Malcolm’s Topical Tips – 2015 June 13


Traditionally beekeepers do not start to think about treating disease in their colonies until August. The reason for this is varroa takes time to build up in a colony and it is at this stage in the year that you will really begin to see bees with deformed wings.

Varroa which is causing DWV (deformed wing virus) is only one of many viral, fungal and bacterial infections that are probably present all the time at low levels in every colony. Varroa is the number one enemy at present and I will be suggesting some strategies for dealing with it, but other infections should not be ignored and at the beginning of this missive that it what I shall be dealing with.

The worst infections from a novice's point of view are EFB (European Foul Brood) and AFB (American Foul Brood). Outbreaks of AFB don't seem to be that common but EFB has been a problem in this area.

Suffice it to say that if you see in your hive melted down larvae this could be EFB. The larvae look like 'snot'! When EFB starts to take a hold you may not see many larvae like this as, to begin with, the bees remove them. However it is the very act of removing the larvae and cleaning out the cells that is spreading the disease further. If nothing is done to treat eventually the hive will start to smell fishy, as bacteria start to hasten the decomposition of the melted down larvae (these are not being removed by the colony as they have become overwhelmed by the disease).

The above scenario would entail you contacting firstly someone in the association and then the bee inspector who comes out, and using a lateral flow device tests for the presence of EFB. A simple test you can do yourself is to take a pair of tweezers and pull one of the suspicious larvae apart. If a ball of yellow pollen can be seen, then probably everything is alright. This is because EFB is a bacteria that feeds off pollen in the gut of the larva and if EFB is present the bacteria will have already digested the yellow pollen.

Yellow pollen in the gut = larva hasn’t died due to starvation; EFB may be present at an early stage or you are mistaken and it is sac brood or another fungal infection.

White snotty mess when the gut is pulled apart = larva has died of starvation; EFB likely

One of the commonest diseases for beginners is chalk brood. . In the initial stages you will see dead larvae in the frames that have died. These larvae have become mummies that are hard and look like chalk. This is a fungal infection and if left unchecked the mummies of the dead larvae turn from looking like chalk to a dark blue colour and this indicates that the fungus is producing spores, which will further pollute your hive and slow up its expansion. You will find dead mummies on the inspection board if you have it in. If you leave well alone the bees usually clear out the mummies, but only if the colony is strong. I have found that beginners often leave their inspection boards in and the lack of air circulation seems to worsen this problem. If you have open mesh floors, then let the bees have plenty of air. The inspection boards are not intended to be left in for any great length of time!

In cold summers sac brood can become a problem. Beginners muddle this with EFB. The larvae curl up in an odd way and it has been suggested that this looks rather like a Chinese slipper. The larvae do have a slightly melted down look but you can still see the Michelin tyres on them. They tend to turn a dark brown colour as they die. Once again this usually clears up.

If you have the luxury of keeping several colonies, I personally would try and combine two or three hives, as with more bees they will better be able to cope with these fungal infections. EFB, of course, is another matter. If you have a number of colonies the best bet when EFB is confirmed in one hive is destruction (inspection floor added, entrance sealed with gaffer tape, petrol poured through the crown board at night). Remember to seal up the hive so your other hives do not go and rob out the infected honey. Then burn all frames. The box should be torched as should the crown board, floor and roof. A Beekeeper should have a blow torch anyway so as to regularly clean his equipment. Remember hot water and soda crystals are insufficient to kill the bacterial spores of EFB, which can only be eradicated by using a blow torch. Bacterial spores are even resistant to boiling water!

Now to varroa. Some of you will have read the article in the BBKA news and will be thinking you should perhaps just do nothing and the bees will find a way of dealing with it. Don't! Unless you have got a huge number of colonies.

Colin Stocks swears by icing sugar and dusts this onto the frames each time he looks at his colonies. This will knock off a small percentage of phoretic mites and delay the build-up of mites in a colony. He does nothing else and that can only work, in my opinion, if you have a really good strong colony. Something beginners rarely have.

A late summer treatment with thymol. The bees try and remove the thymol from the hive and this irritates them so they keep cleaning themselves. Probably the thymol gets transferred to the varroa mites damaging their delicate outer carapace and this causes the demise of most of them. However beginners make the mistake of not starting the treatment early enough. To be really effective temperatures for the whole period of the treatment need to be well above 15 degrees. So you will only get the best out of the product if it is put on mid or even early August. By the time we visit the French in Normandy in late August their winter treatments are already complete. The inspection board needs to be put in, and I have even resorted to putting gaffa tape over the back of the hive so as to guarantee as little ventilation gets into the hive as possible. You want the volatile oils in the product to irritate the bees to the maximum as this will try and make them remove it from the hive and in so doing pass it around among themselves thereby guaranteeing a good mite drop. An eke is needed for the tray of Apiguard. If you have no eke , buy Apilife Var, the biscuits of which are laid directly on top of the frames. So if you have not yet got your late summer treatment from Paynes or Ben and Maggie Pratt, then order it now in readiness.

When a colony swarms you also have options. If you have a virgin and she is about to come into lay, Oxalic acid is an option. I have never wanted to do this fearing I might damage the new Queen. However inspired by Jonathan Coote in West Sussex I am now using a weak solution of lactic acid. This is no stronger than lemon juice but when sprayed on the bees they concentrate it down and this damages the delicate feeding parts of the varroa. This knocks off 70% of the mites on the bees. However bees need to be excluded from their supers. This will hopefully mean that in August I won't have the huge numbers of varroa in these units that I have had in the past. Helen has mixed up the correct quantities and you should contact her if you want to try this option.

If you have a number of hives, you may be able to take a frame of eggs and young larvae and introduce it into a hive where the Virgin is about to come into lay. Mark the frame clearly and when it has been sealed remove it. It will be full of mites as they will not have been able to breed for at least five weeks, so will have been desperate to dive into the nearest brood cell. Uncap the sealed cells and you will see the number of mites you have trapped.

I won't now deal with winter treatments. That will be for another time. As ever I hope the above is helpful.

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