I believe that screened mesh bases create an easy and accurate assessment tool for all beekeepers. All my hives, which are all Top Bar Hives, have screened bottoms, with a hinged wooden bottom board which enables the hive to be closed up in the colder season. I would not be without my screened bases as I think they are a great Integrated Pest Management tool and also a simple way to give you valuable insights into the condition of your hive without having to open and disturb the bees. A screened bottom also gives me direct access to the colony so I can conduct some of my organic varroa treatments, again without having to open the hive. I build my hives with stainless steel varroa mesh which give me great longevity. I use old real estate signs (corflute) as my sticky boards to help monitor the hive debris. I spray these boards with cooking oil and they sit between the stainless steel screen and the closed wooden bottom board.
I would like to share with you some of the images I have collected over the years of my 'hive trash' that has collected through the bottom screens. I hope it demonstrates what a valuable insight you can gain form this type of hive modification.
In a solid bottom hive, if a varroa falls off a bee it can quickly climb back up the sides of the hive and attach itself to another hive bee. Studies have shown that if a mite falls off a bee through the screened bottom and out of the hive it is unable to transport itself back into the hive. Ants, cockroaches, spiders etc may even hopefully make a meal of these mites.
Fresh pollen pellets can sometimes be seen in a line across the board. This can indicate the location of the front edge of the brood nest. Pollen on the sticky board does not necessary indicate that the colony is queen right as sometimes queenless colonies will collect pollen. Foraging bees will sometimes drop pellets of pollen when they are being transferred within the hive. The comb adjacent to the first brood comb at the front of the hive typically contains a considerable amount of pollen. If pollen collects in a straight line across the sticky board this will indicate where the brood nest begins (Mangum, W. A, 2012, pg222).
Bees produce wax glands on the lower side of their abdomens. as the bees remove and manipulate these tiny flakes some fall to the bottom of the hive, through the screen and onto the sticky board. A colony only builds new comb during a nectar flow or when the colony is running out of storage space, or if this colony is a recently hived swarm.
Chalk brood is a fungal disease affecting the brood. It is a relatively common disease and most strong hives will overcome it naturally. The causative fungus is called Ascosphaera apis. It causes the death and mummification of sealed brood. Normally by increasing the ventilation through the hive symptoms will disappear. It is most common is spring.
Pieces of wax, yellowish in colour, covering the sticky board along with bee parts can indicate robbing. The robbing bees or wasps frantically chew the comb as they remove the honey. The ensuring fight to protect their food stores results in insects being torn apart.
If, in addition to these chewed bits of wax cappings, you see bits of grass, leaves or small black pellets this could indicate that a mouse is nesting in the hive.
Screened bottom boards allow me to easily and effectively treat my hives organically using formic acid or oxalic acid by vaporising. Watch below how I do this with my Top Bar Hives. I would love to hear your experiences or thoughts on your hive setups.