I wrote:
>Compare: 69% infestation rate with screens, 70% without. The screens seem to double the effectiveness of formic acid, but you could get the same rate by doubling the dose of formic.

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.


Dave wrote:

> The IPM figures that you quoted, seem to have been selected for their lowness of effect, which is hardly good science. I have seen various figures bandied about, but if you count the mites that fall you will find that about 65% of them are alive and the rest dead I would much sooner lose the live ones for good, regardless of percentage.

I did not "select" these figures for lowness, but rather, I couldn't find any others. If you have any published figures, I would be interested in seeing them. Finding live mites on the bottom does not necessarily translate to reduced mite load in the colony, especially if the mites are past the reproductive age. By the way, in order for a technique to be included in a real IPM program, it has to have some repeatable effect -- and it has to be cost-effective.