My screened bottom pallets have a gap 4" deep open front and back under the screen with the mite tray removed. Above the screen I have a slatted rack. Anyone have any opinions if screened bottom boards, or pallets in my case, might allow in too much light at the bottom of the hive. Some strains of bees build their comb in open air, how does light affect european bees ? And could this four inch space be allowing in too much draft, or should the slatted rack take care of it ?
My SBB have less than 4" (2 or 3, depending which one) but they sit on 4x4's across 2 cinder blocks. So when I do not have a "tray" (from May to September?, I left it in during cold weather) underneath most of the screen is about 8 inches at least off the ground. I did not notice a problem with the bees being exposed to drafts or light. They were all the way on the bottom of the supers during the summer.
Do you leave your trays off during winter?
I haven't gone through a whole winter yet with screened pallets. I installed on them the first week of January, and had the mite board on for the next few weeks. As my bees are in a temperate climate, I will leave them off except when monitering.
I also left my SBB's open all of the winter and didn't have any problems. I had so many bees this spring that I have had to do a split. I really like using the SBB's. I only put the tray in if I want to check for mites and then only leave it in 24 hours. I have yet to find any mites this year.
One problem I encountered with screened bottom boards and open mite trays occured when foraging bees were attracted to the debris on the mite trays or the odor of the hive escaping from the screen.
Those live mites are quite good at hitching a ride back into the hives.
This 'problem' provided quite an opportunity to observe the interactions between mites and bees, but I did close off any access to the trays by the bees.
I always leave my sbb's open, don't even use the trays to count mites, because I haven't seen any mites, so far. I did block the wind from the undersides of the hives during the coldest days of winter, but didn't use trays directly under the hives. I only have three hives, but they all made it through winter very well. Of course, our winters are mild compared to many areas of the country, so that doesn't really mean much. I haven't noticed any adverse effects of leaving them open all the time.