Yikes! Mites!

One of the problems with factory farming is that it allows pests to build up and easily transfer from one host to another. Something similar might be happening with my bees. I think that having so many hives in our Stanford bee yard may contribute to a big problem with Varroa mites.

Varroa mites attach to bees as they develop and feed on the larva. This can prevent the bee from developing properly and they also carry viruses that can destroy a hive. Here are some pictures of the mites.

Scott Bauer, USDA Agricultural Research Service, www.forestryimages.org

I did a mite count last week to determine if there are any Varroa mites in the hive, and if so, how many. The way that I do this is to put a sticky sheet of paper under the screen that serves as the floor of the hive. Occasionally, the mites will fall off of the bees and through the screen at the bottom of the hive, thus getting trapped on the sticky paper. At the end of a few days I retrieved the paper and counted the number of mites. Here are the counts:

Droogie 1: 186 mites /4 days = 47 mites/day average

Droogie 2: 35 mites /4 days = 9 mites/day average


Bad news! The levels that a hive can tolerate would be around 2-3 mites falling per day. I doubt that my colonies will be able to survive the winter with this level of infestation. After seeing this shocking number of mites in my hives, I now understand why the neighboring hives don't usually survive the winter. He uses Italian bees, which are much more susceptible to mites than my Russian strain.

So what do I do now? I really, really don't want to use any pesticides in the hive. That said, when I'm surrounded by other hives that aren't well taken care of and are mite-infested, it is almost certain that my hives will succumb to this pest.

I've decided to try an organic approach first, and measure the mite loads after I've finished. If I cannot bring the levels down, I'll try using formic acid, which has been proven to work and supposedly doesn't leave a residue behind.

The organic approach that I will take is to dust the bees with powdered sugar. Once they are covered with sugar, bees then groom each other to remove the powdered sugar and remove mites in the process. It sounds reasonable. However, there aren't any studies that show that it is effective. Based on what I've read, I have decided to dust the bees with powdered sugar 2X per week for three weeks, and will do another mite count at that time.