The "Dusk Rule"
Honey bees return to the hive at sunset. Native bees (bumblebees) often sleep under leaves.
Spraying at Dusk allows the chemical to dry overnight. By morning, it is dry and significantly less toxic to bees landing on the leaves. Beware of "Dusts" (Sevin Dust)—these stick to bee hairs like pollen and are carried back to kill the entire hive.