The realization that progress begets diagnostic problems confronted me this spring and summer when, during visits with family friends, I had occasion to treat their 7-year-old daughter for a textbook case of multiple bites. The clinical picture was clear. She complained of itching at night and of being unable to sleep; a morning examination revealed multiple urticarial papules with punctate centers, characterized by evanescent lesions. A cursory search of the child's room at first was negative, but after a careful examination the mother noticed on the bed of which appeared to move. Under the microscope these dust particles proved to be bird lice, which had been sucked in through the duct of the room air conditioner from a bird's nest outside the window. Removal of the nest cleared the child's condition. Medical Arts Bldg. (1).