective. You want a smoker to stay lit the entire time you are doing your colony inspection.

Following opening and removal of one or two frames, it's always good to check your smoker and push that fuel down. Sometimes that fire will burn out below the fuel and then the smoker will not, uh—the smoker fuel itself on top will go out and not provide that smoke that you need.

There are a bunch of good videos on smoker fuel. Kamon Reynolds, a prolific YouTuber from Tennessee, likes pine straw, and he illustrates how easy it is to start and how he manages the fuel. The reference I have is supplied in the end notes.

While inspecting, we recommend you smoke bees at any entrances before removing the top covers. Try to remove covers without scraping them and free the propolis seal and then lift the inner cover slowly, applying smoke at the oval hole opening, if you use an inner cover. And then your inner cover has that central opening and ahead of your removing that inner cover from the top brood box or if you're going into a super, place covers away from your feet.

After a quick determination of how strong the colony appears, smoke where you're going to place your fingers to lift that first frame. You might disperse the bees from the top bars, not as punishment, but as an advisory to the bees that you are entering their domain.

The first frame comes out slowly to avoid crushing or rolling bees, possibly injuring the queen, and then that first removed frame, if it is without brood, should stay out to permit easy removal of additional frames.

If there's any danger of robbing, as now we are here at the end of the season, uh the main robbing season, put the frame into another empty box which you should cover. An empty nuc box works as a temporary depository for that first frame. If it has brood, you might lean it against the hive to take out another frame towards the edge of the box, one that doesn't have brood. It's not a good idea to leave brood, especially frames with open brood outside for any time period.

Smoke subsequent frames where your fingers are going. No need to smoke the entire colony or the entrance over and over and over.

If colonies are big, or they are in a drought or snappy for any reason, cover the open box with a damp cloth, such as a towel or dishcloth. There's a manipulating cloth you can purchase that has a metal oval that fits over a single frame covering the open box on either side. You do position that over the frame you want to remove. This works better to avoid stings than continually smoking across those frames across that open box that you have.

Once you finish your colony examination, a very helpful smoker use is to move the bees off the tops of frames and the edges of the box so you reduce chances of crushing bees as you reassemble your hive to close it.

If in the spring you are clamshelling and looking for queen cells, you might also want to apply smoke to the bottom bars as you peer in uh on and underneath the top one. That will help move the bees away and you might more easily be able to see—are the bees preparing to swarm? Are they developing queen cells? Just a little smoke works a whole lot better than a lot of smoke.

So why do we smoke bees? The common language we hear is that smoke calms bees. Bees are calm generally, so why do we need to calm them? Well, of course, we are a potential predator invading their home. But a better explanation for why we smoke is that smoke changes bee behavior, and it moves them, so we avoid accidental stings, for example, to our fingers as we lift a frame. They tend to go away from the smoke.

When we initially smoke the entrance, you will notice that there are fewer bees at the entrance after we smoke it. These bees aren't those likely to sting. The soldier bees—those bees inside the hive that are not doing anything at the time you open your colony, those are the ones likely to respond to your hive invasion. Smoke changes behavior of these soldier bees.

The smoke causes more individual bees to retreat and to seek liquid honey to fill their honey stomachs. That is an aid for you to see brood cells. The majority of the normal mantle of workers covering the brood to keep it warm seek open honey cells to fill their honey stomachs when they are smelling the smoke. It distracts the bees. It changes their behavior. If in fact you notice most of the bees filling their stomachs, it suggests you might be smoking too heavily.

Why this change in bee behavior? We speculate that through centuries of wildfires in the forest or green grasslands where they live, the smoke releases a fleeing response. The first manifestation of this is to fill up honey stomachs. Other forest animals flee smoke, some shepherding youngsters to flee with them, but only honey bees seem to initially delay by taking on food. Something we also see is bees, for example, prepare to leave a hive in their swarming behavior. No direct evidence, but that is why smoke works. A good theory, at least.

If you do not like to use a smoker, either for the bees or because the smoke might bother you, smelling up your clothes, causing breathing issues, are there alternatives? Yes, of course. You might purchase liquid smoke from a bee supply dealer. You spray it into the colony.

