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