Ticks are parasitic arthropods that feed on the blood of humans and animals by attaching themselves to the skin with their mandibles. They carry and transmit several diseases in this way, most notably Lyme Disease, which can kill humans. However, if a tick is removed from the body before it has had the chance to transmit any bacteria, there is little or no risk of contracting a disease. Some sources cite the limit as 24 hours, some two days, but a good rule is that the longer the tick has been on you, the higher your chances of contracting the disease.
Learn the normal size of a tick. Nymphs (young ticks) are roughly the size of a poppy seed, while larvae are smaller. Adult ticks look like very small spiders, with females usually larger than the males.
Think back to the last time you could have possibly picked up a tick. Even if you just sat in your backyard, you may have attracted a tick. Count the hours in between the activity and the discovery of the tick.
Examine the tick on your body. Determine if it is engorged by comparing it to the regular size of a tick. A tick that has not yet become engorged with blood has probably not been on the skin long enough to transmit a disease, according to the American Lyme Disease Foundation. This means it has probably been on your body for less than 24 hours.