Ideally, pesticides should be applied when there is no wind and when bees are not visiting plants in the area. The time and intensity of bee visitation to a given crop depends on the abundance and attractiveness of the bloom. For example, apple trees or clover in bloom may be attractive to bees all day while cucumbers and corn are usually attractive in the morning and early afternoon hours. In general, evening or early night applications are the least harmful to bees. Formulation of Pesticides.
Dusts are usually more hazardous to bees than sprays.
Wettable powders often have a longer residual effect than emulsifiable concentrates. Granular pesticides seem to present very little hazard. No effective repellent has been developed that can be added to pesticides to keep bees from treated areas. Toxicity of Pesticides. Most agricultural pesticides have been tested for their toxicity to honey bees.