Prevent Bee Poisoning

Bees are essential for the pollination of most trees, small fruits and flowering field crops. Insecticides, many of which kill bees, are required for insect control but with careful management, both pollination and insect control can be achieved. Both growers and beekeepers should be in good communication to avoid application of pesticides that may impact honey bees.

For Growers and Applicators:

Do not apply insecticides while fruit trees are in bloom. The Bees Act makes it an offence to do so in Ontario. Do not spray any flowering crop on which bees are foraging and read the pesticide label for guidelines. On some pesticide labels, it is illegal to spray during bee activity or daylight hours. Both the Pest Management Regulatory Agency (PMRA) and the Ministry of the Environment (MOE) can address any misuse of pesticide products. See contacts below.

Time insecticide applications to minimize bee poisoning. Daytime treatments, when bees are foraging, are most hazardous. Insecticide applications in the evening are the safest. Spraying after 7 p.m. allows the spray to dry before the bees are exposed to it the next day. This is the most successful way to avoid bee damage. Early morning is the next best time, but spraying should be completed before 7 a.m. Bees do not usually forage at temperatures below 13°C. If you plan to spray in the morning, contact beekeepers with bees within 10 km of your crop. The beekeepers will then have the option of taking protective action.

Do not apply insecticide on windy days to prevent drift toward any nearby hives.

If there is a risk of honeybee poisoning, try to choose an insecticide that is not highly toxic to the bees from the list in Table 11-3. Relative Toxicity of Pesticides to Honeybees. When there is a choice, choose a product formulation that is less hazardous to bees. EC formulations are less toxic than WP formulations.

See Link for relative toxicity to honey bees:

Honeybees are frequently poisoned by visiting weeds or cover crops, such as dandelions or clovers that are in bloom in the orchard or field. Clip or beat down such crops prior to a spray to help safeguard the bees.

Before applying a pesticide, advise local beekeepers so they can move colonies out of the danger area. Contact the Provincial Apiarist at 1-888-466-2372 ext. 6-3595 for a list of the beekeepers in the area or see and click "Apiculture" for a list of provincial bee inspectors who know the local beekeepers.


Beekeepers can place wet bags in the entrance of the hive to disrupt the flight of the bees for up to 12 hours and provide more time for spray to dry. An opening of 2.5 cm (1 inch) on each side of the hive entrance is necessary so the bees can get out and ventilate the hive.

Beekeepers should remove honeybee colonies as soon as pollination is complete and before any postbloom insecticides are applied.

Table 10- 6.

Relative Toxicity of Insecticides to Honeybees

Product(s) Active Name
Admire imidacloprid
Agri-Mek 1.9EC abamectin
Cygon 480AG; Lagon 480E dimethoate
Ripcord 400EC cypermethrin
Decis 5EC deltamethrin
Diazinon 500 E, Diazinon 50W, DZN 600 EW diazinon
Dibrom naled
Furadan 480F carbofuran
Imidan 50WP phosmet
Lannate methomyl
Lorsban 15 G, Lorsban 4 E, Lorsban 50W, Pyrifos 15 G, Pyrifos 50 W, Pyrinex 480 EC chlorpyrifos
Malathion 25W, Malathion 500 E malathion
Matador 120EC cyhalothrin-lambda
Monitor methamidophos
Orthene acephate
Pounce permethrin
Pyramite pyridaben
Ripcord 400 EC cypermethrin
Sevin XLR carbaryl
Success 480SC spinosad
Vydate L oxamyl

Moderately Toxic Apply only during late evenings or early mornings.

Product(s) Active Name
Assail 70WP acetamiprid
Endosulfan 50W; Thiodan 4EC; Thiodan 50WP; Thionex 50WP endosulfan
Pirimor 50DF pirimicarb
Supra Captan 80 WDG, Maestro 80 DF captan

Read each pesticide label for specific precautions regarding bees.


Contacts for the Pest Management Regulatory Agency (PMRA):

for Grey , Bruce & Ontario West:
Paul Mailloux
1200 Commissioners Road East Unit 19
London, Ontario, N5Z 4R3
tel #: 519-691-1306 ext 127

for central Ontario (except Toronto & Toronto north) :
Unit # 109-255 Woodlawn Road West
Guelph ON N1H 8J1
tel #: Diana Ball 519-826-2827
tel #: Murray Stevenson 519-826-2916
tel #: Cathy Nederend 519-826-2886

for Toronto & Toronto north ;
180 Queen Street West
Toronto, Ontario M5V 3L7
tel #: Bert Doobay 416-954-3745
tel #: Linda McIntosh 416-952-7101

Ontario East :
2720 Riverside Drive
Ottawa, Ontario K1A 0K9
tel #: David Quesnel 613-736-3490

as well, National Pesticides Call Line Service @ 1-800-267-6315

Contacts for the Ministry of the Environment (MOE):

For more information:
Toll Free: 1-877-424-1300