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Discussion Starter · #1 ·
So...a little back story.

I treated my hives with Formic Pro last week of July. Around the middle of August I did alcohol washes to determine if it was effective and what infestation percent was present. I sampled prolly 60-65 percent of a total of 30 hives to get a realistic sampling. The highest percent I got was 4 mites/300 bees with most just one or two per 300 bees sampled. I was quite happy with what I saw.

Today I sampled 6 and got a high 8/300 bees which in my mind seems pretty good considering the brood nest consist now of 2 center frames in single boxes of nine frames.

I also have 10 five frames that were not treated and one came back with a 7 percent mite load. In those hives I would guestimate maybe 100 - 150 sq2" of brood covering both sides of the center frame with very little open brood. I did not see any signs of brood cannibalization but one DWV bee. I plan to OA dribble all of those soon.

So my main question is, what percent of a mite load is too high when the queen has practically stop laying as she preps for winter? and a side question can I dribbles soon and then again say early December? It is not uncommon to have mild spells late November early December where I have the bees.

I'm 30 miles south of Seattle.
 

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Discussion Starter · #4 ·
1%, you probably broke out the big treatments too early.
The one percent level was observed in mid August after I treated in July, I didn’t to counts prior to treating as historically that has been when I see increasing mite levels. Late July or early August is when the summer nectar dearth arrives snd that is when I do my summer treatment.
 

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I do OAV 3 times in the Summer, and wait on the pricey treatments till late Aug early Sept., or they will just get reinfested.
Problem with that is you are allowing mites to keep spreading virus in the mean time. It has been often said that it takes two rounds of brood clear of virus effect before the winter brood is nursed. Quoted as time needed for the viral titre to drop after mite removal.

I agree that reinfesting after you think they are all gone could lead to the winter bees to be carrying a damaging level of varroa.

Why limit summer treatments to 3? To heck with the expense; give it to them!
 

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In a sense, you obviously want as few mites as possible at all times. However, you're exactly right that higher mite levels at this time of year are expected as the amount of brood in the colonies goes down. Your mite monitoring method only counts the phoretic mites, and with fewer brood cells you can expect a larger percentage of the moderate mite population to be in the phoretic stage. You could certainly treat now, but the published treatment thresholds generally would suggest that October mite levels of about 2.7% are not high enough to predict that your bees will likely die from mites and mite-associated viruses this winter. However, I would say those hives are great candidates for a winter oxalic acid vaporization or oxalic acid dribble, since either method will let you clean up those mites while they're riding the winter bees, and will prevent them from causing trouble (and starting to grow their numbers) next spring.
 

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Problem with that is you are allowing mites to keep spreading virus in the mean time. It has been often said that it takes two rounds of brood clear of virus effect before the winter brood is nursed. Quoted as time needed for the viral titre to drop after mite removal.

I agree that reinfesting after you think they are all gone could lead to the winter bees to be carrying a damaging level of varroa.

Why limit summer treatments to 3? To heck with the expense; give it to them!
Well honeys on till late July, then I oav 3 times over 3 weeks, and put Apivar or Apiguard etc on to where it ends treatment at the end of Sept when the Bees that raise the Winter bees are emerging.
been working so far. That stuff is expensive for 25-30 hives.
Apiary Plant Wood Beehive Pollinator
Beehive Pollinator Apiary Insect Green
 

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Anything getting above 3/300 bees in the fall is bad.

A few years back, when other mite bombs were in the area, a solid % of them were 5% in the fall, none of them perished in the winter.

They were down to 0% by November.
 
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3 OAV's 7 days apart? Yes the Apivar is pricey. With your shorter winters you can probably tolerate a higher % mite load but the lower the mite levels average, it helps keep viral levels from rising. This can sneak up over a period of several years. Dont get complacent. Some operators have been hit with the 5 year collapse. Some several times. There has been a fair bit of chatter about the paralytic virus occurances being on the rise.
 

