Varroa is endemic to South East Asia. We have had it here in the Philippines
forever. Our local honeybees: a. florea, a. cerana and a. dorsata seem to
have evolved some sort of "grooming" behavior, which allows them to survive
and thrive.
 
In the late seventies, after reading Dr. Morse's book on keeping a.
mellifera on the Philippines (in which he states that commercial apiculture
had many things against it here) I started keeping Italian bees. Years of
trial and error (I am NOT a scientist) have taught me to treat for varroasis
3 times:
 
1. Just before our honeyflow, which can last from 5 to 7 months (it comes in
trickles and gushes).
2. Right after pulling off all the honey from all our colonies (sorry,
Stefan, but the price difference of sugar and honey here is 1,000%!)
3. In the middle of our off season.
 
We use:
 
1. Apistan. Sorry again, Stefan, I tried herbs, aromatic trees, mothballs &
sulfur, vinegar, name it. I just need to "nuke" them sporadically. The style
here is off-timing. Regularity breeds resistance.
2. Drone brood removal. This is especiaaly useful during our very long
honeyflow. Also, we need over-abundant drones because a. mellifera is an
introduced species here and we breed in 3 separated mating yards.
3. Formic acid (careful, I've burned off my fingerprints 2 or 3 times! This
is a good tip for prospective criminals, though). You MUST have stainless
steel wires and eyelets in your frames for this.
 
It works. We are able to produce all the beehive products for our lucrative
local market. We keep a lot of a. mellifera for this corner of the world.
 
We got wiped out several times learning all of the foregoing. So, welcome to
the club everybody!
 
Joel F. Magsaysay