Just when you think you are beginning to understand how to deal with Varroa along comes a surprise.
I have two colonies one I started last year and the other split from the original, later in the year. Both were treated with Apigaurd in August and oxalic acid vapourisation in December. Mite drops after treatment were what I would call typical. My original colony has dropped the odd mite since, however the newer colony suddenly started dropping around 10 mites a day at the end of March, which I assumed to be a the result of a mite invasion from a robbed out dead colony somewhere nearby. Previous experience down south led me to believe that as the spring advances Varroa numbers drop, so I didn't treat. However this one went into overdrive with daily mite drops soon over 20 and heading for 30. Icing sugar dusting confirmed we had a problem. The next step was oxalic acid vapourisation. So off with the supers and in with the Varrox. The first treatment dropped over 300 mites in the first 24 hours and over 800 within the week. I applied a second dose of OA and have over 600 drop in the first day. I am guessing but the total mite population must be several thousand and I will keep going with the OA treatments until mite numbers have dropped right down. The question is why does one colony not have a problem and another a few feet away gets overwhelmed. Is it this particular colony which are not very good at defending themselves or I have the bees picked up a local strain of fast breeding mites?
I have two colonies one I started last year and the other split from the original, later in the year. Both were treated with Apigaurd in August and oxalic acid vapourisation in December. Mite drops after treatment were what I would call typical. My original colony has dropped the odd mite since, however the newer colony suddenly started dropping around 10 mites a day at the end of March, which I assumed to be a the result of a mite invasion from a robbed out dead colony somewhere nearby. Previous experience down south led me to believe that as the spring advances Varroa numbers drop, so I didn't treat. However this one went into overdrive with daily mite drops soon over 20 and heading for 30. Icing sugar dusting confirmed we had a problem. The next step was oxalic acid vapourisation. So off with the supers and in with the Varrox. The first treatment dropped over 300 mites in the first 24 hours and over 800 within the week. I applied a second dose of OA and have over 600 drop in the first day. I am guessing but the total mite population must be several thousand and I will keep going with the OA treatments until mite numbers have dropped right down. The question is why does one colony not have a problem and another a few feet away gets overwhelmed. Is it this particular colony which are not very good at defending themselves or I have the bees picked up a local strain of fast breeding mites?