How to check for varroa using SBB?

[TheMasonicHive]

Hello everyone.


I saw a varroa mite on my last inspection and I have some fundamental questions about using a SBB and how to get an estimate as to what the level of infestation is.

1)  Can I just use PAM cooking spray on the tray to make them stick?  What do you guys use?

2)  It is July, and we've had some mid 90's days.  Should I put the tray all the way in or will it cause a ventilation problem?

3)  How long do I keep it in for while checking?

4)  After counting how many mites I find in the tray is there some rough mathematical way to make an estimate of the hives infestation?

5)  Is there a mite count or infestation level that could be considered "normal"?

Thank you!

[Kathyp]

you might want to do a search.  i think there was just a long thing on this.  in short, i use the OH SH&# method.  if the number of mites i see don't make me cuss, the number is ok.

there is a formula for determining mite load.  it's probably on here somewhere too.

are you going to treat?  if not, don't worry about it.

[Bighead]

There is a lot of good info at this site.  http://maarec.psu.edu/index.html

[AllenF]

I like the Kathy method.

[sarafina]

I use a thin layer of cooking oil in my trays and on the black tray I line it with copy paper so it is white and I can see the mites and SHB.

I was checking them 24 hours after I did a powdered sugar dusting, so leaving the tray in that long won't hurt.  You need to push it all the way in or the bees will be able to get into the tray from underneath and drown in the oil.   I also checked them 24 hours after I did the oxalic acid dribble and that was when I saw the highest drop.  I asked the question about counting because previously I could count all of them in the whole tray,  They build up exponentially over time and they were winning the battle with my hives with just the powdered sugar after 2 years (I did nothing my first year).

Anyway, the answer I got was 25-30 was ok.  They started counting 1/4 of the tray and if they hit 100 then they quit and determined "too many".  I had well over 100 after the OA dribble - haven't seen near that number since but I haven't checked in a while.  I opened up some drone cells and only found 1 mite in 4 cells so I was satisfied thy are ok until winter when I will do the OA dribble again.

[indypartridge]

I have a white slide-in board on my SBB's that I spray with cooking oil and leave in for 24 hours. If see more than about 50 mites in the 24-hour period, then I treat with powdered sugar. The threshold of 50 in 24 hours is what is recommended by our State Apiary Inspector.

[TheMasonicHive]

Found 9 fully grown adults in my April Package hive.  I would say there are 10 to 15 dots that were suspect.

Found 2 fully grown adults in my May Package hive.  There were 3 or 5 dots that were suspect.

I'm curious if I just keep reapplying oil and recleaning if I can make a dent in the population?

[Hethen57]

If I am understanding your question correctly...No...the oil doesn't do anything other than drown the few live varroa that fall down and help you identify that you have a problem up in the hive.  The amount that inadvertently fall through the screen just represents a tiny fraction of the infestation above to allow you to extrapolate how big of a problem you have.  The vast majority do not fall down through the screen, so it is not really an effective control measure by itself.

[AllenF]

When they fall through the screen, they are gone.   They can not make it back into the hive.   They oil if just to stick them to the board so you can count them.  When the sticky board is not in place, they fall on the ground.

[sarafina]

My understanding is the screened bottom board helps because once the mites fall through they cannot get back into the hive unlike solid bottom boards.  The oil tray is just to provide a way to count your mite load.

However, a SBB is not always enough to prevent a heavy mite load because they lay their eggs inside the cells (and prefer drones) so you have an exponential growth and most are in the cells.  Treatments and SBB only address those that have emerged.  That is why treatments are much more effective when there is a break in the brood production and why I will do my once-a-year treatment with the oxalic acid in Jan on a sunny day when it is above 50 degrees.  We never go completely broodless here in Houston and have mild winters so Jan is the best time here.

Another way to reduce the mite load w/o treatment is to replace a frame with a green plastic drone frame.  Once there is a lot of capped drone brood, remove the frame and freeze it to kill the drones and mites and replace it.  The bees will clean it up.  I have one in each hive to keep the queen from laying drone brood in my supers since I don't use a queen excluder (working well so far) and have not removed it to freeze it but it is an option if I need to.