Small Hive Beetles
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Varroa mites, tracheal mites, disease, and hungry bears aren’t the only pests waiting for an opportunity to destroy unsuspecting honeybee colonies. The tiny Aethina tumida, AKA the small hive beetle, while not nearly as large as a bear, is one pest that can bring total destruction to a colony within days of arrival. The good news is keeping a colony safe from small hive beetles is much easier than protecting it from a hungry bear with the use of good management practices.
Infesting the hive
The small hive beetle (SHB) was first identified in the U.S. during the late 1990s and has spread to bee yards in every state except Alaska. Measuring a mere ¼ inch in length, these small brown to black beetles are capable of flying several miles to unsuspecting apiaries, often traveling in the midst of a honeybee swarm.
Odors emitted by each colony alert the beetles to weak hives, such as colonies with an old queen, queenless colonies, or colonies with too few members to protect the comb and brood from invasion. If no weakened colonies can be found, the SHB will move into a strong colony instead, where each beetle waits patiently for the opportunity to continue its mission of reproduction.
SHB Damage
While small hive beetles have four life stages — egg, larva, pupa, adult — it’s the larval stage that causes the damage within the colony. Females lay clusters of eggs throughout the hive in dark spaces, such as those found on the edges of frames and in unprotected comb. Eggs may also be deposited through holes made in capped brood when a colony is too weak to cover the entire brood nest; eggs hatch 24 to 48 hours after being laid.
Once emerged, larvae tunnel throughout the comb, feeding on honey, pollen, and even bee brood for seven days depositing the yeast Kodamaea ohmeri along their path. This tunneling damages the comb as the larvae move about feeding, and the yeast the larvae deposit quickly begins fermenting the pollen and honey, leading to a ‘slimed out’ colony. Once slimed, the honey is lost, most comb is too damaged for the bees to repair, and any remaining bees — if there are any — often abscond in favor of a more suitable home.
This sliming of the colony is often so severe that the devastation is evident before the beekeeper pops the lid. Slimed colonies emit a horrid, rotten fruit smell that can be detected several feet from the colony. If loads of honey were also in the hive during the infestation, honey from damaged combs would be noted running out the entrance or through the screened bottom board. Bees may or may not still be present once the beekeeper makes the discovery. The death of an infested colony — from first adult infestation to total destruction — can take place in less than a week in already weakened colonies.
Prevention
As with most things in life, prevention is preferable to corrective actions. As such, the best preventative practice any beekeeper in any region can do to protect their colonies from small hive beetle damage is to maintain strong colonies throughout the apiary. A strong colony is one that contains a young queen, sufficient food stores, and a sufficient population of bees to cover and protect the honey and brood frames within the hive.
These strong colonies force adult beetles that manage to find their way inside the hive to hide inside dark nooks and crannies to avoid harassment from house bees. House bees typically entrap these beetles in their own hiding places by covering the openings with propolis and by allocating guards to watch over the prisoners. These trapped beetles are not a threat in most regions, provided colony strength is maintained throughout the beetle’s reproductive season. Beekeepers then have the distinct satisfaction of crunching any escaped beetles under a hive tool each time the lid is opened.
However, while colony strength is the most effective tool for protecting colonies from beetles, there are other tools a beekeeper has at his disposal, each with varying amounts of success.
Treatment Options
Checkmite (coumaphos) is the only legally registered chemical treatment option approved for use within the hive for small hive beetles. Originally designed for varroa mites, this treatment is successful in treating small hive beetles, especially when the infestation is caught very early. However, as with many treatments used in the apiary, coumaphos readily penetrates beeswax and remains in the wax for extended periods. Coumaphos is also known to disrupt the queen’s egg production, thus further reducing the much-needed bee population within the affected colony, making the judicious use of this treatment a necessity.
Fipronil, or roach bait, is another chemical treatment many beekeepers utilize in many regions for SHB. However, fipronil is not approved for use in the U.S. for SHB and is also highly toxic to honeybees. Many stories circulate around bee events of the devastation caused by the illegal use of fipronil, with many ending in entire apiaries dying not from SHB, but from illegally administered fipronil instead. Too many other options exist to bother with the risks of fipronil, so be sure to skip experimenting with this one.
Beetle traps are a primary tool many beekeepers use, mainly where large numbers of colonies are not an issue. Some of these traps are modified bottom boards containing a bottom tray loaded with soapy/detergent water to trap and drown beetles as they fall to the bottom board. Others use compartmented traps hung between frames that contain a beetle lure, such as apple cider vinegar and oil used to drown attracted beetles.
Another type of trap is made from a sheet of material placed on top of frames to snag passing beetles. Bee catalogs offer versions of this preventative, while DIYers utilize the unscented Swiffer-style sheets. As beetles travel across the material, beetle feet become entangled in the fabric, where the beetle remains until a beekeeper removes the trap. The downside to these is many report bee trappings, making them unappealing to some.
While the larval stage is the destructive stage of SHB, a soil drench called Gardstar 40% EC is an outside-the-hive option that affects the pupal stage rather than the adult or larval stages. Using the neurotoxin permethrin as its active ingredient, this drench is applied to the soil several feet around each beehive during the SHB reproductive season (typically late spring through early fall). As larvae fall to the ground to dig into the soil for pupation, this neurotoxin kills the larvae. One treatment typically lasts for several weeks.
Biological controls such as nematodes and Bt. have been used successfully by many, while others still refute their efficacy. As with all things in beekeeping, experimentation is often the key to determining what works best in each environment.
The Honey Harvest
SHB are not only a threat inside the hive but also during the honey harvest. Because SHB larvae emerge within 48 hours of the eggs being laid, honey extraction and aftercare of honey frames must occur within 48 hours to prevent SHB larvae from destroying the harvest and the comb. Return wet comb to strong colonies for cleaning, removing unused but cleaned supers for winter storage. Cappings wax should also be rendered and cleaned or frozen before the 48 hours as beetle eggs are likely still present and incoming beetles happily land in uncapping tanks.
Freezing is the best option to store frames for the winter, as the cold temperatures kill any remaining eggs. However, storage is limited. An alternative is to wrap supers securely in several layers of trash bags and add Paramoth crystals to the enclosure. Replace spent crystals as needed throughout the season.
Small hive beetles can destroy a colony as effectively as a bear in a short period. However, with good management practices such as maintaining strong colonies and keeping a watchful eye, beekeepers can keep the devastation these tiny creatures cause to a minimum.
Originally published in the Winter 2022/2023 issue of Backyard Beekeeping and regularly vetted for accuracy.