Honey Bee Management Services

The Effect of Pesticides on Bees

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.

Preventing Pesticide Kills

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.