To join our club see the Membership section!

Typicallly we meet the 3rd Wednesday of the month 7-10pm from spring to fall.

See the meeting section for details

Approximately 60 people attended and were treated to a great presentation by Tim and Kristina Greer at our March 2023 meeting.

October 16, 2023Possible Apivar Resistance Identified In Ontario

The OBA Technology Transfer Program (TTP) received some funding to do small scale and local sampling of several hives in several apiaries near Guelph in September. The goal was to identify if resistance to Amitraz, the active ingredient in Apivar, was developing in Ontario. The results of this testing have recently become available and may be important to consider in our fall and spring mite management plans. The results are preliminary and from a small sample of apiaries. Despite the limited scope of the project it was considered important to share these preliminary results while beekeepers using Apivar may still be able to do mite counts to confirm treatment efficacy in their own apiaries prior to the winter.

Varroa mites can develop acaricide resistance because of repeated or over/under-exposure to chemical treatments. A Pettis test is one of the methods used to test mites for resistance. A Pettis test involves exposing a sample of mite-infested bees to a small piece of a chemical strip. The bees are placed in glass jars and exposed to the strips for 24 hours. After the test period is complete, the efficacy of the chemical strip is estimated by comparing the number of mites that fell during the 24 hour test period (mites that were killed by the strip) to the total number of mites in the test jar (mites that were killed by the strip + mites on the bees that were not killed by the strip).

The Pettis test also involves comparison to a control. Control jars were tested in the same way, but the bees in each control jar were not exposed to any chemical strip. Control mortality should be low; high control mortality could indicate that the mites being tested in the treatment jars were dying of causes other than exposure to the acaricide. This could potentially obscure the data and hide possible resistance. When control mortality levels are high for particular samples, the chemical efficacy values for those samples should be taken with caution.

For the Pettis test to be reliable, a high infestation of mites is required. Colonies to be tested for resistance were pre-screened with an alcohol wash. Only colonies with a mite infestation of 3% (3 mites / 100 bees) or higher were tested for resistance. In addition, colonies could not have been treated already with the particular acaricides being tested. For this test, colonies were screened for resistance to Amitraz, the active chemical in Apivar.

The exact cut-off for resistance is not consistent across all sources. A population of mites is generally considered resistant to the chemical strip if the efficacy is below 75%. However, some sources use a higher cut-off of below 85%. Alberta uses a cutoff of 25% to determine if Apivar resistance exists.

The surveillance testing of Varroa mite populations for resistance to Amitraz was funded by the Ontario Animal Health Network (OAHN). TTP performed the Pettis test on 28 colonies distributed across 9 beeyards, primarily located in the Guelph-Wellington region. Through this testing, TTP detected Varroa mites in two distinct beeyards that showed less than 85% mortality after exposure to Amitraz. Varroa mites from one colony showed 66.75% mortality, while Varroa mites from the second colony showed 77.95% mortality. These results indicate that there are Varroa populations present in Ontario against which Amitraz has low efficacy. Furthermore, these results demonstrate a need for further surveillance, with a broader scope as well as genotypic testing to confirm the presence and prevalence of Amitraz resistant Varroa populations in Ontario.

These results are consistent with reports from several Ontario beekeepers who have reported that they have seen Apivar efficacy decreasing in their operations in recent years. Other Ontario beekeepers have continued to observe high efficacy to Apivar over the same time period. Apivar resistance has been reported in the US and Alberta.

Attempts are being made to carry out sampling and testing from additional apiaries over a broader geography in Ontario to validate the findings of this initial small scale surveillance sampling. Because of the requirement that colonies not be treated already, it remains to be seen whether this falls’ sampling will garner enough eligible yards and hives to support these initial results.

Ontario beekeepers who are currently using Apivar for mite control or plan to use it in the coming years are strongly encouraged to assess the mite loads in their colonies. Beekeepers who find high mite counts in colonies that are being treated with Apivar or have recently been treated with Apivar may want to consider using a follow-up treatment with a different product to make sure that their mite levels are low prior to winter. Information on registered mite treatments and the conditions (i.e. temperature) in which they can be used are available on the OMAFRA website.

