Sterilizing Nesting Material

Is there some way out there that can safely be used to sterilize nesting sites/blocks? Most recommend paper or cardboard tubes but are those really a sustainable way of doing this? Looking for natural methods that can be sustained even if commercial systems fail including the electrical systems.

Just found one suggestion in this article

http://www.xerces.org/wp-content/uploads/2009/11/tunnel-nest-management-xerces-society.pdf

but did not sound like it was completely effective.

What is the length of viability of chalkbrood spores anyway?

some folks use teasel or reed stems with good results. tossing those out every year shouldn't be so unpleasant as a manufactured tube.

In germany exists a method to raise the Red Mason Bee (Osmia rufa) in wooden stacks. Basically the nesting tubes are replaced with 15mm thick wooden boards, in which grooves of 8mm depth are running in parrallel (distance 10 mm). Theese boards (16x16 cm) are stacked, so that each groove is closed with the flat side of the next board. Every 20 boards or so are tied together to form a block with 200 nesting tubes. If you need to clean the boards (or want to harvest the cocoons), you can untie the stack. As the grooves are open, it is pretty easy to savely remove the cocoons and clean the boards. You could use a hot air gun (after mechanical cleaning), you could heat theese boards to a minimum of 50°C for some hours, or cool them down to -70°C (the last beeing not practical unless you have easy access to liquid nitrogen)

It is most imortant, according to the orinial authors, to keep the nesting boards clean to prevent against pests. This means you remove old pollen and dirt with a strong brush to prepare the boards for each nesting season. The authors remove the bee cocoons from the boards systematicaly, to clean the boards and remove fly larvae and other pests.

For those who can read german, here is a link to the method: http://www.bienenhotel.de/Handbuch_der_Mauerbienenzucht.pdf

Steve,
I started making and using Mason bee blocks many years ago. When I started we didn't even know there was all these problems about sterilizing nesting blocks. In years gone by, the holes in the blocks would become restricted from use and reuse season to season. The bees would then stop using the holes they couldn't get into. We just installed new drilled blocks next to the older ones and took down the old "worn out" blocks that the bees didn't use. When these sterilizing issues surfaced I decided to experiment with those old blocks - I took the abandoned blocks down, ran a drill bit through each hole to clean them out, put the block in the microwave for a couple minutes, (make sure there is no metal, i.e. nails in the block) and put them back up. I discovered the bees clearly preferred the new blocks over cleaned sterilized old blocks. So here on the farm we build a few blocks every winter along with the other beekeeping woodware and put them out next to the older blocks and just rotate the blocks out. New ones up and old worn out ones into the firewood pile.

Ernie

That is interesting regarding liking the NEW blocks vs the old.

One thing I know about microwaving: I am not so sure it is doing the job you thought it was. I have seen bugs crawling around in microwaves while in operation. I don't think they have enough water or mass for the waves to have an effect on their bodies.

I have come to believe that the best method of managing these bees (without any personal experience!) is the slotted and stacked boards as mentioned by Lugar and sold by Crown Bees.