>
> "Fumidil-B is best prepared at a concentration in the range
> of 75 to 100 mg.fumigillin activity per gallon of 2:1 sugar
> syrup."
>
> So far so good!
>
> The instructions now leave the confines of reality
> as they further recommend," When only (1) or (2) colonies
> are to be treated, the syrup may be made by dissolving a
> rounded teaspoonful (3.75 to 5 grams ) FUMIDIL-B per galon
> of syrup."
 
When 5 grams of FUMIDIL-B is used to a gallon , this amount  is only 20%
of the bottle contents of 25 g,  and will only contain  0.1 grams (=100
mg) of fumagillin. This is exactly the same dose as you get in using the
bottle of 25 g (with 500 mg of fumagillin) to 5 gallons.
 
 
> At the 5 gram/gal. rate, you are overdosing your bees
> by a factor of 10 to 1.
>
 
No, you are not; Fumidil-B is not only fumagillin
but also some other stuffs needed for the preparation.