Adult lice will be the easiest to spot because they are the biggest. But at the size of a sesame seed, they still aren’t that big. Although lice vary in color, if you see a grayish-white or tan bug crawling through the hair, it is probably a louse. If you look closely at an adult louse, you should be able to see human blood inside it.
Look at the hair strands about a quarter inch (~0.5 cm) off the scalp. See if you can find lice eggs (often called nits) attached to individual hairs. Nits are extremely small. They look like tiny specks and will be glued pretty securely to the hair. If you see any, try pulling them off with your fingers. If you can’t easily pull them off, they are probably eggs and not dandruff.