The combination screened bottom boards have a variety of features and uses. It does not combat the varroa mites by itself. It should always be used in conjunction with another treatment such as powdered sugar and hygenic queens.
The Combo Board will facilitate most treatments available and is a complete bottom board which replaces the traditional Langstroth type bottom board.

The polyethylene hi-impact floorboard can be used in 4 ways

1. As a sticky board, for trapping varroa mites and monitoring the health of your hive. Just pour a little vegetable oil or shortening, checking to make sure it's not rancid smelling, and spread it all over the board with a paint brush or a roller. Do not use used cooking oil, it attracts  animals.  Insert the board into the lower slot, accessible from the front or rear after removing the outer door. Replace door.  

Rear access is preferable for monitoring and trapping the varroa mites. You can work the floorboard from the rear where it doesn’t upset the bees. Less need to smoke them, less chance of getting stung. We often check our boards from the rear with no veils or smoke involved at all. Remove the door and slide the plastic floorboard out.

Push board up from underneath if stuck on the center bar.
You might want to attach a string or ribbon to the hole .

Sometimes the board sags a bit in the middle. You can re-bend it (it will not break) before inserting it, or reach underneath and push the board up.

You could turn it upside down, but we are finding that oiled side picks up dirt from under the hive like a magnet. Best to bend it, oil side up.

Store plastic boards flat. on a flat surface and out of the sun.  I store extra boards outside between two outter covers.  If you leave them on an edge, the boards will sag.

Checking mites.
There are a variety of opinions concerning the 'economic threshold', that is; the number of mites you see on your board after 24 hours and its relationship to the health of the hive, or in other words, how many mites should you see before you take action. What most agree on, test the same way each time and the most accurate is to do a 3 day count during times of brood rearing, spring to fall.

Do not smoke your hives, this creates an unnatural mite drop. Insert your oiled sticky. Wait 3 day and try to remove it the same time of day. You will see a variety of debris such as wax, pollen, mature and immature mites. The mature mites are small, oval, and dark reddish brown. The immature are beige, almost transparent. Under a magnifying glass, you can see tiny feet. Count only the mature mites. We were using a random grid, but lately we draw a big cross on the board, right through the oil and debris, and then divide that area again into 4's to make counting easier. Just count one of the 4 squares. This is not scientific, just quick and easy. Take that number, multiply it 4 and then divide by the number of mites by 3 (for 3 days). We start getting concerned when we have a mite drop of 30 mites in 24 hours

Bee with Deformed Wing Virus.
Closely check your hive for bees with Deformed Wing Virus. Eric Mussen, California State Apiculturist at U.C. Davis, wrote to me in the year 2000, “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.” If you see deformed wings, take action immediately.

#2. The Combo Board works very well with Powdered Sugar Dusting.
We have been using Powdered Sugar Treatments since that spring of 2004 with incredible results and the Combo Board facilitates its use, with extra large space to pull the board out. This prevents scraping sugar and mites to the ground and messing up your samples.

#3. Remove the board entirely.

Beekeepers all over the world have been removing their bottom boards and allowing the mites to fall to the ground with wonderful results of not having to medicate. Having no solid board again brings many opinions. 

  There is a study from Canada by Jean Pierre Chapleau, 'Les Reines Chapleau', where they found open bottom boards in cooler wet areas actually increased the varroa mite population to almost double due to the cooler conditions delaying the hatching of brood and allowing the mites to reproduce again in the capped cells during those few extra hours. The report also said there was a great success with hives kept in warmer, dryer areas of country. We give you that option.

#4. Using the floorboard as a traditional solid floor. (This will not trap mites).
Slide the plastic board on top of the screen, from the front entrance.
Keep a weak hive warmer.
When using a fume type product like thymol, oxalic or formic, sliding the board on top of the screen, will keep the fumes in the hive and will protect the metal screen.