Peter wrote:
>
> Unfortunately, this is an example of faulty math. If screens with
> formic have half as many mites, that doesn't mean double
> effectiveness, my mistake.
>
> Actually, if the controls are 70% infected and the formic hives
> have a 21% rate, then 70% of the total mites  have been killed
> (49 divided by 70). If you add the screens and have a 9% rate,
> then you have killed 87% of the total mites (61 divided by 70).
> This means that only 17% of the total kill with formic and
> screens combined is accountable to the screens.

That doesn't sounds very impressive put that way, but comparing the
resulting infestation rates with and without screens (21% and 9%) it seems
that the screens got rid of more than half of what the acid alone left
behind, lowering the infection percentage (measured how?) by about 57%.
Perhaps the formic acid treatment results in mites which fall but are not
killed, and the screens remove most or many of those from the hive.

Frank.
-----
The very act of seeking sets something in motion to meet us;
something in the universe, or in the unconscious responds as if
to an invitation.  - Jean Shinoda Bolen