On Sun, Mar 6, 2011 at 1:58 PM, <PHutchP@aol.com> wrote:
I use a nester system from Knox Cellars for the Mason Bees I have kept for about 5 years now. The bees nest inside paper straws fitted inside cardboard tubes with a plastic end plug. The tubes lie horizontally in cans which rest inside a cedar box. I move them into an unheated garage for the winter. Normally, I remove the straws containing the hibernating bees from the cardboard guard tubes in February to get ready for the next generation. I clean the guard tubes(usually by removing debris and heating them in the oven at 250F for 20-30 minutes) and refill them with fresh, clean, paper straws. I do toss the guard tubes if they are too old or damaged.
This year, most of the guard tubes have a fungal growth on the plug end (end inside the nester can) which has digested the cardboard enough to make it soft and seems to have killed the bees on that end of the tube as well. Have you heard of this happening before? It almost seems as if moisture got trapped behind the tubes, but they are not actually wet. Then I wonder if my heating method during the cleaning process last year left viable spores that resulted in the fungal growth. The growth is white and fiberous.
I'd appreciate any information or insight you may have about this problem. It remains to be seen whether any of the bees survive as they have not yet begun emerging this year. Spring is late as my daffodils are also not yet in bloom here in Portland.
I've never seen the cardboard guard tubes rot, although the straws often have rotted holes in them. I'll assume no water is getting into the back of your tubes. I'm going to guess and say that you had an unusual number of pollen balls that either had no egg (or a sterile egg) laid in them, or the egg/larva died early. This leaves the pollen ball to be completely devoured by fungus which took part of the guard tube with it. Althernatively, a bee larva or pupa may have died after consuming the pollen ball and similarly was consumed by mold or fungus.
I would say any cocoons that look healthy should hatch and be healthy, despite the nearby presence of fungus which is ubiquitous in the environment. A nasty exception to this would be Chalkbrood which you can read about here:
[url:124ld6u8]http://www.crownbees.com/faq/troubleshooting-pests#chalkbrood[/url:124ld6u8]
tstoehr:
Thanks for the link. Perhaps the white growth and soft ends I'm seeing is the mycelium growth from chalkbrood spores as you suggest. There were a lot of dark looking dead bees in the few straws I opened.
I've cleaned the houses and put out new containers and purchased a new supply of guard tubes and straws. I've never separated the cocoons out before; just removed the straws from the guard tubes around the first of March and let the bees crawl out. Perhaps this problem is the result of that practice?
I think at this late date, opening the straws would be a danger to the bees. On the other hand, if it is chalkbrood, the spores will endanger this next generation. I'll have to have another look. I really don't want to spread such a nasty fungus. I stopped pulling out the straws when I discovered the soft guard tubes, so any spores are contained and all the bees at the plug end are likely dead from the fungus. As I said, based on what I saw in the few I opened, I'm not sure many will survive at all.
There's a difference between dead adult bees and dead larva shaped chalkbrood cadavers.
If the entire back side of the straws are moist, it's time to get rid of those straws. Many containers might not have enough overhang, and potentially aren't sloping down towards the outside.
Our products (I'm the owner of Crown Bees) are designed to drain and keep as much water out as possible.
tstoehr, thanks for the help.
Dave
Thanks, Dave. As I said, the tubes do not appear to be moist at this point, just soft with a fine fungal growth. Perhaps in the fall, before I laid the nesters away, some blowing rain got into the cans. There was no change to the way I was doing things from previous years though. The straws are changed each year and now the guard tubes are also new. I thought that heating the guard tubes in an oven would kill any pathogens that were present. That was my own addition to the process and not based on any hard science.
If I can locate your website, I'll have a look at how you are angling and recessing your nesting habitat.
Thanks again for your input.
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