Treatment Timing Tips

Treatment Timing Tips

by Jack Griffes
Onsted, Michigan

I have bought used equipment and the few remaining live colonies from folks that had, in effect, left their colonies untreated by putting the strips in late and where the cluster made no contact with them. Dead colonies with four strips (2 per Deep box) in them (put right where the old Apistan directions said to put them) and a thoroughly discouraged ex-beekeeper to boot. The lesson - make sure the bees make contact with a contact miticide or it does no good spending the time putting it in the boxes.

But isn't there more to it than that? What about the high losses experienced by those that did put the strips in contact with the cluster after taking off the honey from the Fall flow? Shouldn't treating then insure there is less brood for the mites to hide in thus making for quicker and more nearly complete mite kill? Isn't that what we've been told dozens of times? Lots of beekeepers that put new strips in after a great Fall flow are left scratching their heads when a quick peek sometime November - January shows over half the colonies dead and the bulk of the survivors looking like they don't stand a chance either. "I treated them and they still died - what gives?" is thought then spoken aloud to others that did the same.

I think I can offer some insight into why late treatment often fails to prevent high loss. Perhaps you already know what I am about to tell you. You undoubtedly recall that Apistan treatment was initially advised during a broodless period - thus the mites would be on the bees and the treatment would give rapid and near 100% kill of Varroa mites. This is, of course, true if the purpose is simply killing the mites. My intention when I treat is not to kill the mites but rather to save the colony - I of course must kill a good portion of the mites to do this (except in the most resistant colonies that keep the mites down themselves and are left untreated for further testing toward HIP breeder status). So with that intention (saving the colony) in mind we must look at things differently. Simply killing the mites when you finally get around to it means you have, in effect, willingly let the mites inflict fatal damage on the colony - then you get your revenge by killing the mites - laterthe colony dies. To me that seems like throwing your treatment time and money to the wind. My guess is it feels like that to you too.

It is true however that killing the mites in colonies destined to die anyway may still help save the survivors from being overwhelmed with mites brought in by home seeking bees that have abandoned colonies undergoing breakdown (crashing). If only one mite per home seeking bee comes in (a bee can easily carry more than one mite) and one thousand bees pick the same strong colony as their new home you can see that their mite load can dramatically increase in a day or even in an hour. It is this problem that makes twice a year properly timed Apistan treatment advisable.

So what is it that mites do that causes that colony that was so strong and heavy in the early Fall to die a month to three months later? Well we have learned from scientists both in the USA (Hoopingarner) and in Europe (Büchler and others) that are working on breeding Varroa resistant bees (as we in HIP are also) that a bee that has just one mite in her cell during development will have her lifespan cut by approximately 20-40%. IF she has two mites her lifespan will be cut yet more. With one mite in her cell she will emerge approximately 10% underweight and will not be able to produce high quality brood food as well due to damage to or perhaps underdevelopment of the hypopharyngeal glands. We have learned other things too but let's keep this short and just deal with these two items: reduced longevity and reduced brood feeding ability. Let's suppose that in your area the bulk of the winter bees need to live for six months in order for the colony to survive the winter in good shape(strong). What happens if you whack 20% off that six months? Well you have winter bees that only live 4.8 months - they die too early - right in the heart of the early brood rearing when they are most desperately needed. If you whack 40% off you have winter bees that only live 3.6 months. Now remember that is what happens with bees from cells that had only a single mite in them!! They won't live that long if many of the Winter bees developed with two mites in their cells. Remember too that those bees from mite infested cells had damaged or perhaps underdeveloped hypopharyngeal glands which means they could not feed brood as well which MAY of itself reduce the longevity of the next crop of bees even if the mites are killed (creatures raised on reduced nutrient rations generally have shortened lives).

The most important treatment should thus be timed to allow ALL the winter bees to be reared in Varroa free cells by bees that can feed them well so that the winter bees will have normal longevity and normal brood feeding ability. This treatment will vary in time from area to area due to differences in Fall flows (or lack thereof) and also differences in tendency to rear brood late or shut down early. Generally in the North this means that the "ideal" time to begin treatment is about 15 July - 1 August. This poses a huge conflict as many beekeepers are in the heart of their honeyflow then and cannot treat - yet if they don't treat then they will lose MANY of their bees. Treatment that begins after 15 August in all too many cases is little better than leaving the colony untreated - so far as saving the life of that colony goes (once the mites are well established in an area [ 2-3 years ]).

The second most important treatment should be timed shortly before colonies are likely to get a few flying days. This will be around early March in the North. Why treat then? Especially why re-treat a colony you cleaned up before Winter? There are two primary reasons: 1) mites brought in on thieves returning home with mites as well as honey (gathered from weak survivors) and 2) mites carried into strong colonies on the bodies of home seeking bees whose colonies are now crashing. Thus the late Winter or VERY EARLY Spring treatment is done to insure the colony does not suddenly become heavily mite infested due to LARGE mite donations from crashing colonies that barely scratched through the Winter AND also to clean up any reinfestation that occurred after you pulled the strips the previous Fall (due to early crashers within flight range that weren't treated early - maybe including that swarm or two that got away last year).

So it seems wise (for now at least) to treat twice a year with the label recommended number of new Apistan strips (one strip per five frames of bees) in direct continuous contact with the cluster for the label allowed time period. It would also seem wise to time those treatments to match with the realities of mite parasitized bee biology. This means treat beginning late Summer and treat again late Winter or very early Spring. By doing that as well as doing all the standard things like keeping diseases under control you will stand a lot better chance of having to worry about problems like controlling swarming, and getting supers on them. In my opinion those problems are much to be desired over dealing with the dead.

But as is true so often each solution to one problem seems to bring with it a new set of problems. Like - how can I possibly treat that early - that is right when our main honey flow is on? Perhaps we can bring out some possible solutions to this and other related problems another time.

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Changes last made on: 18 March 2000
Accessed times since 23 Oct 1997.