Not ex nihilo

A blue bottle fly, so indolent that I vacuumed it off a mirror with a dustbuster, arrived with the roast chicken. When chicken bones go in the trash, a fly or two appears out of nowhere, even in my home reasonably screened against intruders large and small. The toad on my lanai didn't appear to eat flies. Or anything else that I could see. How it got here, two stories up, and not a pond in sight, was another unknown. It sat nestled in the moss of an orchid where it slept most of the time, when it wasn't napping.