Nassenheider Dispenser vs Pads
 
    I have been following the discussion between Robert Stevens and Allan
    Dick with interest.  Robert mentioned that at the ABF meeting in
    Norfolk, the Canadian(s) claimed that dispensers such as the
    Nassenheider are only suitable for the hobbyist beekeeper and not for
    the commercial operator.  I made the presentation at the ABF and I
    stated that because of the labor involved in the installation and
    maintenance of these mechanical dispensers, each occupying a frame
    space, commercial producers would not be tempted to use these devices.
 
    The pads Allan referred to have their distinct diasadvantages also. The
    application of the formic acid (FA) onto the pads or napkins/paper
    towels results in a short period of high FA concentration in the hive
    which then declines fairly rapidly over time.  Within a couple of days
    FA can often no longer be detected, and the bees chew up the towel
    material.  So, over the full course of 4 applications 5 days apart, you
    will have four high peaks in FA in the hive.  These types of
    applications can be seen as repeated 'shock treatments'.  Not very
    friendly to the bees (and the mites, of course).
 
    To minimize these major shocks to the colonies, and at the same time
    reduce the labor input component of the FA treatment, we have also been
    experimenting with larger plastic bags that are placed on the bottom
    board.  Either Ziploc (R) freezer bags or similar vegeatble bags (with
    minute holes) have been used with great success.
 
    Essentially, ziploc freezer bags (approx. 9x11") are supplied with 20 to
    30 layers of newspaper (or other suitable absorbent substrate) to which
    250 mls (approx. 8 oz.) of 65% FA is added.  All air is squeezed out and
    the bag is sealed.  When installed, two parallel cuts are made on one
    side of the bag (we use a template for the location of the cuts, but
    they are roughly at 1/4 and at 3/4 of the width of the bag).  At cool
    temperatures when the bees are more likely in the second super, the bag
    should be placed on the topbars.  With warmer weather when the bees are
    well distributed, the bag can be placed at the bottom board.  Although
    FA vapor are heavier than air, the bees aree sufficiently 'agitated' to
    ensure proper ventilation.  (A one-super colony, only one single cut
    should be made in the bag.  For 4-frame nucs, 1/2 of the amount of FA
    can be used).
 
    Some producers have reported their preference to bottomboard placement
    in the fact that the bag ends up also being a 'mite collection trap',
    offering a surface where 'knocked down' mites end up without the chance
    of recovery.
 
    After approx. 10 days, an additional parallel cut can be made in hte
    centre of the bag.  After a total 3 weeks the bag has expended all its
    FA and can be removed.
 
    The advantage of this application mthod is that we have minimized labor,
    hive manipulation, removed the peak or shock treatments, all at a very
    low cost.
 
    Because the evaporation and distribution of FA is dependent on
    temperature, beekeepers will find different levels of efficacy.  Over
    time, beekeepers will also apply modifications to the application
    methods but the above mentioned 'slow-release' method offers a great
    deal of advantages to many producers.
 
    Paul van Westendorp                         [log in to unmask]
    Provincial Apiculturist
    British Columbia