I've used it with good results. 3 tsp per gallon and I spray with a fine mist until the comb looks "sweaty." One gallon goes about 12 to 14 hive bodies/supers. It's a little labor intensive as I lay out my comb in the driveway, spray it, flip it, spray the other side then put the comb back in the hive body.
I wasn't aware contamination would be an issue as Bt is species specific, harmless to others.
Grant
Jackson, MO
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