Screened bottom boards
Traditionally, most wood beehives have had [solid] wood bottoms. If the hive has a bottom entrance, there is an opening for the bees to enter/exit the hive, but the bottom of the hive is otherwise closed off to the environment.
A more recent design substitutes wire screen for the wood bottom boards, with the bottom of the screen open to the environment. Normally 1/8" screen is used, so bees cannot pass through this screen. Both light and air can freely pass. In some cases, there is a "count board / sticky board" that can be slid in place to mostly block off light and airflow through the open screen.
A variation of the 'open' screened bottom is to close off the underside of the screen with an "oil tray"; the oil is intended to kill anything getting in the oil (pests like varroa and small hive beetles falling/crawling through the screen are the target, but oil will also kill bees if they get in there). Passage of light and air are blocked with this variation.
Regardless of the merits of a screened bottom boards vs solid bottoms once the bees are established and brood is present, there is a serious issue with installing new 'packages' of bees into a hive with an OPEN screened bottom. ABSCONDING is a situation where bees don't like the hive, and decide to seek their fortune elsewhere. You don't want that to happen. Close off screened bottoms before installing packages.
Post #120 has a link to a study comparing productivity of open screened bottom boards to closed bottom boards: https://www.beesource.com/forums/show...-bottom-boards
Once a new hive has some brood to anchor it, absconding is less likely. At that point, some remove the closure board. As 'open' screened bottoms also allow light and air to freely pass through, outside air moving into/through a hive more freely than a solid bottom hive may have an impact on temperature and humidity inside the hive.
Putting an oil tray beneath the screened bottom blocks off passage of light and air through the screen. (Sometimes a tray may have a substance other than oil, like diatomaceous earth) ...
Last edited by Rader Sidetrack; 06-03-2017 at 08:50 AM.
USDA Zone 7A Elevation 1400 ft