Head lice originate in eggs that female lice lay on the scalps of their hosts, according to Healthline. One female louse lays about four eggs per day and uses sticky material to attach them to the host's hair follicles, making removal difficult.
Head lice are extremely contagious, especially among children, but Heathline reports that they are passed only through head-to-head contact or by sharing hats and other personal items. Lice cannot fly or jump from one host to another.
Lice only live on humans and do not carry diseases, according to Wikipedia. Treatments include prescription drugs, over-the-counter medications and natural products, such as tea tree oil.