Pesticides are substances used to eliminate unwanted pests. Insecticides rid us of unwanted insects. Unfortunately, honey bees are insects and are greatly affected by insecticides.
There are several ways honey bees can be killed by insecticides. One is direct contact of the insecticide on the bee while it is foraging in the field. The bee immediately dies and does not return to the hive. In this case the queen, brood and nurse bees are not contaminated and the colony survives. The second more deadly way is when the bee comes in contact with an insecticide and transports it back to the colony, either as contaminated pollen or nectar or on its body.
The main symptom of honey bee pesticide kill is large numbers of dead bees in front of the hives. Another symptom is a sudden loss of the colony’s field force. After a honey bee pesticide loss the colony may suffer additionally from brood diseases and chilled brood.
Many pesticides are extremely toxic to honey bees and other beneficial insects. Honey bees are attracted to blooming flowers of all types. If at all possible do not spray blooms directly with pesticides. If the bloom needs to be sprayed, apply the pesticides in the evening hours. Honey bees forage during daylight hours when the temperatures are above 55-60°F. As the sun begins to set, they return to their hives for the evening. Thus, spraying pesticides in the evening hours can greatly reduce honey bee mortality because the bees are not in the fields.
Aerial applications have the highest potential risk for causing bee kills. Most bee kills occur when the pesticide drifts or moves from the target area into the apiary or onto crops attractive to the bees. The outcome of drift can be catastrophic. Spraying during windy days greatly increases the risk of drift. Using granular formulations, soil treatments or equipment that confines the spray to the intended target can help reduce the risk of drift from pesticides.