One of the significant pests threatening the beekeeping sector is an invasive species known as Aethina tumida. This organism quickly disrupts the internal balance of the hive, leading to serious economic losses. The management of this beetle, which causes honey spoilage and comb destruction in hives, is critically important for beekeepers. Protecting colony health depends on understanding this pest’s biology and implementing the correct control steps. Dealing with this situation requires proactive monitoring and integrated management strategies.
What is SHB? The Structure of the Adult Beetle
The small hive beetle (SHB) is a species known by the scientific name Aethina tumida, which infests honey bee colonies. Adults are dark-colored and have a hard shell. These beetles multiply rapidly inside the hive, damaging the comb, honey, and pollen. Recognizing this pest, which leads to the weakening of bee colonies, is the first step in control. Knowing its structure helps distinguish it from other organisms in the hive.
Morphology and Distinguishing Features from Similar Species
An adult Aethina tumida has an oval body shape. Its color is reddish-brown when young, turning black as it matures. Its length generally ranges from 5 mm to 7 mm. Its width is around 3 mm. These beetles have a hard exoskeleton (chitin). The head is distinct relative to the body, and its antennae are clubbed. This clubbed antenna structure helps distinguish them from other insects in the hive. They are different from some beetles that might look similar. For example, some saprophytic (decay-eating) beetles or harmless pollen beetles (Carpophilus species) that can be found in hives may be rounder or longer. However, the most defining characteristic of this invasive species is its ability to move quickly over the combs and in the dark corners of the hive. Bees have difficulty removing them. The flat shape of their bodies prevents bees from using their stingers effectively. Pollen beetles are generally slower and do not cause the same degree of aggressive comb destruction.
Flight Distance and Behavioral Patterns
The adult beetle is a capable flier. Its sense of smell is highly developed. It can detect the odors released by stressed or weakened bee colonies. It can travel long distances to find a new hive. Research shows that these beetles can fly quite long distances under favorable wind conditions. This situation causes the pest to spread rapidly between apiaries. Once inside the hive, they generally prefer dark and narrow spaces. They hide on the edges of frames, on the hive floor, or under the inner cover. They conceal themselves in cracks that bees cannot reach. This behavior makes them difficult to detect and difficult for bees to eject. In strong colonies, worker bees may trap these beetles in certain corners of the hive and cover them with propolis.
The SHB Life Cycle
This pest’s life cycle consists of four stages: egg, larva, pupa, and adult. This cycle begins inside the hive and completes in the soil. The speed of development varies greatly depending on environmental factors such as temperature and humidity. Understanding this cycle provides knowledge of when and where the pest is most vulnerable. Control strategies are planned according to these stages of the cycle.
Development Times from Egg to Larva
An adult female beetle can lay hundreds of eggs during her life. Sometimes this number exceeds a thousand. She usually lays her eggs in clusters in comb cells, pollen stores, or cracks inside the hive. The eggs are whitish in color and quite small, about 1.5 mm long. Under suitable temperature conditions (generally around 30°C), the eggs hatch in 2 to 4 days. The emerging larvae are the most destructive stage in the hive. The larvae begin feeding immediately. They consume honey, pollen, and bee brood. Larvae are cream-white and have distinct spine-like projections on their bodies. These projections distinguish them from bee larvae, which have smooth skin. Larvae move in groups within the hive, exhibiting “schooling” behavior. These larvae feed for 10 to 16 days until they reach about 10 mm in length.
Soil Preferences and Depth During the Pupa Stage
Once the larvae have grown sufficiently, they leave the hive to pupate. These larvae, often referred to as the “wandering larva” stage, typically exit the hive entrance or bottom ventilation at night and head for the soil. They prefer soft, moist, and loose-structured soils to pupate. Sandy and loamy soils are ideal for their development. They choose soil near the hive (usually within a 100 cm radius) that receives sunlight. Larvae burrow into the soil to a depth of 1 cm to 20 cm. This depth depends on the soil structure and moisture content. Their success in pupating decreases in very hard or clay soils. Therefore, the structure of the apiary ground plays a role in the pest’s spread.
The Effect of Soil/Moisture Conditions on Pupa Success
The pupa stage is one of the most sensitive phases in the small hive beetle’s life cycle. The moisture content of the soil directly affects the survival success of the pupae. Very dry soil causes the pupae to desiccate. Excessively wet or flooded soils lead to their drowning. The ideal moisture content is between 10% and 20%. Soil temperature is also important. Development stops below 10°C. The pupa stage generally lasts 3 to 4 weeks, but this period can extend up to 60 days depending on conditions. Adult beetles emerge from the soil and begin searching for new hives. Adults emerging from the ground immediately head towards hives or seek out a new apiary. This cycle allows the pest to constantly renew its population.
