 The infective larvae (L3 larval stage) migrate to the mouthparts of the fly, where they are passed on to the horse when they feed around the horse's moist areas such as wounds, nostrils, lips, and eyes.If the larvae are deposited into open wounds, or broken skin they can cause intense granulomatous reactions, producing an ulcerated irritation called Habronemiasis, or more commonly, "summer sores".They may also invade the eye and the eye membrane causing a persistent conjunctivitis.