Peter wrote:
> Incidentally, icing sugar is unsuitable for feeding bees as the trisodium
> phosphate will not dissolve in water and leaves a thick sludge in the
> feeders.

I was always told the same thing as Peter is saying. Years ago I had a
contract   to buy all the salvage sugar at the largest freight salvage in
the U.S.. They said they had 50 bags of sugar for me on two skids. When I
picked up the sugar I found the sugar was Domino brand icing sugar in
perfect bags.
I called Domino in New York and talked to a chemist. I called Beltsville. I
called other beekeepers. I fed the sugar in late spring. I had no trouble
mixing with water. There was no sludge.  and the bees took the syrup a
gallon at a time in one day.

I was told by Beltsville not to winter on icing sugar and feed only when the
bees are flying. I also found two other beekeepers which had fed icing sugar
on a large scale without problems. I tried to resale the sugar first (at a
profit) but to no avail. I did sell a 50 pound bag to a neighbor lady. I
wonder if she has used up 50 pounds of icing by now?

Bob