Avoid applying pesticides when bees are active in your yard. When bees come in contact with pesticide residue, both the insect and the pollen become contaminated. Worker bees return to the hive carrying loads of nectar and pollen from insecticide-treated flowers and share it with other workers, larvae and even the queen. Exposure to insecticidal products can kill them.
Nectar, the sweet liquid produced by many flowers, is the major food source for bees and the raw material used to make honey. Bees pick up sub-lethal doses of insecticide in nectar and return to the hive. When water is removed from the nectar and then served to the inhabitants of the hive, the doses of insecticide are increased to lethal concentrations.
Bees are an essential part of our ecosystem. They provide pollination to many fruit and vegetable plants. Insecticides applied as sprays or dusts represent the biggest threats to bee populations. Many commonly used insecticides like Sevin, Malathion, Permethrin and Orthene are hazardous to bees and can remain toxic for several days after application. There are relatively non-hazardous insecticides available. They include Pyrethrum, Azadirachtin (Neem oil) and insecticidal soaps that rapidly break down by exposure to sunlight and microbes.
By following a few simple steps, you reduce the threat to bees when applying pesticides. Apply chemicals late in the day when bees are not foraging. Use chemicals with low toxicity or those that are less persistent. Avoid spraying open flowers. Apply insecticides when there is no wind. Spray only when the target insects are active.