Unsure What's Going On In This Hive

[blackforest beekeeper]

Yes.  Number of mites per 100 bees = percent.   

Example1:
Sugar shake method
1/2 cup bees.  (300+ bees)
18 mites counted
Divide by 3 =
6 mites per 100 bees
Multiply by 1.3, factor for sugar vs alcohol
    6 x 1.3 = 7.8 mites per 100 bees. Call it 8

This example is 8 mp100 = 8 percent.  Infestation and contagion. Attack level. Get out the hard treatment arsenals.


Example2:
Sugar shake
1 cup of bees (600+ bees)
12 mites counted
Divide by 6 =
2 mites per 100 bees
Multiply by 1.3, factor for sugar vs alcohol
    2 x 1.3 = 2.6 mites per 100 bees. Call it 3

This example is 3 mp100 = 3 percent. Control and manage level.  Use whatever IPM, soft treatment, or treatment free method of your preference.

thanks, HoneyPump!
yes, it is more accurate, I am sure. So if necessary....sometimes one might have to be fast.
As for the factor of 1.3: I found a link....
https://bienenkunde.uni-hohenheim.de/fileadmin/einrichtungen/bienenkunde/Varroa/Brunnemann-Stubbe_2011_db-ADIZ-IF_Bienenprobe_mit_Puderzucker_-_Neue_schonende_Varroa-Befallsmessung.pdf
without having to be able to read it: look at the graph on the 2nd page. Shows counts comparing alcohol-wash and sugar-roll. So they seem to be pretty congruent.
The factor 1.3 in my eyes allows for fault on behalf of the applier: powder-sugar not dry enough, circumstances not dry enough, bees in the cup for too long (start producing moisture).

so my little slight-of-hand calculations weren`t so bad comparing natural drop-down and one of these lab-like-methods. I`d be applying treatment soon with aournd 5%, too.

Couple years ago or so there was some talk of a carbondioxide-method, don`t know what became of that one.

@HTP: I guess You don`t sample every hive? Do You do something like Ian Steppler?:
https://www.youtube.com/watch?v=6osr7PNdN2M

[TheHoneyPump]

    -  @HTP: I guess You don`t sample every hive? Do You do something like Ian Steppler?:   -

Yes.

If you have a few hives, less than 10, just go ahead and sample every hive.  If you have more or many, then setup your sample size based on statistics tools. Do not be random about how many hives to check.  Use statistics to put some science and confidence behind the number of colonies you will sample. 
Not everyone likes math nor has any idea of exactly what I just said actually means.  So Google is your friend and partner with this.  Look for, search,  - statistics sample size - or - sample size calculator -.  You will likely find some easy reads and also be able to find some simple tools that allow you to online calculate the sample size (number of hives) you need to check to have confidence that the results will represent what you have across your apiary.