I have built several top bar hives, but only caught swarms for two. One of these has a front entrance, six inches long and 3/4 inch high. It is a 28 bar hive. The other is shorter, 20 bars long and has only three 7/8 inch holes bored in the side near one end for entrances and ventilation. The longer hive has a division board in it, placed at about the 20 bar point all summer.
The smaller hive has been building like crazy all summer--it is now crammed with comb and bees. The larger, that with the front entrance has always seemed sluggish. It is heavy, but the bees just did not seem to be working with the same enthusiasm as the smaller hive.
The fall honeyflow is on. If the bees do not make their winter stores now it is curtains. I decided to try something; I brought the division board hard up against the last comb. I plugged the entrance, cut it down to a 2/4 x 2 inch slot.
That was two days ago. This morning the re-worked hive is going great guns. More take-offs and landings than O'Hare. Bees standing in the doorway fanning.
I suspect that there is some relationship to the comb orientation and door position in this hive, and that the hive was drafty. From now on all my TBH's will have the small side entrances.
Are you sure it is the entrance size and not the change in the volume of the hive? in reading the Hardison article that Miki posted he relates the same problem when he tried to use too big a hive in NM. THey do better in a smaller space.
My experiments with entrances this year:
TBH #1 - side entrance about 1 x 5 inches. Good strong hive full of comb.
TBH #2 - end entrance, 1 x 6 . Strong hive full of comb.
TBH #3 - side entrance with 1 x 5 inches AND 3 3/4 inch holes drilled in bottom. They ignored the drilled holes and only use the side entrance. This hive is the weakest. Still lacks comb in the end, where the entrance is. So maybe the extra entrances do NOT pay off and you are correct.
I guess I better go block off those bottom holes in TBH#3!
Here is what I observed, In late June I installed new pkgs. I put a follower board in place of bar 15, when they reached 9 bars I pulled the follower out, why? I don't know, I think I should have left it in. They did not go past bar 9 untill this week when I put 5 liters of syrup in 3 days and its almost gone. If they make it to the next season I will keep the board two bars ahead of them. One variable I cannot discount is the late start. next season I will start one late June and see.
Procrastination is the assination of inspiration.
I tend to think that hive volume plays a big part when the bees are not super-strong, particularly if the ventilation is a bit much.
Ms. Naomi Saville, an aid worker in Africa told me earlier this year that the hives used there are small--I forget the volume, but much smaller than we use. Then there is the research discussed on this forum earlier this season that holds that the proper entrance is about l5 Sq. Cm. Three One inch holes just about perfectly fit that.
I think that we have a lot to learn yet about TBH's.
I have switched to the side entrance as well. Mine are about 12" x 3/8" which are open in the summer and reduced to about 4" in the winter.
After reading the research by Dr. Tom Seeley, et.al. about a swarm's nest preferences, I decided to follow bee biology. The smaller entrance makes quite a difference. It appears the bees can more easily control the hive environment.
There are fewer bees fanning, fewer water carriers, more bee flight and earlier flight than in either my standard or long hives with a conventional entrance. When my other hives are bearded out, my tbhs are operating as efficiently as ever.
That is one of the things I noticed; no bearding. On the hottest days the bees have one of the three entrance holes converted to an "exhale" port, bees standing in it fanning. The other two seem to continue as sally ports with bees coming and going. No comb collapse or other problems even though the hive is full of comb.
The top bar hives are very easy to fog with the FGMO, too. I lift the very back bar about a half inch and blow the fog in until it is coming out the entrances, then tap the bar back down. The bees will then pull the fog out thru the entrance.
I did have some bearding in one of my TBH's this year. It was the one with the entrance on the end and it had a shiny tin roof instead of flat white paint on plywood.
It was also set in a north south direction so the entrance was not shaded by the overhang.
Once I propped open the top the bearding diminished dramatically...