European Foulbrood (EFB): What is it And How is it Treated?

European foulbrood (EFB) is a bacterial brood disease that poses a significant challenge for beekeepers worldwide. The United Kingdom, in particular, has struggled to contain this disease, with EFB being the country's most widely spread bacterial brood disease. 

european foulbrood

European foulbrood

European foulbrood (EFB) is a bacterial brood disease that poses a significant challenge for beekeepers worldwide. The United Kingdom, in particular, has struggled to contain this disease, with EFB being the country's most widely spread bacterial brood disease. 

While EFB has yet to spread to New Zealand, it is present in eastern Australia. Without strong preventative measures, this disease is likely to continue spreading to other areas that have not been affected.

EFB primarily affects the brood, which is the bee's offspring. The bacteria responsible for EFB can penetrate the brood cell and infect the larvae, causing them to die. The bacteria can then produce spores that can survive in the environment for years, infecting new colonies and perpetuating the disease.

The effect it has on the hive

European foulbrood (EFB) is a bacterial brood disease caused by the Melissococcus pluton bacterium. This disease primarily affects the bee larvae and can cause a significant reduction in the hive's capacity. If left unchecked, EFB can lead to the death of the entire colony.

The larvae become infected with the bacterium when they consume contaminated food. The bacteria then multiply in the larvae's gut and produce toxins that can cause the larvae to die. The dead larvae turn brown and form a slimy mass, which is highly contagious and can spread to other larvae and colonies.

In addition to contaminated food, European foulbrood (EFB) can be transmitted through other means. One way that EFB can spread is through robbing. A colony that EFB weakens is more susceptible to robbing, which increases the likelihood of the infection spreading to other hives.

Beekeeping equipment can also be a source of EFB contamination if it is not adequately cleaned and disinfected. For instance, hive tools, smokers, and protective gear can be contaminated, spreading the infection to other colonies.

Transferring combs from infected hives to a previously uninfected hive can also transmit EFB. Beekeepers must ensure that they do not share equipment or combs from infected hives with uninfected ones without proper cleaning and disinfection.

Preventing the spread of EFB requires a comprehensive approach that includes practising good hygiene, regular inspections, and appropriate management strategies. Beekeepers must avoid robbing and ensure all equipment is thoroughly cleaned and disinfected. Additionally, beekeepers must carefully manage the transfer of combs between colonies to prevent the spread of the disease.

The larvae of a hive can become infected with a bacterium that grows within their gut. This bacterium consumes most of the food the larvae ingests, leading to starvation and death. 

However, if the larvae manage to survive the disease and undergo metamorphosis into a pupa, they will then excrete more of the bacterium through their faeces, perpetuating the spread of the infection within the hive. On the other hand, if the larvae succumb to the disease, they will dry out and turn into a dark scale, contributing to the infection's proliferation.

Hives are particularly vulnerable to infections when exposed to stressors such as relocation, unfavourable weather conditions, or inadequate nutrition. Even when the symptoms of a disease are not apparent, the bacterium can persist within the hive and reemerge if the hive experiences stress from external factors. It is essential to monitor hives and provide optimal conditions to reduce the risk of infections and their potential resurgence.

What to look for and how to detect

Early detection of European Foulbrood (EFB) can be challenging due to the behaviour of worker bees, who often remove diseased larvae. Some larvae may die before being capped, while others may die after capping, leading to misdiagnosis with American Foulbrood. To help identify EFB in their hives, beekeepers should be aware of the following symptoms:

  • A change in colour of the diseased larvae from white to a yellowish brown

  • Dead larvae that may have a watery consistency

  • The presence of a sour odour

  • An uneven brood pattern with a mixture of capped and uncapped cells.

It is essential for beekeepers to regularly monitor their hives and be aware of these symptoms to diagnose and treat EFB infections promptly.

As European Foulbrood (EFB) is most likely to occur in the spring or autumn seasons, it is recommended that beekeepers conduct a minimum of two thorough examinations of their hives annually during these times. To perform the examination, beekeepers should remove each frame, gently brush off the bees, and carefully inspect it for any of the symptoms listed above.

Preventative measures

The most effective way to protect hives from European Foulbrood (EFB) is to prevent infections from occurring in the first place. Although it is not possible to eliminate the risk, the following steps can significantly reduce it:

  • Maintaining high levels of hive hygiene by cleaning all beekeeping equipment and avoiding the introduction of unknown bees or equipment to the hive.

  • Replacing the queen bee with a young and healthy queen regularly. Ideally, breed from bees that have already been proven to be disease-resistant.

  • Taking precautions when moving bees to minimize stress, as stress is a significant risk factor for EFB.

  • Providing bees with access to ample supplies of pollen and nectar and using artificial feeding methods when necessary to maintain low-stress levels.

