Bob,
I have had the exact opposite results from the use of menthol, miticur 
(amitraz), and Apistan (fluvalinate) than what you have said in your note.

One of the MOST criteria in the use of any miticide is the TEMPERATURE at the 
time of use.  Frankly, the largest majority of beekeepers have just IGNORED 
the directions indicated by the manufacturer or the scientists who did the 
research on the chemical.  They have ignored it for several reasons: did not 
think it was that important, interfered with a nectar flow, placed the 
product in the hive in the wrong location, interfered with the beekeeper's 
vacation time, or did not take proper care of the left over product that they 
were going to use the following year, and finally, treated at a time 
CONVENIENT to the beekeeper and NOT the best time to
kill the mites.

You mentioned that your area is too cool for menthol use.  Your area near 
Kansas City is SOUTH of my home just outside of Washington, DC.  Menthol must 
be used in weather that is warm enough to make it sublime (turn to gas 
directly from solid without becoming a liquid).  The sublimation point of 
menthol is 84° and the fumes must be present for at least 3 weeks to be 
breathed by all the bees and unemerged
brood in a colony in order to KILL tracheal mites.  In my area of central 
Maryland, menthol MUST be installed BEFORE September 1st to be effective, and 
August 15th
is the day that I suggest to by "students"; and your area should be 
identical.  Those who have installed menthol in September or October have no 
right to complain that "menthol does not work," because it could not work at 
temperature less than 84°.
Some of these people might say that they still have supers in place in August 
and can't use menthol until later.  They have a choice: remove the supers and 
treat in August to save the bees and not make as much honey, or treat in 
September or October and lose their bees to tracheal mites in December or 
January, or switch to labor intensive use of grease patties from June to 
December and replacing those patties in the brood chamber every 2-3 weeks for 
6 months.  Tracheal mites are NEVER in brood bees, but only live in adult 
bees, and these adult bees die of strangulation from mites in their 
"breathing tubes" when there are no new bees to take their place.

The Varroa mite is the EXACT opposite of the tracheal mite.  Since the ONLY 
place that a female tracheal mite lays new mite eggs is in a bee larva cell 
about one day before that bee cell is capped, it is obvious that the best 
time to get the greatest kill of Varroa mites is when there is LITTLE or NO 
bee brood present for the female mite to lay eggs.  When is that period in 
your area?  In central Maryland, the queen bee slows down her egg laying 
dramatically beginning in September and quits completely about November 15th 
or Thanksgiving.  Hence the very best kill of Varroa mites that you can get 
is to install Apistan strips on October 1st and leave them in the colony for 
a minimum of 6 weeks (about November 15th) and REMOVE them the first day 
after Nov. 15th that the temperature hits 50°, when you will not break a 
cluster by opening a colony.

I am certainly not going to say that there aren't some parts of the country 
that
Varroa mites have become resistant to Apistan, because overuse of Apistan plus
LEAVING IN THE COLONY ALL WINTER have surely increased the resistance.  
However,
it has been found by researchers, inspectors, and scientists that the 
locations
of truly resistant mites are few and far between.  So often, in fact many 
times, the Apistan strips have NOT BEEN PROPERLY CARED FOR before they are 
used and their
potency is GONE.  The chemical fluvalinate is destroyed by LIGHT, aging, too 
much ventilation, and excessive temperatures.  Yet, beekeepers open a package 
of Apistan,
remove a strip or two, and leave the remainder of the package open to the 
light, wind, and high temperatures in the back of their pickup truck.  The 
Apistan strip
loses its potency and the beekeeper loses bee colonies, and then claims that 
the mites have become resistant to Apistan.  Horsefeathers!  The carelessness 
of the beekeeper (who did not read all of the directions on the use of 
Apistan) caused his loss of bees.

Miticur was a fine product that worked well, and still works wonderfully in 
Europe.
Some commercial beekeepers discovered that certain veterinarian products 
contained a higher percentage of AMITRAZ than mitcur strips and was also 
cheaper; so they bought the product to treat their bees for Varroa.  
Thousands of colonies died, and these unscrupulous beekeepers had the gall to 
enter suit against the Hoffman-LaRoche Co., the manufacturer of Miticur.  
Rather than hire expensive
lawyers and spend time in court, Hoffman-LaRoche simply withdrew all Miticur 
from production.  Again, beekeepers fault, and not the fault of the product.

When the speed limit sign says 65 mph, and a person gets killed when he is 
driving
80 mph, does his family have the right to claim that the curve in the road 
was too sharp?  There would be so many less so-called beekeeping problems if 
beekeepers
would just read ALL the directions and FOLLOW them, plus learn some bee 
biology
so they are better able to understand the problems of their "girls"

As you know, I am not some hobbyist who has had 3-4 colonies for a few years. 
 Until I became disabled by severe strokes in 1996 and 97 that caused me to 
cut back to just 20 colonies, I have kept 100-150 colonies for most of the 68 
years that
I have been keeping bees.

I will end this long diatribe by saying "you can't keep bees like Daddy kept 
bees!"
Daddy did not have mites, Africanized bees, public fear of bees, resistant 
AFB,
viruses or imported honey.

I hope that I have helped.

George Imirie