I've noticed a few of my hives, maybe 5%, have bees that are blackened. They almost look burned. Also, greasy looking. Definitely sick bees. In these hives, a frame of bees will have one or two of these on each side.
Not sure what this is.
I started using hopguard last year and also noticed the first few bees like that. Not sure if there is a connection.
Any ideas ?