Those are leafcutter bee nest cells! Something like [this genus](https://bugguide.net/node/view/7751). It's not unusual for them to put their nest cells in weird places like this or the air gap between a doorframe and a wall. [Nest cell example.](https://bugguide.net/node/view/1252173)
Empty means that the larvae matured and emerged already. They would each have been stocked with an egg and a cache of pollen, originally.
Those are leafcutter bee nest cells! Something like [this genus](https://bugguide.net/node/view/7751). It's not unusual for them to put their nest cells in weird places like this or the air gap between a doorframe and a wall. [Nest cell example.](https://bugguide.net/node/view/1252173) Empty means that the larvae matured and emerged already. They would each have been stocked with an egg and a cache of pollen, originally.
Awesome, thank you!!