Please reach out with any questions or concerns.


Melanie, on behalf of the OBA Board of Directors

Ontario Beekeepers’ Association5420 Hwy 6 N, Suite 185

Guelph, ON N1H 6J2
Phone (905) 636-0661

OMAFRA Overwinter Loss Survey 2022-2023

June 16, 2023 message from Paul Kozak, Provincial Apiarist:

This is a friendly reminder that the Ontario Ministry of Agriculture, Food and Rural Affairs’ (OMAFRA) 2022/2023 Overwinter Loss Survey for Ontario beekeepers is open for response until June 26, 2023.

The survey is online and you can directly access the survey using the link provided above and below. Responses collected through this survey are kept anonymous and provide important statistics on the estimated mortality of Ontario’s managed honey bee population as well as key management practices used by beekeepers to control pest and disease issues. 

As of June 14, 2023, only 11% of Ontario beekeepers have responded. This is a very slow start, so we would like to see this number grow! Please take a few minutes and complete the survey before the June 26th deadline. If you have already completed the survey, THANK YOU! If not, the ministry is keen on hearing from you in light of last year’s higher than normal colony losses. It is important that Ontario has a robust response rate to better understand the status of bee health in the province.

As a reminder, the OBA Winterloss Survey, administered by the Ontario Beekeepers’ Association earlier this spring, is conducted independently of this survey as is OMAFRA’s in-season mortality report which is an online tool you can use to report a significant honey bee mortality incident experienced either during the active beekeeping season or over the past winter.

The 2022/2023 Overwinter Loss Survey provides the official winter loss statistic for Ontario and is reported to the Canadian Association of Professional Apiculturists.

If you have questions about the completion of this survey, contact the Apiary Program by email at or by phone, toll free, at 1-877-424-1300.

OMAFRA Overwinter Loss Survey 2021-2022

May 20, 2022 from Paul Kozak, Provincial Apiarist:

As you may be aware, there have been early reports of high honey bee colony losses in Ontario and across Canada over the past winter. To better understand Ontario’s overwinter losses, I ask that you please take the time to complete the 2021/2022 Ontario Overwinter Loss Survey administered by the Ontario Ministry of Agriculture, Food and Rural Affairs. 

Like last year, the survey will be administered online and will remain open for responses until June 19, 2022. The responses collected through this survey will be kept anonymous and provide important statistics on the estimated mortality of Ontario’s managed honey bee population as well as key management practices used by beekeepers to control pest and disease issues. 

If you have any questions about the completion of this survey, contact the Apiary Program by email at or by phone toll free at 1-877-424-1300.


The Following was an email sent to the Sudbury & District Beekeepers Association

“I received the following information from Kathie Hogan, the Powassan Beekeepers’ group. This is to inform all local beekeepers that AFB (American Foul Brood) is present in the Nipissing District. An apiary located in Corbeil off of Centenniel Cres. was confirmed to have AFB today in 2 of its 5 hives, with possible symptoms in the other 3 hives. As resources have been shared between hives within the same yard and the similarity in symptoms the beekeeper has chosen to move forward with the burning of all 5 hives in the coming days. These bees have been treated regularly in spring and fall and monitored every 7-10 days. No used equipment or bees or sharing of equipment with other beekeepers or beeyards. The beekeeper noticed during the last check brood concern and contacted the local Ontario Bee Inspector who visited the site today, August 13th and confirmed the presence of AFB. It appears to have been contracted naturally through bee movement. This is a really serious situation. PLEASE check your own hives in the days ahead. Here is what to look for-…/inspection/bees/afb-mgmt.htm

If you suspect AFB, please contact the local bee inspector immediately.



The only guaranteed solution, once detected, to stop the spread of American Foul Brood is to burn your hives. This is mandated under the Bee Act of Ontario (

Please read the Bee Act and be familiar with it. Beekeeping can be wonderful, but there is definitely a serious side to it.”