Pests have always been an important factor affecting the success of honey bee colonies. Along with some that have been around as long as the bees themselves, there are several significant pests that have recently appeared in the United States that have not typically been an issue for our honey bees. From a beekeeper standpoint, pests are a constant risk that has to be managed to achieve any kind of success. Pests that are not properly managed can easily (and surprisingly quickly) cause the hive to leave in search of a better home.
Pests affecting honey bees can be divided into 2 groups: pests that cause damage inside the hive and pests that cause problems outside the hive.
The list of inside pests that affect honey bee hives includes:
- Tracheal Mites (acarapis woodi)
- Varroa Mites (varroa destructor)
- Wax Moths
- Small Hive Beetles
- Ants
- Mice
Tracheal Mites
Tracheal mites live and reproduce in the tracheal tubes of the honey bee. There are 2 species of these mites. One of these originates from Europe and the other is from Mexico. The existence of these 2 lines provides these mites with genetic diversity which adds to the challenge of controlling them.
The impact of tracheal mites is often underestimated and causes a great deal of harm to honey bees. (It is believed by some that tracheal mites have a greater negative impact on honey bee colony survival than varroa mites). An infestation of tracheal mites tends to be cyclical in nature and typically peaks in the winter. This is a time when bees are already in a stressful situation which enhances the negative impact that tracheal mites have on a colony.
Tracheal mites can become so severe that they completely block the tracheal tubes of the infected bees, shortening their life. As they reproduce, mites will lay eggs inside the tracheal tubes. These eggs will hatch in 14 days and newly hatched mites crawl out of the tubes and seek to attach themselves to young bees passing by. As they accomplish this, the cycle continues.
Symptoms that indicate that you have a problem with tracheal mites include: crawling bees that are unable to fly, K-wing deformity (the inter-locking wings become un-locked causing the K shape), and bees that fail to cluster during the winter time. All of these symptoms can have a devastating impact on the honey bees’ individual survival, and depending on the severity of the infestation, the survival of the entire hive. It is important to note that while these symptoms can be caused by other issues, the only way to truly diagnose tracheal mites is with more scientific means, therefore observations of these symptoms can be highly indicative of a tracheal mite infestation.
Varroa Mites
Varroa mites were officially diagnosed in the United States in the late 1980’s although it is widely believed that they were here much earlier. Varroa mites are now a wide spread nuisance existing on all continents with the exception of Australia.
Varroa mites spread rapidly in local populations as well as across large areas by several means. Migratory beekeepers obviously move them across large distances. They also spread quickly on a localized basis due to swarming, foraging worker bees, drifting between hives, and drone congregating areas.
The life cycle of these mites begins with a female mite entering a brood cell shortly before it is capped. Once the cell is capped, this varroa will attach itself to the developing larvae and begins to feed on the hemolymph of the developing honey bee. It is at this point that the female varroa begins laying eggs. The first egg to hatch is a male. Subsequent eggs hatch as females. These newly hatched varroa mites will mature and start to breed among themselves. Once the honeybee larvae matures and emerges, all of the matured female mites exit the cell with it to then attach themselves to other bees, continuing the cycle.
Varroa mites are naturally drawn to brood due to the methods of their reproductive cycle. They have a greater attraction to drone brood since drone brood stays capped for a longer period allowing greater reproductive success by the mites. Because of their affinity for brood, the appearance of mites on adult bees in any noticeable quantity is an indication of a severe infestation.
Varroa mites create an enormous amount of stress within a honey bee colony. Since they feed on the bees hemolymph, they cause weakness and stress which makes the bees much more susceptible to viruses. This is how they cause their greatest damage. Symptoms of a varroa mite infestation can be the appearance of severely deformed newborn bees as well as visually identifying the presence of these mites on either brood, adult bees, or both.
Wax Moths
There are two primary species of wax moths that can cause damage to honey bee colonies. They are the greater wax moth and the lesser wax moth. There are others but these are the 2 that cause the greatest damage.
Wax moths do not directly affect the honey bees themselves but they can cause tremendous physical damage within the hive. The wax moth’s ability to create havoc in a hive is related to the strength of the colony. A strong healthy hive has little trouble keeping this pest under control. Their biggest threat is to a weak colony. Without sufficient numbers of honey bees present to repel the moths, it is devastating.
Wax moths do their damage by laying eggs. These eggs hatch into larvae that consume the wax itself. As the larva migrate through the combs feeding they leave fecal contamination behind as well as a silk webbing. As larvae reach the cocoon stage, they will carve out indentations in the wood inside the hive. This damages the insides of the hive body as well as the structure of the frames themselves. A severe infestation not only results in large scale loss of wax and foundation but can literally destroy the wooden frames.
The two species of wax moths can be present at the same time. However, it is usually to the detriment of the lesser wax moth. The larvae of the greater wax moth will feed on the larvae of the lesser wax moth, reducing their numbers or even eliminating them all together. Neither of these species can survive freezing temperatures so they tend to be more of a problem in warmer seasons as well as in locations where it is above freezing year round. Their biggest threat during the winter can be to frames that are stored in heated buildings. Care must be taken to intervene or much of the wax in these frames will be destroyed.
Small Hive Beetles
The small hive beetle was first identified in the United States in 1998. By 2007, this pest was believed to be in every state. This beetle is native to South Africa and has had a tremendously negative impact on the European honey bees found in North America. It has been particularly bad in the Southeastern U.S. due to the climate and soils which allow it to proliferate rapidly.
The spread of the small hive beetle was assisted by migratory beekeepers as well as the sale of packaged bees. They have also been spread by the movement of used equipment where they gladly hitched a ride to new territory. Worse yet, this beetle has no problem flying for several miles as it seeks out a new home, using the smell and odor of beehives to help it navigate.
