Would it be advisable to fog a colony that is weak? They have a queen and are raising brood, but there are not alot of bees. They were a late caught swarm and never really got a chance to build up before winter. They did have some might fall in the fall and I treated them with cords. I'm wondering if I should wait till they are more built up, or fog now, the first warm day I get?
From my experience, FGMO is an ongoing treatment that kills some mites every treatment. If you use it regularly you can control the mites.
If you want a dramatic change in the mites, I'd use the thymol with it (which I haven't tried) or the oxalic acid. Just FGMO by itself all the time works, but not dramatically.
Chances are neither is going to rescue an already weak colony, but neither is going to do any harm either.
I'm mainly worried about wether fogging will put them over the edge. I think if I knew what I know now ,I would have combined this colony with another last fall. I'm just trying to figure out if the added stress of treatment is better than the added stress of mites?
When you fog them or when you use the oxalic acid, they bees do not get upset at all (other than a couple of gaurd bees wrestling sometimes) and I have noticed no increase in dead bees. I do not see any noticable evidence that either one stresses out the bees. As I said, I have not tried the thymol so I can't say if it upsets them or not.