Honey Bee Disorders: Non-infectious Diseases and Pests
- Queenlessness and Laying Workers
- Overheated Bees
- Chilled Brood
- Spotty Brood
- Wax Moths
Queenlessness can occur in many ways, but once a colony becomes queenless the reaction of the colony is predictable. The colony will become agitated and most of the activities of the hive are disrupted. When the beekeeper opens the hive, many bees will fan, much like when you see scenting bees (secretion of Nasonov pheromone and its dispersion by wing fanning). There may also be a loud roar from the bees. Usually within a few hours of being queenless, the bees will begin to construct emergency queen cells from existing cells containing worker larvae less than four days old. Nurse bees will supply the cell with large amounts of royal jelly to divert the development of the worker larva into a queen.
Usually the queen cell is constructed in time to permit requeening. If not, the colony becomes hopelessly queenless and will eventually die unless if a new queen is added to rejuvenate the colony. During the time between queenlessness and complete colony collapse, workers will begin to lay eggs inside the cells. At first glance one would think there is a queen in the colony, but with a closer look, it is obviously laying workers. Workers have the ability to lay unfertilized eggs when their ovaries are stimulated. Worker ovary development is normally suppressed by the queen's presence, but if the queen is killed or if she is old and not producing adequate amounts of pheromone then the workers begin to produce queen cells or lay eggs. Differences between worker and queen eggs are undetectable to the naked eye. Laying workers are usually revealed by the manner in which they deposit their eggs. A queen will lay a single egg cemented to the base of the cell in a cohesive pattern. A worker will lay numerous eggs in all areas of the cell and the pattern will be spotty.
One can discriminate worker-laid from queen-laid eggs by differences in the patterns of deposition. A queen will lay a single egg cemented to the base of the cell in a repeating pattern. In colonies with laying workers, the eggs are deposited in a disorderly manner, with one or more eggs per cell, sometimes persisting to the point of two larvae per cell, with many cells skipped altogether. This is the result of multiple competing laying workers, each vying for reproductive dominance and attempting to lay her eggs on top of a rival's. Re-queening a laying worker colony can be difficult because laying workers rarely accept a new queen. Vigilance by the beekeeper and prompt queen replacement are the solutions to this problem.
Starvation is one of the leading causes of colony collapse over winter; however, starvation can occur at any time. Colonies can perish from starvation if they go into the winter period with inadequate honey supplies or if the cluster becomes separated from the honey. Symptoms of starvation are numerous dead bees between the combs and on the floor, many positioned head first in a cell.
It is important to periodically check your colonies to ensure they have proper supplies of honey. Lifting colonies from the rear is a quick method for determining quantities of honey stores. If the colony is light, mix a heavy 2:1 (sugar:water) syrup and feed them with internal division board feeders, inverted plastic pails on top of the cluster or hive-top feeders. Do not rely on Boardman entrance feeders in cold weather since the bees are unable to leave the cluster in order to feed. Recommendations for food needs will vary by region, but for southern regions, a single hive colony will need at least one medium super of honey. That will equal a minimum of 60 pounds of honey or syrup.
Colony survival over winter is more likely if proper fall management strategies are followed. These include a strong viable queen, adequate supply of honey and pollen, colonies maintained in a disease-free condition, and well-constructed hives protected from extreme climatic conditions.
Bees may become overheated if they are confined in the hive during hot weather and have no access to water. It is especially a problem when hives are being moved in hot weather for pollination or to follow honey flows. Overheated bees crawl rapidly and flutter their wings. When released from their confinement they will disperse by crawling in a disorderly manner. When bees have died from overheating they are sometimes wet which is due to the bee regurgitating fluids in vain attempts to cool themselves. Temperatures exceeding 100 degrees F (38 degreesC) are usually the starting point for overheating. Overheating can be avoided by not confining bees during hot days for long periods. The best time to move bees is in the evening when it is comparatively cool. As long as bees are unencumbered by unnatural and temporary things like confinement, they are completely capable of regulating their nest temperature.
