Agriculture Reference
In-Depth Information
flect the IPM discussion (see page 101), considering the pest population, the economic
threshold, and the injury levels.
Counting Varroa Mites
Approximately 75 to 80 percent of the mites in a colony are in cells, while the remaining
20 to 25 percent are mobile. Knowing that, and being able to estimate the roaming pop-
ulation, you'll estimate the entire varroa mite population in your colony. But more im-
portant, the number of mites you count on the sticky board (considering time of year
and colony size) will tell you if your IPM techniques are working, or if you need to con-
sider more aggressive methods.
Using Sticky Boards
The plastic inserts that come with some screened bottom boards can be made into your
own sticky boards. Apply a thick layer of petroleum jelly or vegetable-oil spray to the
surface of the board. Insert it in the slot that holds the board. Mites that fall will become
stuck in the goo.
To check if the goo is thick enough, put the board in place, then smoke the colony
for several minutes. Close the colony, wait fifteen minutes, and pull out the board. The
smoke will knock a few mites off. If they are moving, you don't have enough goop. If
they aren't, you do.
After it has been on for three days remove and count the mites on the whole board.
Record the number in your notebook and remove the goo with a large, flat stick or a
spatula.
Commercial boards have a grid printed for easier counting and they fit exactly in
the screened bottom board. Peel off the protective covering, put the sticky board in the
tray in your screened bottom board, and wait the three days. During those three days
don't visit the colony. Your visit would cause mites to fall that would not normally have
fallen. Many are dislodged when you smoke a colony or move frames around. (Try this
during the summer to really see how disruptive opening a colony can be.)
This shows the bottom of a screened bottom board. The strings hold the plastic sheet of
your sticky board in place.
