Varroa count

[Levitt53]

I've just done a varroa count via the inspection board for 3 days.

1. Swarm in wooden hive which had high count in the autumn so was treated with Apiguard - 1 varroa mite seen now. I assume this doesn't need treating with oxalic acid now.

2. Purchased colony in poly hive which swarmed and were queenless for a while. The autumn count was low so they weren't treated. - 5 mites seen.

I probably shouldn't have done a count this late but hey! My general inclination is to just treat them when necessary so I think I'll leave treating with oxalic acid this year. Does this sound reasonable?

 

[jenkinsbrynmair]

Originally Oxalic trickling in winter was designed as an 'instead of' rather than a supplementary treatment. It's only done in winter as the colony needs to be brood free and multiple tricklings can have a negative effect on the colony - unlike sublimation (which can be used in September brood or not as long as you do it three times - once every five days)
If you gave them an effective treatment in September then there is no need for a winter treatment.

 

[charlievictorbravo]

If you were to run your 'natural drop counts' through Beebase's Varroa Calculator you'd probably get a response to say that you have not measured to drop over a long enough period - I think they recommend 7 days. That is because the daily count can vary a lot over a short time.

However, you're at where you're at and a drop of one mite a day is not significant, I have three colonies; one is dropping about one mite a day and will not be treated, one is dropping three mites a day and I'm undecided about that one and the last is dropping nine mites a day and will be treated when I get "a round tuit".

One of the principles of Integrated Pest Management is to only treat when you need to, not because it's the 14 December.

CVB

 

[Erichalfbee]

I wouldn't bother
I had the odd varroa on the inspection tray and vaped the hives maybe 10 days ago
I got zero zero zero zero 10 12 in three days after vaping

 

[jenkinsbrynmair]

varroa are never going to disappear completely, just be happy that only the odd one is dropping - a trstimony to your timely and proper treatment in the autumn at a guess

 

[masterBK]

if you sample over a week or two and get an average of one mite a day dropping through the mesh at this time of year probably represents a population somewhere of between 250 and 450 mites. I am getting these sort of numbers dropping in a few of my hives so will be treating them next week.

 

[Levitt53]

Thanks all. I think I will leave it now and inspect again (for longer) when spring approaches.

 

[Eyeman]

I like to think ahead:
Lets say you have 50 mites in the hive in December. If they double their numbers ever month then by May you'll have 1600- ie. over the treatment threshold. May is my busiest month with queen breeding, swarms control etc so last thing I want to do if worry about mite control.
If you use oxalic acid now and it's 90% effective then you have 5 mites in Dec- this means that you won't exceed the treatment threshold until August / September which is just when I'm taking the honey supers off and the season is winding down- it's a good time for me to treat.

 

[Hivemaker.]

I like to think ahead:
Lets say you have 50 mites in the hive in December. If they double their numbers ever month then by May you'll have 1600

Assuming, among other things, that no mites at all die between December up until May, and there is brood during all of this time for them to breed, is this also counting male mites.

 

[Eyeman]

Assuming, among other things, that no mites at all die between December up until May, and there is brood during all of this time for them to breed, is this also counting male mites.

It's all assumptions I agree.
Don't we all all want to start the new year with as few mites as possible?
So OA sublimation during winter is a no brainer!

 

[Hivemaker.]

So OA sublimation during winter is a no brainer!

Maybe, but not had any problems and have only used oxalic twice in the winter since varroa arrived, two separate winters, one treatment, and that was trickling the stuff, worst thing I ever did.

 

[MerryBee]

I have 6 colonies. All were treated with Apiguard in September.

I monitored the natural mite drop over 7 days in late November.
1 colony dropped 11 mites per day over this period. The rest were 1 mite or fewer per day.

Last week I treated all of them with vapourised OA , and then monitored the mite drop every 2 days for 8 days.

The worst colony has dropped 700 mites over the last 8 days (EEK!). The others have dropped between 14 and 180 mites. The one which has dropped 180 mites, dropped just 1 single mite over the 7 day monitoring period in November.

So my conclusions
1 Apiguard is sometimes not at all effective, but I have no explanation for why this.
2 Natural mite drop is an unreliable indicator of infestation. - well we already knew this didnt we
3. Its worth treating all colonies, whatever the natural mite drop indicates.
I certainly would not want to be starting the new season with 180 mites in a colony.

 

[Eyeman]

Hi Merrybee
Thanks for an interesting post.

1 Apiguard is sometimes not at all effective, but I have no explanation for why this.

Did you check the mite drop before Apiguard?
I don't think Apiguard wasn't effective- just consider this,
Say you had 2000 mites in September and Apiguard has a 95% kill.
You would have had 100 mites left in September.
If there was still brood present these 100 may have doubled each month.
So come OA treatment in December you have 800 mites!
Are you going to give the hives another couple of OA vaporisation incase there is still brood present?

 

[MerryBee]

I checked all colonies for brood the day before the vap, as recommended by LASI. It was warm (12 degrees) and didnt cause a problem as I was in and out in about a minute. Only one colony of the 6 had any sealed brood and i removed it. So no need for a second vap.

 

[Erichalfbee]

I checked all colonies for brood the day before the vap, as recommended by LASI. It was warm (12 degrees) and didnt cause a problem as I was in and out in about a minute. Only one colony of the 6 had any sealed brood and i removed it. So no need for a second vap.

Now are you going to hang fire till next December to vape again as per LASI ?

 

[MerryBee]

I expect to have to treat again in September, either with Apiguard/ ApiLifeVar or maybe with vaporised OA, for the benefit of the winter bees.

I also monitor the varroa drop for a week every month, which gives me a reasonable idea of the rising levels of infestation. Well, much better than relying on a one-off count, anyway.

 

[Erichalfbee]

I expect to have to treat again in September, either with Apiguard/ ApiLifeVar or maybe with vaporised OA, for the benefit of the winter bees.

I also monitor the varroa drop for a week every month, which gives me a reasonable idea of the rising levels of infestation. Well, much better than relying on a one-off count, anyway.

I ask because this whole thing of making sure there is no brood by destroying any that is there is so that you can have virtually 100% kill. According to LASI this gives you a years control with "ordinary" bees and 18months with one of their queens. Is there much point in opening the hive if you are going to treat one or two times in the rest of the year?

 

[jenkinsbrynmair]

Still this misconception that winter treatment is suplemental to rather than an alternative to autumn treatment