Or another alternative is to spray sugar water or regular, just plain water, as fine droplets onto the bees. Bees that get hit with a droplet of water or sugar water or this smoky, uh, mixture, uh, that you can purchase change their behavior. They self-groom or solicit a worker to groom. Adding a scent to the sugar water helps distinguish the hive and might speed up the grooming process.

Most beekeepers believe liquid smoke or spraying tiny droplets of water onto bees doesn't work as well to move bees and then that effect wears off more quickly. They are less likely to move the mantle of bees over that are over the brood.

Potential downside of the smoke odor, that is that liquid smoke, is that when sprayed into the hive, the odor may continue to persist after you've closed the colony. Sugar water or scented sugar water may induce robbing this time of year, for example, if there is a nectar dearth or poor foraging conditions exist.

Not using any tool, except the hive tool to free propolis when you open the colony is another option. You must move slowly when opening, being sure not to jar or create any high vibrations, and then nudging bees away from where your fingers are going to go as you grasp the frames. And listening to the bees. Are they continuing a normal hum versus an angrier buzzing sound?

That, uh, use of—non-use of a smoker or, uh, water droplets is okay for smaller colonies such as nucs or starter colonies. But this can lead to a rapid defensive response in larger, more populous colonies, especially if you drop a frame or bump the colony, or this time of year, when colonies are large and there's little for the workers to do. Going with this tool, that is the smoker, makes individual frame inspections uh easier. Going without, it is a riskier practice.

We should always practice smoker safety. Smokers get hot on the bottom and sides of that metal cylinder. Purchase a smoker that has a wire cage around it. It may save a nasty burn. Do not set the smoker down on any surface that might start a fire. Smokers often have a hanger, and you can hang it off the hive body where it will be close by.

Special preparations are needed during the dry season. Be extra cautious lighting the smoker. We recommend placing the smoker in a metal pail as you move from colony to colony, not on the ground. Uh, and as you close the colony, of course you're no longer going to be able to hang that smoker.

When emptying your smoker of fuel at the end of inspection, be sure the fuel is fully extinguished before leaving the apiary. It's a good idea to place your smoker in a closable airtight metal container. Many individuals look for those surplus empty uh munitions boxes from uh Army surplus stores.

Carry a fire extinguisher and keep it handy, especially now during the dry season. Other suggestions include to not use a smoker to inspect colonies on windy days during the dry season. Practice short open hive inspection periods. Clear all flammable vegetation at least 30 feet from around the hives.

In 2020, Oregon faced the worst series of fires in the state's history. This year seems to even be more damage to our forest. It seemed to come out of nowhere. It was nice on Labor Day, and then the smoke appeared. The skies turned the most foreboding shade of red. Thousands of people were evacuated from their homes. A number of apiaries were at risk of being consumed by the advancing flames. Some were lost, just as happened in earlier fires in California and Australia.

In the notes, I have a publication from Kathy Garvey of UC Davis, who summarized some of those earlier losses.

In the heavy smoke events, it was noticeable that the bees suddenly stopped flying. People wondered whether honey bee colonies were being choked by the smoke.

Fires move quickly, and an apiary can turn into a pile of ash, unfortunately, in a matter of minutes. Seeking to move colonies can put owners at risk of being caught in the fire zone. Colonies that may not burn can be singed. Just the heat alone can lead to colony death.

But even among surviving colonies, post-fire event, beekeepers often struggle to get their hives then ready for winter. Following a fire, conditions can be unsafe for beekeepers to work and properly manage their colonies. These preparations are particularly important since they are often the managements needed to help ensure better colony survival following that fire event.

OSU's Andony Melathopoulos has developed an extension leaflet that is probably the best and most complete information available on how wildfires affect—how the smoke from wildfires affects bees. I have this in the end notes with some others.

Few native bees nest in, uh, in forest areas. More grasslands, there are a lot more bees in—and deserts, uh, rather than humid—what humid areas actually have higher bee numbers.

Since most ground nesting bees construct their offspring chamber down uh four inches or more deep into the soil, they survive okay.

But above ground, twig and cavity nesting bees, bees such as in bee trees or beekeeper colonies—those populations are usually greatly reduced following the immediate season after a fire event. Small carpenter bee populations were reduced up to five years following this event that we described.

