CCD onset or Chilly Bees? Nosema!
The bees continue to keep me guessing. A couple of weeks ago I placed the thymol pads on my bees to knock down the mites. The bees never really enjoy this, and often engage in significant hive ventilation such that the entire hive emits the dull roar of fanning bees. Both of my hives that got the treatment were in two deep brood chambers and were occupying them well. I knew the colony in the front yard had quite a few mites, and it showed several hundred mites per day drop soon after the treatment started. But it’s the hive in the backyard that has me concerned, despite the fact that the mite drops are minimal – a few tens per day maximum.
Soon after I started treatment, I noticed a few dead bees in front of the hive. I thought that perhaps the fumes were sickening the bees so I reopened the entrance fully to give them a little more air, and watched. I wondered if the bees were chewing on the thymol pads and that was the problem, though I’ve never seen that cause problems in the past. The bee deaths didn’t really diminish much the last couple of weeks as the thymol fumes naturally dissipated. Then recently we had a spell of cool wet weather. Today was cool but sunny enough for the bees to fly, so when I went to check on them this evening, I was hoping to see a bit of activity. Instead, I found more bees than ever on the ground in front of the hive. Many of the bees had climbed up on the foliage, and a good fraction of the bees were still carrying their loads of pollen. When I examined the bees more carefully, I found that they were not dead, just very chilled. I placed a few of them in a jar, with the intent of doing some microscopic analysis. However, as soon as the bees warmed up in the jar, they became active. I took the lid off, and most of them flew back to the hive. I repeated this exercise with more, even deader looking bees, and again most of the bees revived after a little warm breath and hands on the jar.
Why would so many bees, coming back from successful foraging, just get lost at the front door to the hive? Perhaps the cool weather is playing a factor here. Bees that misjudge their landing pattern on arrival, get stuck in the weeds, quickly chill and can’t get back to the hive. But never have I seen quite so many with this problem. Could the thymol be part of the problem, or how about the fact that the colony is a bit low on stores? Could the bees be malnourished and weak? Is there some insecticide coming in that pollen? How about Nosema or a virus? Is this the beginning stages of CCD (colony collapse disorder) – whatever that is? Do the bees have some behavioral impairment so that they don’t know how cold it really is? Right now there are more questions than answers.
Update: 4/21/2011 Mystery no more. The microscope revealed that Nosema is present with a vengeance! The photo shows an abundance of Nosema spores from the gut of the first bee I examined. All the fallen bees I checked were infected. Now…what to do??
Update: 5/29/2011 After two drench treatments with Fumidal-B and a few cool spring weeks, this colony is still has dying bees in front of the hive, but it has expanded the brood nest into both full depth brood chambers and is strong with bees and brood. It’s well positioned for the coming honey flow. This hive still has very active disease but is yet a strong colony.