Blister/bump

[RegotBee]

I recently found a colony of feral bees in a fallen tree near some of my hives. As I looked closely at the bees around the entrance, I noticed that several had a relatively large (0.5-1 mm) blister-like bump on the thorax.

What are the most likely causes of such a deformity? Do I need to worry about my bees having been exposed?

[tarheit]

Was this bump reddish in color? It might be varroa.

Compare it with the picture at: http://www.kohala.net/bees/varroa.html

If it is varroa, then it definately could be a problem for your hives. Bees will drift (or rob) carrying the mites to your hive.

[RegotBee]

Bingo! Thanks for the link, tarheit; that is it, exactly.

It appears that I have had my first encounter with the Dread Varroa mite. I really had no idea they were so large. I always pictured them as almost microscopic, but there was no mistaking the presence of these monsters.

The property owner has had the feral bees destroyed, so that is at least a comfort, but I will definitely keep a close eye on my hives from now on.

Thanks again for the help!

[Michael Bush]

Once you see them, varroa mites aren't hard to spot, but many people have serious infestations and never see them.

[Alfred]

Put some (2 or 3) Oxamite strips in your hive this will help a lot, many mites coming in contact with the substances from the strips and die.
I have strips in my colonies for several week and there is a continue mite fall I never had before. There must be suffering colonies in my neighborhood.
I think this is better than a sugar roll test to find out whether colonies are infected or not