By implementing these measures, beekeepers can help protect their hives from EFB and ensure the health of their colonies.

Treatment and Control

European Foulbrood (EFB) can be treated with antibiotics. Still, the widespread use of antibiotics may result in the development of antibiotic-resistant strains of the bacterium. As a result, the most effective way to control the spread of the disease is to destroy affected colonies.

Suppose multiple colonies are present, and more than 10% display symptoms of EFB. In that case, it is recommended that every colony be treated. This approach helps to prevent the spread of the disease and ensure the health of the remaining colonies. It is essential to follow the guidance of a professional beekeeper or veterinarian when dealing with EFB to effectively manage the disease and minimize its impact on the hives.

If you suspect you have Foulbrood, contact your local Inspector.

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Oxalic Acid a Popular and Effective Treatment for Varroa Mite

Oxalic acid is a naturally occurring organic acid found in various plants and vegetables that are part of our daily diet, including honey. Its abundance in the environment means we are exposed to it regularly, and it is considered safe to consume at low levels.

varroa mite

Varro mite on a working bee

Oxalic acid is a naturally occurring organic acid found in various plants and vegetables that are part of our daily diet, including honey. Its abundance in the environment means we are exposed to it regularly, and it is considered safe to consume at low levels.


Oxalic acid has many applications outside of beekeeping. It is commonly used as a cleaning agent for surfaces such as buildings, swimming pools, and rust stains. It is also used for bleaching wood and as an ingredient in tooth-whitening products.

As beekeepers, we use oxalic acid as a "soft" acaricide to combat our primary pest, Varroa destructor. Oxalic acid is an effective treatment for varroa mites due to the way it interacts with them. Unlike some other treatments, it is unlikely that varroa mites will develop a resistance to oxalic acid. However, it is always advisable to rotate treatments as part of an integrated pest management strategy to avoid the overuse of any single treatment, including oxalic acid.

Treating the varroa mite is challenging because the mites take advantage of the honey bee's natural behaviour. Honey bees reproduce by swarming, and they may also rob from other colonies at certain times of the year and drift from hive to hive within an apiary. This means that any female varroa mites attached to adult honey bees will be transported to a new colony along with the bee, making it difficult to control the spread of the mites.

When beekeepers manipulate colonies, they can inadvertently move varroa mites between hives, especially when they move bees or broods. This can happen during swarm control, making nuclei or boosting other colonies with brood. Varroa mites are especially problematic during their reproductive phase, which occurs in sealed brood cells. Therefore, beekeepers need to take steps to prevent the spread of varroa mites, such as using treatments like oxalic acid and implementing integrated pest management strategies.


The varroa mite enters the reproductive phase when it moves into a brood cell after the dispersal phase. This typically occurs around day 5 of the honey bee egg hatching into a larva. The mite waits until the bees cap the cell before laying its first egg. This strategic move ensures its young are kept safe and well-fed. Each mature female lays around 5-6 eggs, with the first being male and the rest female. The females mature and become reproductive in just seven days. This reproductive phase of the mite's life cycle is particularly devastating as it can rapidly increase the mite population within a colony.

varroa in a hive frame cell

Varroa on a frame cell

As the varroa mite population grows under the brood cap, it can be difficult for beekeepers to access these mites. There are specific times of the year when varroa treatment has the most impact on the population. Winter is one of the best times to treat oxalic acid, which does not penetrate the brood cap. The colony is at its smallest, and there is little to no sealed brood around the winter equinox. The varroa population is also small when the colony is small, making it easier to manage. The oxalic acid will impact the varroa population when they are sapping the winter bees of their vital fat body tissues, which sustain them through the winter. Another ideal time to use oxalic acid is after a colony has swarmed. All the varroa mites taken by the hive will be on the bees in the dispersal phase, so an oxalic acid spray here will significantly impact all the mites.

Due to the close relationship between the varroa mite and its honey bee host, it is highly challenging to eliminate varroa from a hive. Furthermore, there is a constant risk of reinfestation from other hives with varroa, even if a colony has been treated and appears to have little to no mite infestation. Thus, beekeepers need to have a proactive approach to varroa management and implement integrated pest management strategies to maintain healthy colonies.

Like honey bees, varroa mites have a lifespan of 2-3 months during the active season and up to 5 months in the winter. In the winter, adult varroa mites live on the honey bee and primarily feed on the bee's fat body tissue, not the haemolymph as previously believed. Samuel Ramsey made this discovery in 2019, revealing that the varroa mite targets the honey bee's "liver," a crucial organ that performs essential functions. When choosing between fat body tissue and haemolymph, varroa mites prefer the former. They live longer and lay more eggs when they consume fat, which suggests that fat is an essential part of the varroa mite's diet.

