Lyme disease tick (Ixodes ricinus). Scanning electron micrograph of an adult female Lyme disease tick, the principal vector of the disease in Europe. Male ticks attach, but do not feed or become engorged and so do not transmit Lyme disease. It is a blood-sucking parasite of animals and humans. Here its specialised mouthparts used to pierce the hosts skin are seen. The hypostome (centre) is inserted with its backward pointing barbs anchoring the animal. Blood flows along the hypostome. Sensory pedipalps are on both sides of the mouth. Lyme disease occurs when the biting tick transmits a bacterium to humans. Lyme disease causes fever, muscle pain, and inflamed joints. Magnification: x100 when printed at 10cm wide.