As ambient temperatures begin to drop, worker bees within the hive begin to form a winter cluster around the brood area. Their bodies act as both insulators and generators of heat. However, if the population of worker bees isn't large enough to encompass the entire region of brood, the brood may die from hypothermia. Chilled brood can also occur during spring build up. Sometimes the worker bee population has dropped over winter, and the queen lays more eggs than the worker bees can cover. Chilled brood are usually found at the edges or lower peripheries of the cluster. Instead of pearly white larvae, chilled brood will be yellowish white to brown with tinged black on the segmental margins. Sometimes the cappings of sealed brood that have died will be perforated. Chilled brood may resemble symptoms of EFB, but does not exhibit the characteristic ropy test.
Spotty brood can be a symptom of diseases like AFB or EFB or it can be a sign of a failing queen, queenlessness, varroa mites, or inbreeding. A good queen will lay eggs in a solid pattern so that brood of similar age will be contiguous and the resulting comb “solid” with brood (Fig. 6). A failing queen will lay eggs in a haphazard manner so that cells of varying stages will be interspersed together (Fig. 7). A failing queen may also lay drone brood (upright cells) interspersed with worker brood (Fig. 8). The solution for spotty brood is to check for disease or other disorders and re-queen as needed.
The greater wax moth (Galleria mellonella) is a natural scavenger of honey bee comb and its contents. Beeswax combs are vulnerable to wax moth damage (Fig. 9) anytime they are unprotected by bees - whether in a weak and declining colony or in storage as supers in a shed. When a beekeeper encounters a colony with wax moth damage, this is a sign that the colony was primarily weakened by a previous problem; wax moths are only a secondary scavenger. In nature, wax moths (Fig. 10) are valuable members of the ecosystem because they clean abandoned cavities of old comb (potentially contaminated with disease) and render it clean for the next occupying swarm. Many people outside of the beekeeping industry consider wax moths a beneficial insect because the larval stages are used as fish bait and for feeding insects in zoos.
Newly hatched larvae are white but successive instars are medium to dark gray on the top with creamy white undersides. The larval head capsule is brown. Wax moth larvae prefer dark combs because they contain a variety of nutrients such as entrapped pollen and larval skins. The larvae grow rapidly and will migrate toward the edges of the frames or corners of the supers to spin a cocoon and pupate.
Damage occurs as the larvae (Fig. 11) burrow into the comb feeding on the wax, larval skins, pollen and honey. As the larvae chew through the comb they spin a silk lined tunnel through the cell walls and over the face of the comb (Fig. 12). These silk threads can tether emerging bees by their abdomens to their cells and they die of starvation because they are unable to escape from their cell. This phenomenon is termed galleriasis. In severe infestations, the wax comb, wooden frames, and sides of the hive bodies can be heavily damaged (Fig. 13).
The most effective method for preventing wax moth damage in hives occupied by bees is to maintain strong colonies. The bees will remove the moth larvae and repair the damage as it occurs. Stored equipment can be protected against wax moths by fumigating it with paradichlorobenzene crystals or by stacking honey supers in a criss-cross fashion in open sheds. The penetrating air and daylight discourage colonization by moths. Some beekeepers store supers in enclosed barns with a lighted bug-zapper running constantly to kill emerging adult moths. This practice can eventually eradicate moths from the room.
Mice are the most common and troublesome rodent pest of honey bee colonies (Fig. 14 & 15). They become a problem during fall when the evening temperatures begin to drop. The beehives provide food (pollen, honey and bees) and protection from the cold. The mice destroy the frames and wax comb by chewing them to provide room to build their nest. Not only is the destruction of the equipment a problem, but the odor created by their urine and droppings can cause the bees to abandon a hive. These mammals can be kept out of colonies by reducing the size of the entrance as the weather begins to cool down. Mice also nest in stored bee equipment resulting in the same kind of damage; therefore care is also needed to keep these pests from stored equipment.
Bears (Fig. 16) are the most notorious of all the mammalian bee pests because they can literally wipe out an entire apiary in one night. However, your bear risks depend largely on where you live. In Georgia, bears are primarily a problem in the mountains and extreme southeast.
Bears enter a bee yard to feed on the honey and brood. Bears will usually only affect one to three colonies a night, but will continue to return until all the colonies in the apiary have been destroyed. Electric fences are one solution against a hungry bear (Fig. 17), but depending on his determination, nothing may deter him from getting to the hives and destroying them. Once a bear acquires a taste for honey, sometimes the best defense is just to move the colonies to another site.