Deer ticks, also known as black-legged ticks, are small arachnids that primarily feed on the blood of mammals, birds, and reptiles. They are commonly found in wooded or grassy areas and are most active during warm months. Adult ticks are about the size of a sesame seed, while nymphs are even smaller, making them difficult to spot. These ticks are known for transmitting diseases, including Lyme disease, which can cause serious health issues in humans and pets. To reduce the risk of tick bites, it is advisable to wear protective clothing, use insect repellent, and check for ticks after spending time outdoors.