If you see a bunch of tiny whitish or reddish dots all over your organic material, then you likely have mites in your worm bin.

Mites aren't a problem in and of themselves (they are actually good decomposers!), but they do indicate that you may have some wetter-than-desired conditions in your bin. 

Mites generally will not attack healthy worms, but this is not always true.

To eliminate mites, add more dry bedding to sop up that excess moisture and consider dialing back your feedings by a few ounces, especially with the wet stuff like watermelon and cantaloupe.

For more guidance, please the this article!