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The bee louse (braula fly) is a parasitic pest of honeybees. It is often found on the head of the bee in an infestation. This is because the pest feeds on honey as well as nectar from the mouth-parts of honeybees. Bee lice reproduce in the beehive. Their larvae burrow through honeycomb and can cause a lot of losses in both brood and stored honey. Avoiding such losses is important in beekeeping. Severe infestations by the bee louse cost you your beehive products and weaken the honeybee colony. This guide leads you through understanding infestations and as well as providing tips and advice for bee louse treatment.
About the Bee Louse
The bee louse is an insect of the fly family. It is not recognized as a true parasite of honeybees but nonetheless, it is found in honeybee colonies quite often. The Diptera family of the bee louse has two genera and seven species in it. Bee lice are unusual flies due to their winglessness. They are not mites or lice as many would think. A bee louse is very small. Its size is nearly the same as a Varroa mite.
Many beekeepers are in the habit of calling this parasite of honeybees by its other name, Braulidae. It is a name that comes from Braula Coeca, which is the first species to be discovered. This was in 1818 by a German zoologist called Christian Ludwig Nitzch. In the year 1986, an entomologist from America called David Grimaldi discovered the genus Megabraula. If you read more about this bee parasite, you might find it also referred to by the name Braula fly.
Global Distribution and Spread of the Bee Louse
Bee louse has spread throughout the world and is today found in all major beekeeping regions. These include Africa, America, Australia and Europe. Bee lice prefer to stay on the mouthparts of the queen bee in a honeybee colony. For this reason, it is believed that they entered the United States beekeeping arena due to queen importation. Further selling and giving away queen bees in the country has caused infestations with lice in many places.
Species of bee lice are believed to have a preference for different honeybee races. The common bee lice in Carniolan honeybee colonies and Middle Eastern bee races, do not infest colonies of Italian honeybees. Braulidae Coeca is widely known in beekeeping because it is the species of bee louse that is commonly encountered around the world.
Bee Louse Life-Cycle
The life cycle of bee lice moves through four stages. Adult lice lay eggs that hatch on honey cappings after 2-7 days depending on the temperature that the egg is exposed to in the beehive.
Larvae emerge from hatched eggs and tunnel under wax cappings in the beehive. They leave a narrow tunnel that trails along the upper surface of the wax capping. It shows as plant-like venation upon close examination. At the end of the bee louse larvae, trails are sac-like appearances that may be pupating bee lice. Larvae undergo 3 larval stages and then pupate after 7-11 days.
The pupa stage lasts between 1 to 3 days. Adults emerge from the puparium. Each adult bee louse that emerges from its puparium must find an adult honeybee to attach itself to. If it does not do so within a day or two, it dies due to starvation. The adult bee louse goes to the mouth section of the bee when the bee is being fed or feeding other bees.
Adult female bee lice mate soon after emerging from their puparium. They lay eggs in the beehive to continue the reproductive cycle. Bee lice can survive in the absence of honeybee brood, but cannot live without adult bees. They are believed to get through winter by hanging onto bees through the cold season and stop laying eggs. Once it gets warmer, the female adult bee lice start laying eggs again.
Bee Louse Activity in Beehives
Adult bee lice have a life cycle that is very closely connected with infesting a honeybee colony. They roam on the bodies of adult bees looking to feed on the mouth secretions of honeybees. Bee lice do not harm adult bees directly. They can however be a nuisance in some areas of the beehive.
The adult lice eat honey stored by bees in the beehive. When they can access royal jelly, bee lice show a preference for it over honey. These adult lice are very fast on their feet. They scramble for food when nurse bees are feeding the queen or honeybee brood. This can cause brood to be poorly fed when there are many bee lice in the beehive. It can also lead to poor feeding of the queen bee. The adult bees that result from such larvae are weak and may die quickly.
Queen bees that are poorly fed as a result of bee louse activity do not lay eggs poorly and the bee population in the colony falls.
Where they are present, bee lice are found in beehives and on flowers. They stay on the flower and wait to climb onto bees. This is their primary method of gaining entry into beehives. In the beehive, adult bee lice lay their eggs on the cappings of comb cells.
Symptoms of a Bee Louse Infestation
Identification of bee louse infestations in beekeeping relies on the examination of honeybees and the beehive. Early diagnosis of the problem in the beehive helps you put in place management measures. It also allows you to apply the best bee louse treatment option that fits in the budget of your beekeeping operation. Late diagnosis may need you to rush to control the infestation.
The effect of bee louse infestations is easy to miss at first. However, large infestations cause the honeybee colony to weaken. Various symptoms can be observed including:
1. Low Honeybee Population
You will notice that the population of honeybees in the colony has fallen. Signs of this include finding boxes without honeybees patrolling them and reduced activity at the beehive entrance. When examining the beehive, you will also notice fewer broods in the beehive depending on the season of the year. This lowered honeybee population is a result of various factors, including fewer eggs being laid and a reduced lifespan of adult honeybees.
