estimating level of varoa infestation

[mayayogi]

I have been using screened bottom boards on my hives with a sticky board underneath, and at the same time feeding sugar syrup with 1cc of essential peppermint oil per quart. Each hive has also been given a mixture of bees wax, canola oil, mineral oil, and peppermint oil, on a thin plastic sheet inserted into the entranced which they must track over, and thus distribute the oils around the hive. I have two hives which dropped about a hundred mites in two weeks, three hives that dropped 10, (two of these are new swarms) and two dropped zero (new packages from california). The bees seem healthy and are working hard. What kind of infestation do I have? Thanks.

[Robert Brenchley]

The UK estimate is that the mite population in winter is approximately 400 times the average daily mitefall in winter, and 30 times in summer. When the broodnest is changing rapidly in size in spring and autumn it's harder to get a realistic figure, but 100 times would be on the right lines.

Assuming you have an active broodnest, that would give around 200 mites in the first two hives, around 20 in the second three, and obviously none in the last two. At any rate, you seem to have nothing to worry about, but keep on monitoring because I'm sure you know how fast mites can breed.

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Regards,

Robert Brenchley

RSBrenchley@aol.com
Birmingham UK

[mayayogi]

Thanks Robert, that is very helpful information. One more question; How big a mite population does it take to kill a hive over winter?

[Robert Brenchley]

I can't give a hard and fast answer to this; they reckon over here that around 2 1/2 - 3000 will cause a colony to collapse, but it seems to vary a lot. Winter kill is more typical of TM than varroa, which tends to cause collapse in autumn. Of course, a hive may survive at that point, too weakened to get through winter. My local Association lost all its hives a couple of winters ago; I suspect htis was probably due to mites, though I don't know which one.

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Regards,

Robert Brenchley

RSBrenchley@aol.com
Birmingham UK