I am not sure there is a good way to tell what the hive is bringing in beyond the pollen on back legs. I see my bees at my water source, so I know some (a few %) are bringing in water and a lot are bringing in pollen. I sort of assume that if they are bringing in pollen they are probably also bringing in nectar unless, this is probally also true for you unless you are in an area with nectar poor plants.@elmer_fud Exactly what I did a week ago. Brought home a nuc and per advice of the seller transferred it to a ten frame the same day. New, never used rapid feeder and noticed the bees had not found it four or five hours later. Seemed the most logical thing to do was dip my finger in and dribble a few drops down the side of the center tube. By the next day they were busy as bees working the 1 to 1. Hope they turn every drop to wax! Just starting out so need that drawn comb.
Assuming they are also bringing in nectar since there almost always seem to be more bees with out pollen than with. Is there any way to tell what the other foragers are doing? Nectar, water, scouting... My guess is the clumsy ones that do not know how the entrance works are young bees on their orientation flight. Pollen gathers and a good portion of the unknowns fly straight to the center of the Guardian entrance.
Good theory on the temperature of the syrup! Daytime highs have been approaching 70, but overnight lows have been in the mid to upper 40's. Temps are on the rise though.Other thing that may help is running a few drops of syrup down the ladder/bee tube from the feeder into the hive. I suspect doing this may guide some bees in with the logic of they are following the sugar trail.
What have the temperatures in your area been? Is it possible that the top feeder is to cold, and the entrance feeder was getting warmed by the sun?