Dangerous bloodsuckers on the rise in Germany: Scientists warn about black flies. Black flies are only two to six millimeters long and look like a small housefly.
They are characterized by particularly aggressive stinging behavior towards mammals and humans. Female animals use sharp “teeth” to scrape the skin of their victims in order to suck blood. With the blackfly saliva, anticoagulant and anesthetic substances get into the wound. This can cause allergic reactions, swelling and bruising in some people.