Why bees death in the syrup? Sometimes it can more than hundred death floating bees. I used sponge or leaf to let bees stay float on syrup. How should I prevent?
Floats and ladders. And some will die anyway. Most get stuck and can't climb out.
Any kind of feeder with much exposed syrup should have floats in it. Any kind of feeder where the bees have to climb down to the syrup should have ladders made of #8 hardware cloth or window screen wire. If you can limit the access to the surface of the syrup with #8 hardware cloth you can also reduce the drownings. Brushy Mt makes a frame feeder that has a #8 hardware cloth ladder shaped like a oval that runs all the way tot he bottom and the rest of the opening at the top is blocked, so the bees only have access to about a three inch length of the surface of the syrup.
If you insist on open feeding make raft using a wood frame and window or 1/8 -- #8 screen. I prefer feeding each hive internally to reduce robbing between hives. A jar or can upside down inside a super works very well. Punch holes in the lid with a 4d nail so the it just barely splits the tip of the pyramid of the nail point.
this sounds like a heavy metal band.
Only if you beat on the cans. Like with glasses, the syrup level in the feeder cans changes the tone. Put enough together and you get a tin Xylophone.