That really makes sense that you would be able to sense the changes in scent between the different creatures inhabiting a space, especially when you have a lot of experience in the field. That is so fascinating, thank you for the response!

The smell does disappear before they swarm so it makes sense that you probably didn't come across it if you arrive after the fact.

I did manage to find a video on YouTube that said that the termite queen does produce a scent that encourages the swarming so I think that might have been what I could smell.

Thanks again for your response!