Re: Screened bottom boards:pest trap or ventilation?
jimbe, if you have shb larvae that are getting to the ground then that hive is probably already toast. Without a trap beneath it, sbb's do nothing in ridding the hive of shb. Regardless of sbb or not...shb will easily enter the hive.
The sbb by itself works well around here to reduce mite population some and for ventilation. Without powdered sugar treatments the impact on mite population is small. Mites falling below the screen will not re-infest the bees...they can't back up into the hive from the ground...or, from what I understand, even from an empty oil tray. In regards to ventilation they work very well, of course you need to have adequate ventilation in the cover, also.
It sounds like Millerbees is maybe selling some Beetle Jail products??? I use the Beetle Jail Jr.'s and like them...they seem to do a good job keeping the shb population down....which reminds me it is time to clean out and refill the traps. The BJ entrance trap seems like a neat idea. I've got a friend that has been using one on a hive this year...I'll try to remember and give him a call about it's efficacy.
Most reports that I've seen on the oil tray type of sbb seem to be favorable. If you can, get one that you can remove the tray from the *rear*....that makes life easier.
Warning: Rookie beek...take my postings with that grain of salt you keep in your pocket.