It is important for beekeepers in Ontario to understand the signs of poisoning and the process for reporting in the event of a possible exposure and/or subsequent bee kill.
Symptoms of acute pesticide poisoning of honey bees may be much easier to recognize than chronic symptoms. Provincial Apiarist, Paul Kozak provides the following list of symptoms for most types of insecticides, although he cautions that some particular classes of insecticides may have distinct symptoms.
Pesticide damage may take place at an individual or colony level. The impact of pesticide poisoning to a colony may be short-lived or longer lasting. Longer lasting may result from multiple pesticide applications to the same or different fields or when contaminated pollen is brought back to the colony and contaminates food stores.
Symptoms of Acute Poisoning at the Colony Level:
Excessive numbers of dying and dead bees in front of the hive, on the bottom board or on top bars. This can take place within 24 hours of exposure.
Dead bees at the entrance may represent only 10 – 20% of the total number being killed as more bees might die in the field.
A sudden pronounced decrease in colony population (thousands of bees) in a previously strong colony in the middle of the spring or summer season. The colony may stop growing in population during a time of the season where they should be normally increasing.
Brood may become chilled within days or weeks due to insufficient workers to maintain and care for the brood.
Dead larvae, being pulled out of the cells.
Sudden aggressive behaviour in the colony, queen supesedure, repeated queen failures.
Symptoms of Acute Poisoning in Individual Honey Bees:
Paralysis, trembling, stupefaction, disorientation and erratic behaviours by worker bees.
Honey bees regurgitating, sometimes where many dead and dying bees form a wet, sticky mass.
Loss of hairs: bees appear dark.
The presence of only young (fuzzy looking) bees, indicating a major loss of older foragers.
Sub-Lethal Effects at the Colony Level:
Decrease in population, lack of colony development.
Queen health issues, such as a spotty brood pattern.
Dead larvae are dried out.
We encourage all beekeepers to report even suspected chronic or acute bee poisonings as soon as possible. Please let the OBA know if you report a bee kill. firstname.lastname@example.org
Pesticide Reporting Contact information:
National Pesticides Call Line Service: 1-800-267-6315