Infestations of small hive beetles can occur rapidly and overwhelm even strong colonies. Each female is capable of laying as many as 1000 eggs in her lifetime. Eggs are laid in cracks and crevasses in strong hives to avoid removal by worker bees. In weaker hives they can be deposited in open and un-guarded cells. One troublesome habit of small hive beetles is that they will create a small opening in capped brood and deposit their eggs inside the capped cell where it is safe from removal by the workers.
Adult beetles as well as their larvae will feed on pollen, honey, brood, and wax. As the larvae feed their way through the combs, they defecate in the honey causing it to ferment and liquify resulting in a thin gooey mess that runs out of the cells and even out the front of the hive. As the larvae mature, they exit the hive to pupate in the surrounding soil. However, if the soil directly surrounding the hive is not acceptable, they can and will move great distances out from the hive to find a suitable soil to finish their growth cycle. Their first preference is sandy soil. The presence of sandy soils in the Southeast and along the East Coast has contributed to their success in these areas.
A significant management challenge with the small hive beetle is the European honey bee’s lack of skill in dealing with this pest in hive. The beetle has hard outer shell that defends against the jaws and stings of the bees. Honey bees will corral this pest into corners and surround them in a propolis “jail” but this does not eliminate them as a problem. Worker bees have even been witnessed feeding these beetles. Another challenge with the small hive beetle is their ability to hide within the cluster during the winter time to survive. Not only do the bees keep them warm, the beetles have access to a food supply as they move with the cluster.
The small hive beetle has also proven itself as a significant pest in the honey collection process. Supers that are stored for any length of time prior to being collected can be quickly overrun and contaminated with beetles. One method of dealing with this problem is to expose the supers to below freezing temperatures for a minimum of 24 hours. Temperatures in the low 20 degree F range will eliminate all phases of the small hive beetle.
Ants
Ants are a normal part of beekeeping. Their attraction to the hive has numerous contributing factors that include food and shelter. It is not unusual to find ants in a hive and generally they do not cause much of a problem. However, if an ant colony decides to move in entirely and make itself at home, they can become a serious nuisance. Strong colonies can generally keep ant populations under control. Weak hives obviously have a greater challenge in dealing with ants due to lower numbers. Either way, even a strong colony can become overwhelmed by ants if their populations become too high leading to the colony abandoning the hive.
Mice
Mice typically create a nuisance in a bee hive when they decide to nest there for the winter. Generally, a strong and active hive knows exactly how to deal with mice invading their space. However, as cold weather settles in and bees go into cluster, the door is open for mice to move in and build their nest for the season. Mice don’t eat bees, they do however chew up combs and foundation and create a significant mess while in residence. As indicated, they are generally moved out as warm weather approaches and the bees break cluster but if they spent the winter there, the damage is done. Prevention is the best policy.
The list of outside pests that affect honey bee hives includes:
- Bears
- Raccoons, Skunks, Opossums
- Wasp and hornets
- Birds
Bears
With the understanding that many readers live in an area where bears are not a problem, there are many locations with healthy populations of bears. Bears and bees don’t mix and if you do live in an area that has a bear population you can expect that at some point it is going to be a conflict. In spite of the many cartoon depictions of bears seeking out beehives for a dose of honey, these interactions do not go well for the bees.
Bears will absolutely destroy a beehive. They tear the hives open and break them apart primarily for the brood. They love it and will consume brood and honey leaving a sad pile of broken hive bodies and a colony of very angry honey bees. Entire bee yards can be compromised and even outright destroyed in a short amount of time. As mentioned before in reference to mice, prevention is the best policy. Anyone attempting to keep honey bees in an area with a known bear population should invest in some electric fencing to deter them from seeking a snack in your bee yard.
Raccoons, Skunks, and Opossums
These critters as a group can be quite the nuisance to your honey bees. They are opportunists that will not pass up a quick meal at the expense of one or more of your beehives.
Raccoons are crafty creatures who are intelligent enough to take advantage of an easy meal. They can and will remove the hive cover to access they brood and honey inside. Care should be take to keep covers secure to prevent this from happening.
Opossums and skunks are natural predators and opportunistic feeders. They will readily consume dead bees and detritus around your hives making it critical to keep hygiene levels high. Keeping a clean bee yard will also reduce the smells that might attract bears so it is worth the effort. Opossums and skunks will also scratch at the front of the hive and eat the guard bees that respond. Typical symptoms of these predators included scratched earth in front of the hive, odor is also a dead giveaway especially with skunks. An unpleasant side effect of these pests is the attitude of the bees. They become quite aggressive in response and sudden changes in hive personality should be noted and cause the beekeeper to investigate if these night time pests are causing it.
Wasp and Hornets
Both wasp and hornets will predate on honey bees. They are a particular problem with weaker hives and have a tendency to be worse in mid to late summer. Wasp like yellow jackets are meat eaters and weak colonies with fewer guard bees allow them to invade the hive and consume large amounts of brood.
Several species of hornets will eat honey bees. They generally will orientate their attack toward the front of the hive and either grab bees directly from the entrance or catch them in flight as the honey bees leave or arrive. Hornets have powerful mandibles that make short work of the much lighter and smaller honey bees.
Birds
In the US there are several bird species that are known bee-eaters. The scarlet tanager, the summer tanager, and purple martins are all known to eat bees. While they may not be major pests, they can consume many foraging bees during a day’s time. Their predation typically peaks during the season when these birds are rearing broods of their own.
As you can see, there is no shortage of pests creating challenges for honey bees. Each of these pests contributes their own level of complications to the beekeeper trying to maintain healthy hives. In future articles we will need to look at options to control these pests and allow our honey bee colonies to remain strong and productive.
