How to identify & report suspected pesticide poisoning incidents.

We are quickly coming up to what could be our third season of significant bee kllls related to pesticide poisoning. While we are hoping that the measures grain farmers and others have put into place will have some impact, we want beekeepers in Ontario to understand the signs of poisoning and the process for reporting in the event of exposure.

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 into the food stores.

Symptoms of acute poisoning in individual honey bees:According to Paul, symptoms include:

Paralysis, trembling, stupefaction, disorientation and jerky, 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.

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 or  days or weeks. Dead bees at the entrance may represent only 10 - 20% of the total number being killed as most bees are in the field.
Sudden pronounced decrease in colonypopulation (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 4 to 8 weeks due to insufficient worker to maintain and care for the brood.
Dying larvae crawling of the the cells.
Sudden aggressive behaviour in the colony.
queen super secure, particularly multiple supersedures.
Subtle Effects at the Colony Level:
Decrease in population, lack of colony development
Queen health issues, such as a spotty brood pattern.
Dead larvae are dry.

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 but PMRA is not able to respond.

Contact information:
Linda McIntosh, Regional Manager,
Pesticide Compliance Program,