In my last apiary notes I mentioned that we need to consider our varroa treatment which should start as soon as honey is removed – ideally by early August. My opinion is that varroa levels should be as low as possible before the winter bees are produced. We need bees to be as healthy as possible to survive till the following spring. If mite levels are high they can impact many winter bees and shorthen their lifespan.
There are reports that there have been issues sourcing MAQS in the UK (i.e. in short supply, if available at all) although some suppliers seem to have it back in stock now. Consequently I have been asked to give my views on the various treatments available. Over the years I have used most of the available treatments and have formed a view on each of the products. Others may (will) disagree with what I have written but that is beekeeping. Put two beekeepers together and ask them about swarm control and you will get five answers. Put them together and ask about varroa treatment one would need to locate the exit quickly!
My policy when treating my bees for varroa is never to do it when honey is present. This way I know I cannot contaminate the honey regardless of what the instructions say. For some products the honey must be removed and some say it is ok to treat with it present. I prefer to take supers away and then I know I am completely safe.
Most varroa treatments are harsh and make life for bees unpleasant. The aim of treatments is to be strong enough to kill mites but not the bees. But without treatment most colonies will die out. This statement can open a can of worms so I’ll leave it at that.
MAQS – formic acid is the active substance and you can tell as soon as the lid is removed from the container even when the pads are still in their wrapping. The smell is very strong and I wouldn’t want to be exposed to the substance for any period of time. Many people find it very effective and the treatment is over in 7 days. There are reports of it killing queens if there is not enough ventilation. Recently I heard of someone who lost a lot of bees as well as the queen when treating with MAQS – so be very careful and follow the instructions closely.
Apiguard – contains thymol in two trays and takes four weeks to treat (two weeks per tray). This product is temperature sensitive so must be used in August whilst we have good daytime warmth. My view is that it can have variable effectiveness and can also put the queen off lay at a time when I feel she should be producing the winter bees. Read the instructions carefully as mesh floors must be blanked off and ventilation restricted.
Apivar – the active ingredient is Amitraz. The treatment time is six to ten weeks using two strips per hive and is very effective. However, if the product is used each year mites can develop resistance and then it will become unusable. This happened years ago with Apistan when the mites developed resistance. So varroa treatments should be changed each year to prevent mites developing resistance.
Apistan / Bayvarol – these are similar products. Apistan contains fluvalinate and Bayvarol flumethrin. The treatment is the same as Apivar – two strips per hive for a minimum of six weeks. All treatments using strips should be removed before winter as they become weaker over time. This means that mites then can then tolerate the weaker dosage and develop resistance in this way.
Oxalic Acid – Treatment can be either by trickling or vaporisation; both are effective although vaporisation is reported to be more effective. Vaporisation requires a car battery and a hot plate plus a breathing mask as oxalic fumes are dangerous to humans. For trickling there are 3 approved products (Api-Bioxal, Oxybee and Oxuvar). I have only used the trickle method and found it to be very effective.
My current regime is a mixture of oxalic acid trickling in winter and spraying Varroamed in March / April and August. Varroamed replaces Hiveclean which was removed from the market some years ago as it wasn’t approved by the VMD (Veterinary Medicines Directorate). It has now been approved and has doubled in price as a result. This product does not kill mites but causes them to fall off the bee as they do not like the taste. So it is essential to use open mesh floors without the insert so the mites fall on the ground. The aim of my regime is to prevent mite levels becoming too high where they can cause damage to the brood – hence the different treatments during the year. The product is sprayed onto the top of brood bars. It has little impact on the bees (it does contain oxalic acid but much weaker than the winter treatment). As mentioned this is applied twice during the active season – once before supers are added and again when they are removed. Oxalic acid is then trickled between seams of bees just before xmas. Oxalic acid in winter can be used only once as it affects the gut of bees. As I mentioned earlier most treatments are harsh on bees but this regime seems to me to be the least harmful.
You may want to place the plastic insert under the floor (if the product you are using does not require the floor to be ventilated) to monitor mite drop. There can be wide variations between colonies in their mite knock down which often comes as a surprise. Personally I do not use inserts as my floors are homemade and do not take an insert. However, I regularly remove drone pupae during the main part of the season and look for mites on the developing drones. This normally gives a good indication if there is a mite problem or not. Another thing to look for are bees with deformed wings (DWV) which can indicate that there is a mite issue if many bees are affected.
There are other products on the market but I have not tried them so I have not mentioned them in these Notes. My aim here is to give an appreciation of the popular products and issues there may be in their use. But do treat with something otherwise your bees may not survive till next spring.