> > Dave Green wrote: > > > When the spraying is done at night, or at least after the > > bees are done flying, there is no real hazard to the bees. > > > By morning the dew has broken down the non-residual > > pesticide and it is no longer toxic. > Robert Post responded: > Three problems with these comments: > > Firstly not all agro-chemicals are broken down over an eight hour periodk. > > Secondly the break-down period of eight hours is normally extended because of the > moist and cool conditions of evening. > > Thirdly many agro-chemicals (or cocktails thereof) contain substances that induce > a repellency action. Robert, Dave Green was talking about the impact of Sumithrin insecticide when sprayed for mosquito control. In my opinion, the scientific literature on mosquito spraying supports Dave's comments for the following reasons: a) Sumithrin, like resmethrin, is one of the 30 year old, first generation pyrethroids that has virtually no residual activity or lasting repellency effect when applied outdoors. b) The dosage of sumithrin or resmethrin used for mosquito spraying is extremely small (around 1 ounce per acre = 5 gallons per square mile). This further reduces the chances of any residual or repellency effects interfering with bee activity. c) Petroleum or vegetable oil (not water) is used as a carrier when applying mosquito adulticides like sumithrin & resmethrin, in part, because they would more rapidly break down if mixed with water. d) Like Dave says, because the mosquito spraying is done at dusk or at night, when the bees are not flying, there is no real hazard to the bees. Paul Cherubini