When I had my little EFB outbreak last spring it was borne in on me the fundamental difference between the two brood diseases: EFB is a disease of the larval stage and AFB is a disease of the pupal stage. Before that, this point was somehow unclear to me.  It was a useful thing to learn, however, as it sharpened my observational and diagnostic skills.  

But later on, several knowledgeable people mentioned to me that I was looking at a spring/early summer EFB infection, and that if it had persisted or re-occurred in the fall it might look somewhat different, tending to affect more of the pupal cells than in the spring.  Perhaps the disease expression in the Fall is different due to a later-in-the-larval-stage infection which only manifests itself after capping, or some other difference (concomitant infection with mites, or seasonal nutritional differences such as more pollen being available than in spring).  I just don't know.

I wasn't really looking forward to chance to see a late-season EFB manifestation last year, and happily after I treated with Oxytet starting in late June, things cleared up promptly and there was nothing to see in the fall. But I confess I am dreading the start of a new season because I fear I may have to deal with another round of it this spring.  EFB makes me feel like a very bad beekeeper.

Nancy

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