When to treat for mites?
Early spring and fall are the best times of the year to treat for mites. That's when we usually do not have honey supers on the hive and we have a minimum amount of capped brood.
All mite treatment options can be used at those times. Once you have a lot of brood, most treatments are not effective, or you have to make repetitive treatments to keep killing exposed (phoretic) mites.
Once you have honey supers, you are limited to honey-friendly treatments (MAQS and HopGuard).
We usually recommend treating only once a pest or disease is detected. That being said, after some more experience working with WSU Pullman bee lab, we're arriving at the conclusion that treating for mites could be advisable, even if you did not check or find mites with a test.
Last year testing of BeeManiacs yard was showing very low and even zero mite counts on most hives (based on our own testing and verified by WSU Pullman and the USDA bee lab testing).
Since we did have mites in a couple of hives last fall, we had to treat all the colonies in the same yard. During the mite treatment (we used MAQS last fall) we found dead mite drops on screened bottom trays on ALL hives (including the ones that were on zero mite test results).
It seems that mites are endemic and will be there even when our test (based on a sample of about 300 bees) finds no mites on that sample.
So, for mites, we're changing our recommendation to just treat for mites when you find it more convenient based on the status of your hive and the season.
Now is a good time.
You should not consider yourself done with mites by treating by the calendar though (once in spring and once in fall).
Keep testing and checking for mites through the season. If you have a mite population explosion at some point, you want to detect that and add a treatment at that time.
That will depend on the product being used for the treatment and the instructions should confirm that.
We can say that in most cases, colonies need to be left alone for the duration of the treatment, to make sure the treatment is effective.
In some cases, you cannot even feed the colony while they are receiving the treatment (like formic acid).
For formic acid (MAQS and Formic Pro) the supplier recommends not to inspect or disturb the colonies during treatment.