Damage Caused by SHB
An Aethina tumida infestation has devastating effects on bee colonies. The feeding activities of the larvae spoil the quality of the honey and cause the combs to melt. The bad odor spreading in the hive and the resulting fermentation can lead bees to abandon the hive. This situation causes serious economic losses and colony losses. The damage is not limited to honey; it affects the entire colony structure.
Honey Fermentation / “Sour Orange” Odor
The most obvious damage by larvae is seen on the honey. As larvae consume honey, they also defecate. This defecation introduces specific yeasts (Kodamaea ohmeri) into the honey. These yeasts begin to ferment the sugar in the honey. The fermenting honey foams, becomes watery, and can flow out of the hive. The smell that arises during this process is often described as the “rotting sour orange” odor. The honey loses all its commercial value. This fermentation can occur even at low moisture levels (e.g., below 18%) that normally prevent honey from spoiling. The presence of larvae completely changes the chemical structure of the honey. This can also happen rapidly in stored combs or combs left in the extraction room.
Colony Collapse and Economic Impacts
If the larval infestation cannot be controlled, the combs can completely melt. The mass of larvae creates a “slime” as it moves through the combs. This situation prevents bees from moving on the combs. Bee brood dies, and the overall hygiene of the hive deteriorates. Even a strong colony weakens in the face of a heavy infestation. Stressed worker bees and the queen bee may show a tendency to abscond (abandon the hive). This means the complete loss of the colony for the beekeeper. The economic impact is not just the loss of honey, but also the loss of the colony and equipment damage. The leakage of a fermented honey can cause wooden hive components to rot. Contaminated combs and frames become unusable, which may require the destruction of at least 5-10 frames.
Prevention Methods for SHB
The most effective method in combating this invasive species is to prevent the pest from entering the apiary. This is achieved through preventative care and good beekeeping practices. Sourcing bees and equipment from reliable suppliers, paying attention to apiary cleanliness, and always keeping colonies strong are the cornerstones of preventing an infestation. Taking precautions is always easier and less costly than treatment.
Certified Colony/Equipment Purchasing and Entry Controls
Buying new bee colonies or second-hand equipment is one of the most common ways the pest is transported to an apiary. When purchasing bees, certified breeders who document that they are free of diseases and pests should be preferred. All types of hives, frames, or beekeeping tools coming from outside sources must be thoroughly inspected before being introduced into the apiary. Equipment from other regions poses a significant risk. In suspicious cases, equipment should be frozen (e.g., kept at -12°C for at least 24 hours) or properly sterilized. New colonies should be kept in a quarantine area for a period and monitored for the presence of beetles before being integrated into the main apiary.
Apiary Hygiene, Equipment Sanitation, and Storage
Keeping the apiary surroundings clean and tidy is important. Old, unused hives or combs should not be left lying around. Such materials create a breeding ground for beetles. Comb scraps or beeswax residues that appear after honey extraction must be cleaned up immediately. Protective measures taken for wax moths are also beneficial for this species. Stored combs should be kept in a cool, dry environment. Beetle development stops if the temperature is below 4°C or above 45°C. Combs from dead colonies or extraction residues should never be left exposed in the apiary. These materials should either be burned or sealed in waterproof containers and disposed of quickly. The cleanliness of honey extraction rooms is also critical. Spilled honey or wax residues can attract beetles. Extraction rooms should be isolated so that bees and beetles cannot enter.
Strengthening Weak Colonies and Stock Management
The small hive beetle usually targets weak or stressed colonies. A strong and populous bee population can control the adult beetles that enter the hive. The bees trap the beetles in the corners of the hive (propolize them) or eject them. The beekeeper must prevent their colonies from weakening. They should monitor queen bee performance and, if necessary, combine or reinforce colonies. Reducing empty space inside the hive (narrowing) also makes it easier for the bees to defend. Keeping excess combs in the hive that are not covered by bees provides the pest with space to hide and reproduce. Colonies with less than 5 frames of strength are particularly at high risk.
SHB Control/Monitoring in Hives
Early detection of Aethina tumida is vital for successful control. Regular monitoring in the hive helps to understand the extent of the infestation. The use of bottom boards, placement of special traps, and seasonal checks are effective methods that help the beekeeper keep the situation under control. Monitoring indicates when intervention is necessary.
Monitoring Steps with Bottom Boards/Inserts
Sticky or oiled inserts placed on the hive bottom are a simple way to detect the presence of beetles. However, a more commonly used method is corrugated plastic boards placed as drawers under ventilated bottoms. Adult beetles fall to the bottom while moving around the hive or when disturbed by bees. The beekeeper can check these boards at specific intervals (e.g., once a week) to see the number of fallen beetles. This method gives an idea of the beetle population. If more than 5 adult beetles are seen on a board, this may indicate the need for intervention. Regular cleaning of the boards also prevents the beetles from pupating there.
