However, granular insecticides are less hazardous to honey bees. Residual activity of an insecticide is an important factor in determining its safety to pollinators. An insecticide which degrades within a few hours can generally be applied with minimum risk when bees are not actively foraging. Drift of spray applications can cause significant bee poisoning problems, particularly when drift reaches colonies or adjacent flowering weeds. In general, sprays should not be applied if wind speed exceeds 10 mph and favors drift toward colonies.
Temperature can have a substantial effect on the bee poisoning hazard.
If temperatures following treatment are unusually low, insecticide residues can remain toxic to bees many times longer than if normal temperatures prevail. Distance from Treated Fields. The most severely damaged colonies are usually those closest to fields where insecticides are being applied. However, during periods of pollen or nectar shortage, hives within five miles of the treated area can be injured. Time of Application.