Varroa mites and how to treat them
Honey bees, like many other insects are prone to parasitic mites and even the healthiest of colonies can run into trouble if the necessary precautions aren’t taken. Anticipating problems can certainly help you avoid any disasters.
Varroa destructor (the name paints a very clear picture doesn’t it) was originally a pest of the Eastern honeybee. Those bees have now built up sufficient ways to keep the mites under control so they can ‘co-exist’ without too much of an issue. However, as Varroa destructor have made their way from Asia to all parts of the world (except Australia), our Western honey bees have not developed the same level control and need help to fight them off.
They first appeared in Britain in 1992 and have been a problem for beekeepers ever since.
Varroa mites are actually visible to the naked eye and are around the size of a pin head. Compared to the body of a honey bee, that’s quite a formidable size. To make a comparison for a human being, that would be like having a creature around the size of a dinner plate attached to you! (We know, poor bees!) And as if that isn’t bad enough, because these crab-like mites attach themselves and pierce the skin of prepupae, pupae and adult bees to feed on their haemolymph fluid (blood), they act as vectors for diseases – and it’s the viruses that the mites transfer that are the major cause of issues.
Infestations can be spread from one hive to another through foraging worker bees that have Varroa attached them. Varroa mites like the scent of larvae and get into brood cells before the bees cap them and they will not only feed on the developing bees in the cells, but will also lay eggs and reproduce at a very fast rate.
Although varroa mites sound a little like something from a horror story, don’t be alarmed. There are way and means to stop these little creatures causing too much havoc for your bees.
How to spot the symptoms?
Varroa detection must be a routine part of your inspection schedule. If you see any of the following, it can be a sure-fire way to detect that there may be a problem.
1. Reddish or brown spots on the larvae (these may be mites)
2. Bees with deformed wings or other growth issues? This could indicate a virus within the colony
3. Varroa mites on adult bees – this could indicate a heavy infestation
4. Your bees didn’t make it past the Autumn (this can be avoided if the necessary treatment is done at the right time)
Varroa detection and count
There are various ways that beekeepers tend to detect, count and evaluate the Varroa population present in the hives before and after the honey season.
1. Icing-sugar shake method
Effective and easy, this method involves making or buying a varroa mite test jar and adding around three tablespoons of icing sugar to it. The next task involves scooping up some bees from the brood nest and while blocking the open end of the jar with one hand, giving it a shake to help dislodge any varroa mites. By shaking the sugar onto white paper, the varroa mites will be easy to spot.
Tip: Let the bees settle down a little before releasing them. They won't be hurt, but they may not be in the best of moods.
2. Drone brood uncapping
This is done by finding a frame with a large patch of capped drone brood and using an uncapping fork to pull the drone pupae out of their cells.
Please note: This method kills some of the drone brood.
3. Varroa floor debris (natural mite drop)
By using a varroa floor, you can count the natural mite drop which is usually about 10 to 15 percent. Quite simply, you can apply a thin layer of petroleum jelly to help the mites stick to the white board when they fall through the screen.
Not sure what the results mean? Don’t worry, the National Bee Unit Varroa Calculator is there to help evaluate the numbers and give further recommendations of the appropriate action.
To help treat any varroa infestations, treatment can be carried out three times per year.
1. March (before supers are added)
2. August / September (after supers have been taken off, so be sure you’ve completed all your honey extraction)
3. End of December / start of January – Oxalic acid
Do not treat during honey flow or when supers are on the hive.
Generally, it’s best practice not to treat your bees unless you are certain there may be a varroa problem. This is because the mites can actually build some resistance to treatments if they’re used too often and cut down effectiveness. Therefore, a lot of beekeepers will take the preventative measures and treat for varroa three times per year, but vary the treatments used in order to prevent a resistance from being built up.
Keep records of when you have administered treatments
You must keep a record of any medicines that have been administered to your bees for a minimum period of 5 years to comply with the legal requirements for food-producing animals.
There are different VMD (Veterinary Medicines Directorate) approved treatments available and are chosen according to the beekeepers individual preferences. However, Simon has chosen to talk through two products that will get you through the honey season, and one for your winter treatment:
1. ApiLife Var – a familiar product to many beekeepers
2. Apivar – an amitraz-based product, relatively new to the market, but fast becoming very popular
Which one is right for you?
Please take a look at each video to learn more about these products, how to use them and how they differ.
Please take a look at the video below to see Simon demonstrate how to use the oxalic based, VMA approved varroa treatment, Api-Bioxal.
The Veterinary Medicines Directorate (VMD) authorises and regulates UK veterinary medicines and enforces the UK Veterinary Medicines Regulations 2013 (VMR).
Beekeepers have responsibilities and a duty to comply with the VMR and VMD guidance. A veterinary medicine must be administered in accordance with its marketing authorisation, which in practice means you must follow the instructions in the package leaflet unless directed otherwise by your vet. Beekeepers should only use UK-authorised veterinary medicinal products to treat varroosis in honey bees and the disposal of the medicines must be done correctly.
All authorised products for bees have undergone a rigorous and thorough scientific assessment to assure their quality, efficacy and safety for bees, the user, consumers of bee products and the environment. A list of all UK-authorised products is available on the VMD’s product information database.
For any questions or further guidance regarding the treatments, please contact:
- Veterinary Medicines Directorate – firstname.lastname@example.org
- England and Wales – the National Bee Unit
- Scotland – the Scottish Bee Health Team at email@example.com
Although this may be a lot of information to take in, don’t panic. If you’re unsure, please ask and together we can keep the bees happy!