The Hive Mat has multiple purposes:1. The Hive Mat is a "building stopper" so that bees don't extend the comb from the frames to the lid. It can become very messy removing the lid when the comb extends from the frames to the lid, resulting in breaking of the comb. Nevertheless, when bees run out of space they start building comb under the lid, but with a hive mat present they cannot attach it to the frames. In such case, lifting the lid off is much easier.2. The Hive Mat assists the bees to regulate the brood nest temperature and humidity.3. The Hive Mat prevents that condensation, building up under the lid, is dripping down onto the brood and chilling it.
The hive mat is cut to a size leaving a gap of 10-15 mm all around between the mat and the hive box ends and side walls, and covering the entire core of the block of frames.When pushing all frames together and centering them in the hive box, a gap is created between the hive side walls and the block of frames, allowing air to flow between the side walls and the block of frames for ventilation. The hive mat should not hinder the air flow.With a correctly sized hive mat covering the top of the block of frames an inner box is created within the hive box. The outer combs forming the sides of the inner box, the side bars of all frames pushed together form the ends, the hive mat forms the lid of the inner box, only the bottom of the inner box is open for the bees. Warmth generated by the bees in this core block of frames/comb cannot escape through the top or sides.
We have seen hive mats placed as a sheet between the top box and the lid, creating a sealed cavity.There are two issues with that:1. Hive ventilation through the lid ventilation holes is prevented.2. Small ants and other little creatures can get in between the lid and the sealing hive mat through the ventilation holes and build their nest, undisturbed by the bees as they cannot access this created cavity.
A hive mat from woven material lets drip water through and therefore defeats the purpose.A mesh as a hive mat is unsuitable as water can drip through; bees will also close all holes with wax and propolis.Hive mats with felt or similar "hairy" material are also not suitable as bees can get tangled in the furry material and die.A sheet of plywood buckles due to the moisture, resulting in small cavities as good hiding places for wax moths larvae and Small Hive Beetles (SHB).We use vinyl (table cover) for the hive mat.
Whatever suitable hive mat you use, bees will glue it to the top of the frames with wax and/or propolis.If not scraped off, the layer of wax/propolis builds up, getting thicker and thicker when the hive mat is removed and placed back on again after hive inspection.Between the rows of wax/propolis between hive mat and top of the frames little pockets of shelter for wax moths larvae, ants, Small Hive Beetles will be created.To eliminate these hiding places it is important to scrape all wax/propolis off the top of the frames and from underneath the hive mat before putting the hive mat back on top of the frames.