Strange sound

[Donald]

I was loitering by the hives counting butterflies for the survey that is on this week, and heard a low rasping sound coming from one of my hives. Not queen piping which I have heard before and is quite high pitched. Much lower, like a cricket or a sound you could make with your tongue. I had a quick look and there were no signs of queen cells, plenty of young brood and eggs, lots of bees. I did see a drone being evicted from the entrance, and there was a small crowd of bees on the front porch.

I wondered if it might be a death's head hawk moth, but the description in my moth book is "an audible squeaking sound" which doesn't sound right. Any ideas - are they trying to tell me something?

Donald