Black-legged ticks, also known as deer ticks, are small arachnids commonly found in wooded and grassy areas. They are known for their role in transmitting diseases, including Lyme disease, which can affect both humans and animals. Adult black-legged ticks are typically active in the fall and spring, while nymphs are most active in the late spring and summer. These ticks have a distinctive dark brown to black coloration and can be as small as a poppy seed. They attach to their hosts to feed on blood, which can take several days. Proper precautions, such as wearing protective clothing and using insect repellent, can help reduce the risk of tick bites.