Varroa mite infestation poses a significant challenge for beekeepers, and if left unmanaged, it can lead to colony collapse and death within 2-3 years. The risk of colony mortality increases with higher varroa infestations, underscoring the importance of treating varroa to avoid the risk of losing your colony over winter.

Treating varroa mites with oxalic acid

Oxalic acid is a potent killer of the varroa mite, a parasitic mite that infests honey bees. The acid works by crystallising on the adhesive lobes, the mite's feet, and its feeding mouthparts, penetrating the mite's body. The varroa mite's adhesive lobes contain a watery secretion that binds to the oxalic acid crystals, causing them to grow. This process causes severe damage to the mite's vital organs and eventually results in its death.

Winter Trickle Method

The winter trickle method is the most widely used method for treating varroa with oxalic acid. This involves mixing oxalic acid with sugar syrup and dribbling the mixture over the bees in the hive during winter when the colony is bloodless. The acid kills the mites, which are attached to the adult bees and hiding in the cracks and crevices of the hive.

Oxalic Acid Spray

Another popular way to apply oxalic acid is through a spray. This method treats varroa when the colony has a brood because the acid can penetrate the cells and kill the mites hiding there. To apply the spray, beekeepers mix oxalic acid with sugar syrup and spray it over the bees in the hive. It's important to note that the spray can only be used without honey supers to avoid contaminating the honey.

Vaporization Method

The vaporisation method is another way to use oxalic acid to treat varroa. This method involves heating oxalic acid crystals to produce a vapour, which is pumped into the hive. The vapour penetrates the cracks and crevices of the hive and kills the mites hiding there. This method is effective when the colony has a brood, but it requires specialised equipment and safety measures to prevent accidental exposure to the vapour.

Oxalic acid safety when applied to hives

Oxalic acid is an irritant; exposure to any solution or vapour can irritate the eyes and respiratory system. Always wearing protective clothing, including acid-resistant gloves, safety glasses, and a respiratory mask when vaporising, is essential to minimise the risk of inhalation. Additionally, always vaporise your hives with oxalic acid upwind to further reduce the risk of inhalation.

Oxalic acid proves to be a valuable asset in the arsenal of a beekeeper. It is an economical alternative that can easily be applied to the hive through spraying or trickling. Although the initial cost of oxalic acid vaporisation may be higher, it becomes more affordable if beekeepers pool their resources and share a vaporiser. Long-term usage favours vaporisation, especially if one has numerous hives to treat. Alternatively, a successful honey season could warrant the purchase of a new and exciting gadget.

The benefit of the colony's tolerance to oxalic acid is that it can be distributed throughout the hive, enabling the bees to counter mites efficiently. However, unlike formic acid, its effectiveness is limited as it cannot penetrate the brood cap. Thus, only phoretic mites are impacted. However, if oxalic acid is administered when the colony is bloodless, its efficacy is notably impressive.

Traditionally, oxalic acid is used in the winter, particularly during the Christmas season. However, employing oxalic acid in the spring or summer, particularly during swarming or when colonies experience a brood break, is another opportune time to administer this remedy. Incorporating oxalic acid into an Integrated Pest Management (IPM) strategy is an excellent approach to controlling the varroa population in hives.

It is important to note that using oxalic acid in beekeeping requires careful consideration and execution. Inappropriate usage could result in detrimental effects on the hive and its inhabitants. Therefore, beekeepers should equip themselves with comprehensive knowledge before treating.

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Homemade Organic Insecticide for Vegetables

Grow your own veggies and enjoy fresh produce with peace of mind! As we all know, pests can be a real problem in vegetable gardens. Thankfully you don't have to rely on harsh chemical-laden pesticides; there are several homemade organic options that can be made from simple items around the house—saving you money while keeping toxins at bay.

Grow your own veggies and enjoy fresh produce with peace of mind! As we all know, pests can be a real problem in vegetable gardens. Thankfully you don't have to rely on harsh chemical-laden pesticides; there are several homemade organic options that can be made from simple items around the house—saving you money while keeping toxins at bay.

Oil Spray

Do you have pesky sap-sucking insects like aphids, thrips, spider mites and whiteflies ruining your vegetable crops? Create a simple homemade oil spray with 1 tablespoon of dish soap and 1 cup of cooking oil from a fresh bottle. Mix the concentrated liquid with water using 4 teaspoons to every pint of water before application. For optimal shelf life, store the concentrate in an airtight glass jar in a dark, dry space until it’s time to use it! Once every 7 days liberally mist vegetables for full pest control.