2. Poorly Laying Queen
The queen bee in your honeybee colony is affected by infestations of bee lice. Nurse bees in the colony attend to the queen bee and feed her. When she is being fed, bee lice compete with her for royal jelly. This is in addition to the queen bee having to share available royal jelly with the brood in its early stages of feeding. In the event that resources are scarce or the queen cannot outdo the bee lice, she gets poorly fed. In the honeybee colony, a queen bee lays eggs prolifically. When she is not fed well, her laying abilities are impacted. In an infestation where the lice out-compete the queen bee, she starts laying fewer eggs.
3. Visual Recognition of Bee Lice
In some instances, beekeepers have been able to see the bee lice attached to bees. This is often when the infestation is severe. Experienced beekeepers might also have better recognition capabilities than beginner beekeepers. This is especially true when the experienced beekeeper has had to deal with a bee louse infestation previously. Beginner beekeepers may also recognize the louse if they are vigilant enough. The bee louse has nearly the same body size as a Varroa mite.
These symptoms are not reliable for the diagnosis of a bee louse infestation. However, they should point you to investigate for the presence of bee lice in your beehive. Examination of worker bees and the queen bee are needed. A sample of worker bees from the colony suspected to have a bee louse infestation is examined since it would be too time-consuming to examine all the bees in the beehive. The queen bee must be identified, caught and examined even if it is only a brief inspection of her mouthparts.
Diagnosis of a Bee Louse Infestation
Diagnosis of a bee louse infestation is done using visual inspection. The beekeeper looks out for the eggs, larvae and adult bee lice in the beehive. Areas of interest include the honeybees in the colony inhabiting the beehive at the time. The following observations can be used to arrive at a conclusion that you have a honeybee louse problem in a beehive:
1. Bee Louse Size
The size of bee lice varies from 1.6 mm to 3 mm. They have very reduced eyes just above their antennae. These eyes are present on the cuticle as pale spots surrounded by chitinous rings that are pigmented. This has led some descriptions of the bee louse to indicate that adult Braulidae has grooves on the head that hide the antennae. Each adult bee louse has 3 pairs of legs. This fact is important when differentiating them from mites that have 8 legs since they are arachnids.
Legs on the bee lice are short and quite robust. They are used for quick movements that are critical for the lice to compete for food with larvae and the queen bee. The fast legs also enable the lice to hide quickly in small spaces when bees attempt to hound them out of the beehive.
2. Physical Appearance of Bee Lice
Unlike most other species in the flies’ family, bee lice do not have any wings or halters. They are therefore unable to fly and rely on locomotion using their legs to move from one place in the beehive to another. For the transfer between beehives and flowers, the adult bee lice cling onto honeybees.
For visual recognition of the bee lice, look for small reddish-brown insects that look like lice or mites near the mouths of bees. Bee lice have a tarsus (skeleton) that is in 5 distinct segments. At the end of the tarsus, arrangement are some claw-like teeth. These teeth are a result of the bee lice living close to bees and adapting to clinging onto bee hairs. The thorax of the lice is usually about half the length of the head in all species.
3. Larvae Recognition
Larvae of bee lice are useful in the diagnosis of an infestation. In the suspected beehive, look out for very small maggot-like larvae with a posterior end that is flattened. The anterior end of the larvae is pointed. These larvae can be found tunneling through the wax comb. They feed on wax and pollen. Their tunneling activity often causes honey to leak out of cells. It can lead to the fermentation of the honey. In such a scenario, the honeybees that eat fermented honey might get honeybee dysentery.
Pupating larvae of bee lice are white or yellowish in color. They measure between 1.4 mm and 1.7 mm. They are 0.5 to 0.75 mm wide. The pupae mature in a puparium and then leave that as adults through a ptilinum. This is an eversible sack at the front of the pupated larvae head that can inflate. It bursts an exit that is circular in shape for the adult bee louse to emerge. Finding puparium that fit such a description in the beehive indicates an ongoing bee louse infestation.
3. Examination of Honeybees for Bee Louse Sighting
Examination of honeybees is important in the sighting of bee lice. The adult bees in the beehive should be sampled for examination. The queen bee must be examined if you have any reason to suspect a bee louse infestation in a honeybee colony. This is because the queen bee is a major target for bee lice.
On average, about 30 bee lice are to be found on the queen bee in an infestation. Researchers have sometimes found as many as 180 bee lice on one queen bee. This is in stark contrast to the 1-3 mites that are found on adult worker bees. It is possible to find that some worker bees have bee lice on them while others do not. If there is an infestation, you are sure to find bee lice on the queen bee.