Trap Placement and Inspection Frequency
Various in-hive traps developed for this pest are available on the market. These traps are usually placed between two frames or on the hive bottom. Their working principle involves containing a bait (vinegar, honey mixture, etc.) or oil (mineral oil) to attract the beetles. The beetles enter the trap but cannot get out and drown in the oil. These traps have holes small enough (usually 2.5 mm to 3 mm) for beetles to fit but bees cannot enter. In areas suspected of infestation, traps should be kept in the hive continuously from spring to autumn. They should generally be checked and cleaned every 2 weeks, and the attractant or oil inside should be replenished. Some traps are disposable and are discarded when full.
Seasonal Inspection Schedule and Record Keeping
Aethina tumida activity generally increases during the warm months, especially from mid-summer to early autumn. Early spring and late autumn are periods when colonies are weak and vulnerable to infestation. During routine inspections, the beekeeper should look not only at the health of the bees but also for signs of SHB. The underside of the inner cover, frame shoulders, and hive corners should be examined carefully. The number of beetles seen, the presence of larvae, and signs of honey spoilage (sour smell) should be noted. Keeping regular records makes it easier to track the course of the infestation and determine the time for intervention. For example, notes kept such as, “Mid-season check: Hive 3, 10+ adult beetles seen, no larvae” provide valuable data.
Methods of Combating SHB
Combating the small hive beetle requires an integrated approach both inside the hive and in the apiary surroundings. Soil applications target the pupa stage, while in-hive traps control adult beetles and larvae. In all methods, strategies that do not risk honey safety and do not leave residues should be preferred. Success depends not on a single method, but on the combination of multiple methods.
Soil Applications Around the Apiary
Since the pupa stage of the life cycle occurs in the soil, treating the soil around the apiary is an important control method. Registered soil insecticides can be applied to the soil around the hives (especially in the 100 cm to 200 cm area) to kill the pupae. Certain approved active ingredients are used for this purpose. The application is usually done in late summer or early autumn when larvae enter the soil, at a time when the soil is moist after rain. Extreme care must be taken to ensure these chemicals do not come into direct contact with bees or contaminate water sources. The application should only be made directly under the hives and should not be spread over large areas. This method can reduce the pupa population by 90%.
Non-Chemical In-Hive Trap Strategies
Avoiding the use of chemicals inside the hive is important to protect the purity of the honey. Non-chemical traps are therefore the preferred choice. These traps generally work on mechanical or physical principles. For example, corrugated plastic traps utilize the beetles’ hiding behavior. Bees trap the beetles hiding in these corrugations. Bottom traps containing mineral oil or vegetable oil capture and drown the beetles. Additionally, some traps containing natural substances like diatomaceous earth cause the beetles’ exoskeletons to scratch, leading to water loss and death. Another method is to use fine-mesh screens (screened bottom boards) placed on the hive bottom. These bottoms allow beetles and larvae to fall through but prevent bees from passing. The fallen beetles can be collected in an oil tray below.
Management of Residue Risk and Honey Safety
Every chemical substance used in control carries the risk of leaving residues in honey. Therefore, it is mandatory to strictly follow the label instructions of pesticides (insecticides) used in beekeeping. Chemical applications must be strictly avoided, especially during honey flow periods. Even when making soil applications, it must be ensured that the treatment does not contaminate hives or water sources. Chemical treatments in strip or tablet form placed in the hive must be removed a certain time before the honey harvest (e.g., at least 4 weeks). The preferred control methods should be chosen to protect the natural structure of honey and human health. Integrated Pest Management (IPM) principles should be adopted.
SHB Regulations
Because Aethina tumida is an invasive and rapidly spreading pest, it is subject to serious legal regulations in many countries. These regulations cover what must be done if the pest is detected, notification requirements, and quarantine measures to prevent its spread. Beekeepers’ compliance with these rules is mandatory for both their own operations and regional beekeeping. Legal responsibilities play a key role in slowing the spread of the pest.
Mandatory Reporting and Notification Process
Aethina tumida is recognized worldwide as a “notifiable” bee pest. A beekeeper who suspects or confirms the presence of this beetle in their apiary is obligated to report the situation to local agricultural and animal authorities without delay. The notification process is critical to stopping the pest’s spread. Early warning systems allow authorities to act quickly. Failure to report can lead to legal sanctions and the pest spreading to wider areas. Generally, notification is required within 24 to 48 hours of the first suspicion. Authorities will take samples to officially confirm the pest’s presence.
Quarantine and Destruction Protocols
Apiaries where the pest is officially confirmed and a specific area around them (e.g., a very large region, such as a 300,000 cm radius) are generally placed under quarantine. The removal of bee colonies, queen bees, hives, or any beekeeping equipment from this area is prohibited. This restriction aims to prevent the geographical spread of the pest. In cases of severe infestation or in regions where the pest has newly entered, authorities may decide to destroy the infested colonies. Destruction protocols include methods to ensure the complete elimination of beetles and larvae. These methods may include killing the colonies with sulfur or a similar method, followed by burning the hive materials or deep burial (at least 100 cm).