For one bright spot, native bee diversity and abundance uh typically increases in the years following a fire, as flowering plants predominate in a burn scar. Honey bees can benefit from this abundance if moved to burn sites as well. It has been postulated that fire likely played a major role in the landscape for our native bee fauna.

Our knowledge of what effects the smoke has on honey bees is limited. Many people observed something was wrong with the bees when the smoke rolls in. They certainly weren't visiting flowers like they were when it was clear. One reason for reduced flight is that smoke lowers the ambient temperature. Bees just aren't as active when it's cooler.

More critical, since bees use polarized light in the sky as their orientation compass to know where they're going, their guidepost to navigate from nest to flowers and back.

The problem with smoke is the patterns that are—that occur are not maintained when we get that heavy smoke cover. The pattern gets obscured, even distorted, once that heavy smoke haze sets in. The amount of polarized light in the sky can fall to levels below what a bee can discern.

But apparently this pattern gets obscured, even distorted, once that heavy smoke haze sets in. The amount of polarized light in the sky can fall to levels below what a bee can actually determine, discern. And apparently, even point bees in a different direction than normal. It's modifying that polarized pattern.

Getting to a flower gets to be a very hard task in smoke. Heavier the smoke, the more limited it's going to be.

It's been speculated that the ash itself may interfere with the ability of bees to breathe, smell, taste, as well as having other possible effects on their perception of their environment and their internal physiology. We do not find ash within honey bee trachea collected from that 2020 fire zone.

Tan and co-workers exposed butterflies to simulated smoke conditions. They too found no ash in the butterfly respiratory system. However, when examined in caterpillars, they found reduced survival and growth rate. They interpreted the results to mean that the ash isn't interfering with breathing as much as it's likely poisoning the larvae as they consume the toxic material contained in the ash coating leaves, um, and the branches that they consume.

Could pollen and maybe nectar, likewise, poison flower visitors post a fire passage? We simply don't know.

Let me leave you with 10 do's in summarizing smoke and fire safety.

One, practice smoker safety, lighting, handling lit smokers, and cleaning the spent fuel, and of course storage of the hot smokers as you leave the apiary. That is our job. That is a major fire safety.

Two, minimize inspection times when smoke events occur. Keep inspections under 12 minutes to reduce colony stress. Wildfire smoke alters pheromones, passage, and behavior of flight. Be aware.

3. Avoid unnecessary smoke stress. Do not open hives unless absolutely necessary during unhealthy air quality advisories, as foraging grinds to a halt. Hives already under pressure from, for example, this time of year from mites, lower food stores, etc., are at greater risk of decline.

4. Have evacuation preparedness. Establish an apiary evacuation plan. If you are near an active evacuation zone, fire zone, do not move hives unless instructed by a certified fire authority for your own safety.

Number five, defensible space. Maintaining cleared, low vegetation perimeters around bee yards and outbuildings minimizes fuel loads to protect colonies from external blazes. Plant flowering species that aid bees but do not add to the fire load. Oregon State University has a listing of such fire-resistant plants.

6. Supplemental feeding. Provide sugar syrup, pollen substitute if regional forage is burned or nectar intake plummets due to smoke haze. And during those periods of poor air quality.

Seven, provide clean water. Set out shallow water stations with pebbles or twigs so surviving pollinators can safely drink near unburned pockets, uncontaminated with ash.

Eight, as soon as feasible, document hive conditions before and after wildfire events for insurance, research, or recovery in your planning.

And for our native bee fauna, nine, uh post-fire nesting. Leave standing dead trees, what we call snags, and unburned pithy stems, where cavity and wood nesting native bees can rebuild.

And finally, ten, avoid immediate cleanup. Refrain from aggressive clearing of lightly scorched native flowering bushes, as local forage regrowth provides critical emergency food sources and a burn site that might quickly then rebound with more available flora for bees, native and our honey bees.

Hopefully, we will pass from the current wildfire smoke events. We certainly do not want to be the cause of a fire with careless smoker use. We do not want to create undue stress to our bees with inspections or excessive smoker use.

Until next time—next time, be well.