Shampoo Spray

Baby shampoo is a great natural solution for controlling common garden pests including aphids, whiteflies, scale, thrips and spider mites. To make the baby shampoo pesticide spray just add two tablespoons of baby shampoo to one gallon of water in a spray bottle and thoroughly cover your plants with it. Let it sit on them for several hours before washing off gently with a hose. Remember not to use this mix under direct sunlight or when dealing with hairy-leaved or waxy vegetables such as squash!

Garlic Spray

Keep away unwanted pests from your vegetation with a natural pesticide that is odoriferous and easy to make! All you need is a blender, 10-12 garlic cloves, 1 quart of water, cheesecloth, and 1 cup of cooking oil. Blend the ingredients together before allowing them to sit overnight. Afterwards, strain it through a cheesecloth into an open glass jar for ultimate effectiveness. This concentrated brew can be kept for weeks until needed. If you want even more potency, add one tablespoon of cayenne pepper to the mixture and let it steep in the liquid for another day before filtering out any remaining solids. Make sure that when using this DIY pesticide, dilute 1/2 cup of the fluid with a gallon of water prior to application.

Pepper Spray

Red pepper powder is a multi-purpose ingredient that adds flavour and zest to culinary creations, but it can also be used as an effective homemade pesticide. To create this concoction, simply mix 1 tablespoon of red pepper powder with 6 drops of dish soap and one gallon of water until blended into a solution. Use a garden sprayer to thoroughly cover the vegetables with the mixture; if necessary, apply again once per week for maximum efficacy against pests such as leafhoppers, spittlebugs beetles and loopers.

A Word of Advice

Prior to spraying your entire vegetable plant, be sure to test any organic spray mixture you make on a single leaf. Do this the day before use in order to ensure it will not cause burning or damage to foliage. Furthermore, for best results and protection from potential burn injuries avoid treatment during hot midday hours - opt instead for either early morning or late afternoon applications. Some products composed of oils should never be applied when direct sunlight is present as they may scorch and harm plants otherwise.

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The US Government Approves the World's First Vaccine for Honey Bees

In a monumental achievement that may potentially help prevent the widespread devastation caused by honeybee disease, the US government has granted conditional approval for Dalan Animal Health's world-first vaccine. This innovative vaccine is set to give beekeepers an additional tool in their fight against American foulbrood - boosting hopes for mitigating the damage done to vital pollination colonies.

American foulbrood

In a monumental achievement that may potentially help prevent the widespread devastation caused by honeybee disease, the US government has granted conditional approval for Dalan Animal Health's world-first vaccine. This innovative vaccine is set to give beekeepers an additional tool in their fight against American foulbrood - boosting hopes for mitigating the damage done to vital pollination colonies.

Annette Kleiser, CEO of Dalan Animal Health, announced with enthusiasm that their new vaccine is set to revolutionize worldwide food production by protecting honeybees. "We are excited to offer a game-changing approach to how we care for insects," she said.

With the newly developed vaccine, commercial beekeepers can now protect their hives from the debilitating and fatal effects of foulbrood. Caused by Paenibacillus larvae bacteria, this disease has been found in as much as 25% of US hives, leaving little choice for those affected but to eradicate all infected colonies and medicate with antibiotics. The recent creation of a vaccine is an immense relief for beekeepers everywhere who are faced with combating this otherwise incurable affliction.

Keith Delaplane, an entomologist at the University of Georgia partnering with Dalan for vaccine development, noted that beekeepers could easily identify this condition as it reduces larvae to a brown gooey mess accompanied by its putrid smell.

By adding a portion of the bacteria to the royal jelly fed by worker bees to the queen, an immunological effect is produced on bee larvae as they hatch. This has been found through studies conducted by Dalan to reduce mortality rates from foulbrood significantly. Thus, this vaccine can be used effectively in honeybee colonies for protection against such diseases.

Delaplane explained that the ideal situation would be to feed queens a vaccine-fortified cocktail within their queen candy - an easily digestible substance provided to them while in transit. The selling point? A guarantee of “fully vaccinated queens” for beekeepers!

Originally hailing from the United States, American foulbrood has now spread across the globe. According to Dalan's research, this breakthrough could potentially be leveraged in order to develop vaccines for other bee-related diseases such as European foulbrood.

As honeybees have become industrialized, moved around and used to pollinate agricultural products, they are now subjected to a variety of illnesses that can decimate entire colonies. Beekeepers must provide significant interventions in order for the population of hives to remain stable. The US is heavily reliant on managed bee colonies for food production - transporting beehives all over the country for crops such as almonds or blueberries.

Alarmingly, many wild bee species are on the decline due to habitat loss, pesticide utilisation and the severity of climate change. This is a cause for significant concern - not just because it impacts our ecosystems and food security but also affects human health. To tackle this global issue in insect numbers, urgent action is required.

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