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The adherence to the 7 day spacing, is that adherence to letter of the law or do you feel that is optimum bang for the buck? I would feel I was leaving a lot of money on the table.:unsure:
 

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Discussion Starter · #14 ·
In a sense, you obviously want as few mites as possible at all times. However, you're exactly right that higher mite levels at this time of year are expected as the amount of brood in the colonies goes down. Your mite monitoring method only counts the phoretic mites, and with fewer brood cells you can expect a larger percentage of the moderate mite population to be in the phoretic stage. You could certainly treat now, but the published treatment thresholds generally would suggest that October mite levels of about 2.7% are not high enough to predict that your bees will likely die from mites and mite-associated viruses this winter. However, I would say those hives are great candidates for a winter oxalic acid vaporization or oxalic acid dribble, since either method will let you clean up those mites while they're riding the winter bees, and will prevent them from causing trouble (and starting to grow their numbers) next spring.
That's kind of what I'm thinking as I fully expected to see an increase in the wash as the brood nest has significantly reduced. I am, however, a bit nervous at that one fiver that came back with a 7 percent load.

Anyahoo...I did a OA dribble on the five frame nucs today, and even though its contradictory to you should not OA dribble more than once a year I plan to do another OA dribble sometime mid November when little to no brood should be present.
 

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Discussion Starter · #15 ·
Anything getting above 3/300 bees in the fall is bad.

A few years back, when other mite bombs were in the area, a solid % of them were 5% in the fall, none of them perished in the winter.

They were down to 0% by November.
If I'm reading your post correctly, you had many in the 5% range after late September, but knocked the back to a close to zero, with out any ill effects stemming from the mites?
 

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Your mite monitoring method only counts the phoretic mites
That's not correct. Mites infest the nurse bees, they are not phoretic at that time. As a matter of fact, there's a fair argument that they are never phoretic willingly.

When you do a wash, you are getting a count of any mites found in the sample; both actively feeding, and those seeking another gig. It is a representation of the infestation rate, not a count of those moving around.

Anyahoo...I did a OA dribble on the five frame nucs today, and even though its contradictory to you should not OA dribble more than once a year I plan to do another OA dribble sometime mid November when little to no brood should be present.
The reason OAV is generally considered safe is that bees do not ingest the OA. Multiple dribbles can kill a significant number of your bees:
Oliver said:
As far as winter broodless dribbling, it is absolutely critical to treat them only once, with exactly the right amount and concentration of OA. More than one winter treatment clearly hurts the bees. Charriere and Imdorf (2002) found that colonies treated with 5-6 ml/seam of 3% OA were only 85% the strength of controls by April 25.
 

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"That's not correct. Mites infest the nurse bees, they are not phoretic at that time. As a matter of fact, there's a fair argument that they are never phoretic willingly."

Here I think you are quibbling about semantics.:)

I think the term phoretic, in its strict definition does not entirely convey the significance to varroa and bees. The general take away seems to mean that whenever they are not under cappings. While they are not under cappings, whether they are moving on their own power or hitching a ride, they are greatly susceptible to treatments.

"When you do a wash, you are getting a count of any mites found in the sample; both actively feeding, and those seeking another gig. It is a representation of the infestation rate, not a count of those moving around". This I agree with.
 

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We base treatment on the # of mites/300 bees.


it's not a way to determine the exact # of mites in every cell on every larva in the entire colony.


Based on that metric, we prescribe treatments.

Sort of like doing a lice test on humans, see a few lice? Well that's bad, time to treat - they don't go in and count every single lice to determine exactly what % of lice are on the entire skull....
 

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Discussion Starter · #20 ·
The reason OAV is generally considered safe is that bees do not ingest the OA. Multiple dribbles can kill a significant number of your bees:
Yes...I realize the literature states that multiple dribbles hurts the bees, but high loads especially will likely kill them off by late winter. I don’t like having to treat twice, but I like having empty boxes in late winter much less. I’ve looked for information about how much harm there really is to the bees with multiple dribbles spaced 30 days, but didn’t find much other than uts not recommended. If anyone can shed lightbin how bad it is to multiple dribble kate in the year, that would be great
 
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