Our 190 year old house is not only home to us, but at certain times of the year to migrating chimney swifts and to bats, as a box soffit under the second story eaves serves as nurse colony. In spring, female bats enter through many of the cracks and cranies in this aging wooden house, spending their days nursing their babies, and leaving at dusk to hunt for insects – part if what makes them important parts of our ecology. They leave a small scattering of guano near an open window that may be part of how they enter. At the end of summer, I wear a mask and using a vacuum with removable filter bag clean it up. From my reading, histoplasmosis is a danger with deep piles of guano – not the cup or so on my attic floor.