Agriculture Reference
In-Depth Information
goop on the side of the jar. After rolling and shaking the jar for several minutes, count
the mites and estimate the colony's mite population.
Another technique is to take the same size jar, preferably with the two-part cap used
for canning. Replace the inside lid with a circle of small mesh wire (but larger than win-
dow screen). Capture about 300 bees, but this time pour in ½ cup (60 g) of powdered
(105) sugar. Roll the bees in the jar for several minutes. The tiny sugar particles cause
the mites to lose their grip and fall off the bees. After rolling, pour the sugar and the
mites out of the jar through the screen onto a white surface. The mites are easily visible.
Count them, and then estimate the mite population in the colony. The bees can return to
the colony, unharmed.
There are several downsides to both of these methods. The counts are less than pre-
dictable. Somewhere between five and forty mites is a good measure of when you
should do something. Further, these thresholds aren't based on time of year and size
of colony combined as are those with the sticky board counts (see below). For now, I
recommend the sticky board method. Even with its drawbacks it seems to be the best
method.
Sticky Boards
Earlier it was recommended that you purchase a screened bottom board with a rear-ac-
cess removable tray that would slide in beneath the screen. Varroa mites are the reason.
You'd think that the bees in your brand new package would be pretty healthy, wouldn't
you? Why not check and see? Set up your screened bottom board and slide a sticky
board (available from most bee suppliers) beneath the screen. Anything that falls from
above the screen—from the bees or the frames above—will pass through the screen but
be captured on the sticky board below the screen.
Adult varroa mites aren't always reproducing in cells (it's about an 80:20 percent
split, in-cells to not-in-cells). Those not in cells often spend time on top bars and on the
comb waiting for an adult bee to walk by so they can catch a ride and feed on them.
They nestle down between a couple of segments for a while, possibly moving around
the colony.
During this process they may be brushed off, let go, slip and fall, or die. Some end
up falling to the bottom of the colony, through the screen, and are caught on the sticky
board below. This happens constantly and scientists have, for the most part, figured out
how many will fall every day in small, medium, and large colonies and how many in
the spring, summer, and fall.
Once you know how many mites have fallen, how big the colony is, and what time
of year it is (and to some degree what kind of bees are in that colony), you can estim-
ate how large the varroa infestation is. Most important, you can then determine what
you should be doing to change that population. Your decision to take action should re-
