Mary stopped halfway down the stairs. Something was crawling around the floor at the bottom. A lot of somethings. They were grayish and round, and at first she thought they were rats. Their insect-like legs and lack of tails discounted this immediately. She carefully stepped closer to the end of the staircase, and realized these creatures weren't supposed to be visible to the human eye.
She peered around the corner and confirmed that they were coming from the living room. An army of them was gathered around and underneath the couch. Dust mites? Probably. And with all that spilled growth serum they've had a field day. She could see the floor and lower parts of the walls were already covered in a strange white fuzzy substance they were depositing. It was almost as bad as the mess the mosquito had made in the upstairs hallway.
Still, in her diminutive state she was going to have some trouble. Although they were the size of rats, to her they were more like small dogs. Could they bite? Did they often attack things bigger than them? There was only one way to find out and get the vials back.