5. Bee Louse Egg Structure and Morphology
The eggs of the Braulidae are very small. Spotting them is not reliable for the diagnosis of a bee louse infestation. The eggs are oval-shaped and white in color. They have 2 lateral flanges that are flat and extend parallel to each other toward the longer axis of the bee louse egg. On average, bee louse eggs measure 0.78 – 0.81 mm in length and 0.28 – 0.33 mm in width excluding the two flanges. If you include the flanges, the eggs measure about 0.84 x 0.42 mm.
These eggs are laid on the capping of honey cells. This allows the larvae that hatch from the egg to quickly access honey. The capping of honey cells is thin wax that the larvae can easily burrow through. Its burrowing activity is assisted by having a pointed anterior and a flattened posterior. The trail left by the larvae is visible on wax comb. Adult bee lice lay eggs on many surfaces in the beehive but only the eggs laid on honey cappings hatch.
Bee Louse Treatment
Infestations of bee lice have been thought to have little or no effect on honeybee colonies. Indeed, this has been the case until recent times. However, it is now known that weakened colonies from existing infestations of bee lice leave the colony susceptible to opportunistic diseases, pests and parasites.
Various treatments are available to beekeepers aiming to control bee louse infestations. Some of the treatments reduce the population of bee lice while others have the capability to rid the beehive of all of them. The available treatment methods include:
1. Uncapping Honey When Harvesting
The normal beekeeping practice of uncapping honeycombs when extracting honey is often enough to keep the larval stage of bee lice in check.
2. Freezing Honey Comb
Further control measures targeting the larval stage of bee lice include freezing. It requires freezing the frames with honeycomb on them for at least 48 hours. This is usually adequate freezing time to kill the larvae, eggs, pupae and adults of bee lice that may be on the honeycomb. Freezing for 48 hours also kills many other pests of honeybees that are found in beehives such as small hive beetles and wax moths in various stages of their life cycles.
If you have many beehives to work on, you may cycle the frames from the beehives through your freezer to make sure you freeze all the frames at least once. When doing this, make sure to freeze all the frames from a single beehive at the same time. It avoids having frames that have undergone freezing and those that are yet to be frozen in the same beehive.
3. Application of Varroa Mite Control Treatments
Varroa control measures and products have been found to have an effect on Braula flies. Indeed, bee lice are often found in beehives where treatments for Varroa mite control have not been used in the recent past. Some treatments against Varroa mites may keep killing bee lice long after their concentration levels in the beehive have dropped below the threshold for killing Varroa mites.
The Varroa mite control methods that you can use to manage bee lice include but are not limited to:
Sugar can be used to actively reduce the number of Varroa mites in the beehive. It can be used with bee lice as well. In the procedure, powdered sugar is shaken onto bees in the beehive. You may do this in each beehive box, or once in the uppermost beehive box. Sugar powder on their bodies triggers bees to start grooming each other and themselves. In the process of grooming, the honeybees brush off Varroa mites from their bodies. The same happens when the procedure is carried out to control bee lice.
In control of Varroa mites, Fluvalinate is one of the chemical substances that are very popular. It is applied using varying delivery methods in beehives. Strips and sprays are the most effective, efficient and cost-friendly options that beekeepers use. Fluvalinate has been found to have an effect on bee lice too. It kills them when applied in concentrations suitable for the killing of Varroa mites. Indeed, the application of Fluvalinate kills up to 90% of the adult bee louse population in a beehive.
Essential oils that are effective against Varroa mites are also lethal to bee lice. These essential oils are mint and thyme. They are effective when applied in their pure form. These essential oils can be used in the beehive with honey super boxes on them. Another essential oil you can explore is wintergreen oil in a blend with mineral oil.
The use of oxalic acid is popular in Varroa mite control. It is easy to apply and effective against Varroa mites.
This is a surveillance procedure for Varroa mites that can be used on bee lice. In the procedure, you are able to see the bee lice on a screen that traps them. This is a lethal procedure for the bees that are used in it. You should make sure that the queen bee of your honeybee colony is not in the sample of bees you take from the beehive to perform this procedure.
Caution with Chemical Treatments
Beekeepers using Varroa mite control methods to manage infestations of bee lice should follow the application instructions carefully and follow them to the letter. Over-application of chemical and natural treatments can result in the poisoning of the honeybee colony. It can also cause more of the treatment to persist in the beehive thus lowering the quality of your beehive products.
Bee louse infestations in beekeeping are good for neither the beekeeper nor the honeybee colony that is infested. It is important to control the parasites, and where possible do away with their presence in the beehive. In a strong honeybee colony, the parasites live alongside bees without a lot of obvious signs. You will not know they are there unless you inspect your honeybees closely. The infestation weakens the honeybee gradually and can leave the bees susceptible to pests, parasites, and diseases of honeybees.
Bee louse treatment is easy to carry out for both beginner and experienced beekeepers. You should do it using both preventive and active measures if you find a beehive has been infested.
Have you had issues with bee louse in your beehives? Leave a comment below and let us know what your experience was like.