Proper Hive ventilation is something that has long been completely overlooked or misunderstood by beekeepers forever.
The basic's are thus: By what ever means the hive should have a vent at the bottom and a vent at the top. They do not need to be the same size. The important part is that there is a way for the moisture that would normally accumulate on the inside of the hive top to be exhausted to the outside while still suspended in the air. Once moisture condenses upon the underside of the top a method of having it exit the hive in a way that doesn't endanger the bees is necessary. For this screened bottom boards or bottomless hives are best. In the summer the bees get a lot of the moisture necessary for cooling the hive from the evaporation taking place while processing the nectar into honey but the bees will still seek outside sources of coolant (water). A certain amount of water is also necessary for mixing with the honey and pollen, as well as creating royal jelly, for feeding the larvae.
Bees in a hive with a high inner temperature will beard to the outside of the hive. This bearding is the result of nurse bees being forced from duties within the hive in order to create enough space to cool the hive (ever been in a crowded room where everybody is sweating inspite of the airconditioning?). A hive that is vented both top and bottom does several things, Air flow for those bees engaged in HAVC (airconditioning) duties need only direct the air flow in one direction as the vent at the top of the hive provides and exit for that upflow. In hives without any top or bottom vents the bees mush pull air in one side of the entrance, force it up to the top of the hive on one side of the hive and then the bees at the top must force it back down the the other side. this requires a lot of bees to preform and that is why, on a hot day, you'll find bees washboarding at the entrance and if you take the top off you find bees in the same tail up, wings working, formation atop the frames as the bees at the entrance. Again vents at both the top and bottom allow the bees to work in one direction and allows many more bees to graduate to foraging. Vents, along with a slatted rack provides both a place that allows more bees to remain in the hive and being productive instead of bearding idly on the front of the hive. A slatted rack gives a place for the idle bees that must move off the frames to reduce heat generation to festoon but as a platform for the HAVC bees to work the air flow from inside bottom of the hive instead of outside entrance and inside inner top.
So, proper ventilation provides better air flow and commitment of less bees to HAVC they can then be promoted to foragers, giving a greater work force towards food reserves. It allows the bees to work less hard to accomplish the same chores and use less bees in doing it. It also allows more nurse bees to stay on the combs allowing a greater sized brood nest which makes for a stronger hive.
All these things mean the hive also has more guard bees to protect the resources of the hive from robbers and pests.
Top entrances are nice, I like them, but not required. But due to thirty years of experimenting with ventilation issues in bee hives I now use bottomless hives with slatted racks and a reduced upper entrance. A few bees will use the top entrance, the vast majority will use the bottom entrance by natural inclination. My hives have adequate ventilation and ways to accomplish all the housekeeping chores. Even keeping the bottom board clear of debre is easier as they only need to clean the upper sides of each slat as most of the debre drops to the ground between the slats. I've also found, using this system, that the ants are prone to not enter the hive as those things they are after, wax, ejected brood (hygenic behavior), assasinated intruders, etc, are dumped on the ground where they have ready access and little reason to invade the hive (For the ants this is practically having breakfast in bed).
That's the short course on Bee Hive Ventilation, I hope it helps.
Topic: top vs bottom entrance in hot weather (Read 7802 times)