Testing for Mite Load
Testing determines what percentage of bees in your hive have varroa mites on them. A mite load of zero is ideal, but anything under one percent is acceptable.
In our region, we recommend testing monthly from March through October, with additional testing as needed.
Treatment recommendations vary, but most experts suggest treating when your mite load approaches or exceeds three percent.
There are multiple testing methods. The alcohol wash is considered the gold standard, but it kills the 300 bees used in your test. Alternatives include the powdered sugar shake, which does not kill them.
Bottom board counts may confirm the presence of varroa in a hive, but they are not as accurate as the alcohol wash. Do not rely upon them to gauge the extent of an infestation.
This in-depth video produced by the University of Guelph Honey Bee Research Centre in Canada shows how to conduct an alcohol wash and discusses when and how often to conduct one. This is a good video for someone who is new to using an alcohol washing to quantify the extent of a varroa infection.
A quick and casual video of how Randy Oliver of ScientificBeekeeping.com does an alcohol wash. It makes an interesting comparison to the video above and shows how rapidly you can test a single hive.
Sugar Roll or Sugar Shake
This video from Louisiana State University reviews how to use a powdered sugar roll, sometimes known as a sugar shake, as an alternative to alcohol wash.