Entomology (Study of Bugs)/Vanishing bumblebee nest
I live in an urban area of northeastern Ohio. This past June I began to notice bumblebees dropping down to near ground level next to my front porch. They were common eastern bumblebees, Bumbus impatiens. It seemed as if they had a nest in the vicinity. By standing watch near sundown, when the workers return for the night, I was able on July 2 to identify the hole they were entering. It was located in the brickwork of my front porch, about nine inches above ground level. Bushes surrounded the nest and creeping myrtle covered the ground. To me it seemed an excellent choice of nest site. It gave ready access to the abundance of flowering plants in my yard (and my neighbor's yard) while staying out of reach of the voles that are around.
With all seeming propitious, this month I began to realize I had not seen any worker bees dropping down for quite some time. And the population boom of bumblebees that typically occurs on my Rose of Sharon in mid to late July never materialized. I became concerned about the nest and began to watch it again around sundown for returning workers. Over several days none ever showed, and in retrospect I feel the nest was probably long gone by the end of July.
The intact brickwork around the entrance rules out the possibility that voles or other large animals dug out the nest.
I realize you may not be able to give a definitive answer as to the cause of the nest's demise, but I wonder if you could enumerate the possibilities.
My only suggestion is the possibility of the death of the Queen or the departure of the Queen. If you noticed a decline in activity since the middle of June the absence of a Queen seems likely.The workers have been slowly dying off and new ones are not emerging.
I was at the Farm Park yesterday and there were plenty of bumblebees visiting flowers. If you are from Northeast Ohio I am sure you are acquainted with the farm park
I live in Wickliffe and am a biology teacher at Lakeland.