>From sci.agriculture.beekeeping
---
> Matthew Pollard <[log in to unmask]> wrote:
> has anyone done this? what size screen do i want? What did you use for
> sticky stuff?

Hi, my husband made 6 screens to use in our hives.  They are great.
He used standard window screen.  We got aluminum sheets from our local
newspaper, cut them to fit with tabs to pull out of the hive (very
important).  We coat the aluminum with vegetable oil that we keep in a
large green lemon juice squeeze bottle.  If we are not counting mites,
we clean them once a week with an old sock and  apply new vegetable oil.

Here is some correspondence with Dadent and  our state bee guy that is
real interesting.

Dadent letters:

> Hi, I just wanted to make sure.  We have the varroa mite screens on our
> hives with sticky boards underneath.  Of course I lost  the instructions
> and now I can not even find your catalogue.  And now I am counting
> mites. I am monitoring 6 hives and the most I have found is 50 mites
> in 4 days.
>
>   Questions:
> 1.   I am pretty sure your instructions said something like, you would
> have an infestation you would have to treat if you counted 100 mites in
> 48 hours (without strips hanging).  Is  this correct?
>
> 2.    I can only see the large brownish red oval mites.  What about
> immature and so on that I can not really see? Is there something I
> could do to calculate them in?  Is that important?
>
>  3.   I tried doing a grid and count the mites in the grid, but some
> of the time I only have one, and a lot of the time I have none.  Can I
> use this method (so much faster) or would I be risking miscounting?
>
> Thank you for your time.  I am very happy about the screens, I feel it
> is wiping out varroa mites, these guys are dead and out of there.

Answers

1.  yes

2.  The immature mites and very small males are inside cells feeding on
developing brrod.  The lage reddish oval mites are female that are newly
emerged.  Hard to calculate and quantify the mites not seen.  That is
why the rule of thumb of x amount in 48 hours  has been chosen.

3.  If you are only trying to identify the threshold of 100 mites in 48
hours then the grid system with only 6 hives may be misleading.


At this time of the year the bees are out reproducing mites.  When fall
comes and the bee population decreases and the mites doesn't thats when
your ratio of mites to bees gets overwhelming.  A varroa screen is great
but you may want to use drone comb and Formic Acid in late ssummer to
stay ahead.

Take Care,
Jerry Hayes

And to Eric Mussen, California
> Being our state apiarist, do you agree with this (Dandant's )
> guideline?

This guideline, as you call it, or an "economic threshold" as pest
management specialist would call it, probably is as good as any.  The
problem is that a colony can handle up to 10,000 mites with little
damage or loss of productivity, if the mites are not vectoring RNA virus
diseases.  If the viruses are around, only a few hundred mites will be
devastating.  Do your bees or the mites in them have "deformed wing
virus?"  Your only clue is seeing dead pupae or very young emerged
workers that have runty or terribly malformed wings.  Their abdomens are likely
to be shrunken, too.

>I have counted 30-60  mites in 48 hours. I have counted 50-80 mites
>after one week.   I put Apistan strips in the fall and in early spring
>we did not have any mites so I did not use them in the spring.  I have
>not seen any chewed wings recently and only 2 mites on bees out six
>hives

Drs. Keith Delaplane and Michael Hood suggest that the economic
threshold in the southeastern U.S. is between 59-187 naturally fallen
mites, per night, in August, and 0.6-10.2 mites in February.

>Yesterday I tried putting Tobacco in my smoker (about 10
>cigarettes).  According to what I read, you are supposed to close the
>hive for one minute which I didn't do.  The bees fled from the smoke.
>I will examine the boards for mite drop after 48 hours.

There was a special, high-nicotine tobacco product on the market
for this purpose, available for Joel Willard Productions, 61 S. Herbert
Road, Riverside, IL  60546 [(708) 447-2291] or FAX (708) 447-1158.

>My questions are:
>Could I make a grid and count the mites in the grid and still be
>somewhat accurate?

Yes, grids will work fine, but they have to be "fair."  One
researcher made a grid with one inch squares on it.  Using a random
numbers generator, she blacked out three-quarters of the squares.  She
multiplies what she finds in the remaining squares by 4.

>I think there are more mites in the center strip
>under the brood nest where I can pick up maybe 2 in a 3" grid, but then
>a lot of the grids are empty..  I am not sure how to work it.

If you know that only certain places are likely to have mites,
use that as your "world."  Divide it into squares, "randomly" eliminate a
significant portion of the squares (don't just pick a bunch, your brain
isn't random enough), count the remaining squares and multiply by the
appropriate factor.

>Also, I have been finding a beige translucent mite.  Is that an
>immature or do they shed their skins like a molt, do I count those as
>well?

Only count the dark ones.  Immature female mites are lighter in
color, but they are doomed, reproductively, so they don't count.
The mites do molt as they grow, but the shed skins only show up
after the bee emerges from the cell and the workers clean up the
cell for the next larva.

Eric.