In the CO2 method, bees and mites are rendered unconscious by exposure to carbon dioxide gas. The sample of anesthetized bees is then gently shaken in the EasyCheck, causing the mites to fall from the bees and pass through the white basket’s holes. Research conducted in Europe indicates results that are similar in accuracy to those obtained by an alcohol wash.*
*Efficiency of Varroa monitoring methods, the benefits of standardized monitoring devices.
Ludovic de Feraudy, Dr. Ulrike Marsky & Ph.D Jiri Danihlik. - Apimondia 2019 proceeding.
How to perform a CO2 injection for mite monitoring?
Required material (not included): CO2 injector/dispenser (to purchase separately) with a CO2 cartridge.
Collect a sample of 200 or 300 bees with the white basket, preferably from a frame of capped brood (make sure the queen is not in the sample). The marks for 200 and 300 bees are indicated inside the basket. Put the basket back UPSIDE-DOWN into the transparent bowl and push it until it's correctly seated inside the bowl (it should stay in place if you turn it over).
Place the yellow lid on the top. Create a small opening between the yellow lid and the transparent container and inject the CO2 through the holes of the white basket for 5 to 6 seconds, until the bees stop flying. Do not inject directly toward the bees. Then, quickly screw the lid. Let the Varroa EasyCheck sit for about 10 seconds, until the bees are anesthetized.
Turn the Varroa EasyCheck upside-down and gently shake the sample for 15 seconds, so you do not hurt the bees. Varroa mites will be dislodged from bees and fall through the holes of the basket.
Open the yellow lid and count the mites inside. Calculate infestation rate per 100 bees, as for alcohol wash. Depending on if you took 200 or 300 bees divide the number of counted mites by 2 or 3 to get your infestation rate (%). To interpret the results, please consult our Varroa Guide and/or your local thresholds.
Put the bees back in the hive where they will recover. Dispose of the fallen varroa mites, as most will still be alive.