When colony collapse disorder (CCD) hits a colony, the bees literally disappear. You open the hive, and no one is home. No dead bees. No signs of disease. Just nothingness. And its scale is shocking. Some commercial beekeepers have lost thousands of hives in the blink of an eye. The losses have been dramatic enough to create a crisis in agriculture, with fewer and fewer colonies available to pollinate crops.
The drama and mystery of CCD is juicy fodder for the media. While media attention is certainly deserved, and I wish it were sustained, there are other scourges affecting the viability of honeybees that no one outside the beekeeping community ever hears about. For backyard beekeepers, public enemy number one is the Varroa mite, not colony collapse disorder. If you have a colony of bees, you have Varroa mites, too. They are inescapable.
There are three basic approaches to dealing with Varroa mites. Pick one, try them all, or use them in combination, but don’t ignore the elephant in the room. These little buggers are small in size, but they loom large in a colony’s life.
Some beekeepers are putting natural selection to work through nonintervention. If you don’t treat a colony and it survives the mites for three years or longer, it has qualities that make it stronger than the colony that succumbs the first or second year. Those are the bees you want more of, not the ones you have to prop up artificially.
Your typical bee package from a large commercial supplier will not hold out against mites for long without intervention, but if you seek out people who are breeding survivor stock, you will have a better chance of success with this strategy. Survivor bees have a genetic trait called Varroa-sensitive hygiene, making workers more likely to identify and remove pupae infected with mites. There are also the options of raising Russian honeybees, a mite-resistant strain or using small-cell or foundationless frames.
Other ways to battle varroa mites
To help your bees battle Varroa mites, there are chemical-free weapons in the beekeeper’s arsenal.
Support nutritional health. You know that when your body is stressed, from poor eating habits, for example, you’re much more likely to get sick. Honey and pollen that bees forage from the land are the best food for them. Never take more honey from the hive than the bees need for themselves and assume that you can replace it with sugar syrup. Never feed them honey from the supermarket, which can actually introduce disease.
Dust with sugar. Giving your bees a bath of powdered sugar will dislodge many mites and send them falling through the screened bottom board.
Trap mites in drone comb. Mites reproduce most successfully within drone comb and have evolved to seek out the cells of drone brood first, before resorting to worker brood. Use this to your advantage by baiting mites into frames filled with drone pupae that you remove and freeze to kill your quarry.
Break the brood cycle. Mites depend on bee brood for their life cycle. If you keep your queen from laying, either by caging her for several weeks or by removing her and letting the bees raise a new queen, you have stopped not only the bees but also the mites from reproducing. This technique is effective for established colonies, not those in their first year.
Mites do not survive without bees as their hosts. When a colony dies from Varroa predation, the mites die also.
Chemical control is a touchy subject. People who use hard pesticides often think this is the only efficient and effective way to control Varroa mites. There are considerable downsides, however, including these:
• Because of extensive use, mites have developed resistance to the hard chemicals on the market. Using these chemicals as a preventive measure, rather than to treat a verifiably high level of infestation, is irresponsible and unsustainable.
• Long-term exposure compromises the health of the queen. Beeswax absorbs the chemicals, becoming permanently contaminated. Miticides in combination with other chemicals (either that you introduce or that the bees bring back to the hive from the landscape) may have unintended effects that compromise a colony’s health.
• Increasingly popular as an alternative are so-called soft chemicals, including thymol-based essential oils and formic acid pads or strips. Though these products don’t kill mites as forcefully as the hard chemicals, they are gentler on the bees, don’t pollute the wax, and are thought to be less likely to breed resistance. Nevertheless, no matter what commercially available treatment you use (if any), follow the directions exactly. Sloppy practices, such as leaving a treatment on the hive longer than the directions indicate, expose parasites to weakened chemicals that are below a verifiably lethal threshold. Those that survive the exposure are the ones with resistance to that chemical.
Sugar instead of miticide
A lot of us get into beekeeping because we want to have a positive impact on the environment and an enjoyable intersection with the natural world. Messing with chemicals that can burn your eyes, skin, or lungs if improperly handled probably didn’t fit your vision when you started. The good news is that you don’t have to use chemicals if you don’t want to. There are some Varroa controls as harmless as sugar and ice.
Birds are born with an instinct to take dust baths, which loosen mites that have burrowed through their feathers. Most honey bees do not yet have a genetic instinct to groom away Varroa mites since the parasite has been invading bee colonies only since 1987 and most beekeepers remediate chemically rather than breeding for hygienic traits. Taking the principle of this strategy from other animal species, some beekeepers coat bees with a dusting of powdered sugar. As the bees clean the sugar away, many mites drop off and fall through the screened bottom board. Here’s how to do it:
1. At each hive inspection, remove the supers (if you have any on top).
2. Sift confectioner’s sugar into the top hive body, making sure that sugar falls in between all of the frames. Use a half cup if there is only one deep or a full cup if there are two deeps.
3. Use a bee brush to sweep sugar off the top bars of the frames.
Sugar dusting removes only adult mites that are feeding on adult bees. Two-thirds of the mites are safely nestled inside brood cells and won’t be affected by the sugar dusting. A sticky-board mite count taken a week after your first dusting will show the same level of mites that you had before, but this is because new mites have hatched out. What the sticky-board count can’t show is that fewer adult females succeeded in moving into cells and laying eggs.
Mites prefer to lay eggs in drone cells. Drones take a few days longer than workers to hatch into bees once their cells are capped, which increases the reproductive success of mites threefold. We can use this knowledge to lure the mites into a trap.
The basis of the trap is a frame with drone-comb foundation, which looks much like other plastic foundation except that the cells are larger, signaling the queen to lay drone eggs there. Here’s how to do it:
1. Beginning in June or whenever the colony seems strong enough to sacrifice some brood-rearing energy, insert a drone-comb frame close to other brood frames within each deep. To make room you need to remove a regular frame. Choose one that has no or little brood.
2. Wait until the queen lays eggs and many of the cells are capped before removing the frames — three to four weeks. Timing is critical! If you don’t wait until the cells are capped, you can’t guarantee that there are mites inside, but if you wait too long and the mites hatch, you will have reared a bumper crop of parasites, which is worse than doing nothing at all.
3. Put the frames in plastic bags inside your freezer, which will kill the enemy and, sadly, the drones, too.
4. Before the next hive inspection, remove the frames and let them warm to room temperature. Break the cells open with a cappings scratcher and reinsert the frames into the deeps. Worker bees will haul the mortal remains out of the cells and start the cycle all over again. Tip: If you have a bird feeder, you can scrape the drone frame clean after freezing and the birds will eat those tasty grubs up!
5. Continue trapping monthly, but stop when brood rearing drops off for the season.
Sugar dusting and drone trapping are most effective when used in combination since each strategy on its own does not pack enough punch to manage Varroa adequately.
Guest post by Alethea Morrison of Grit