Although they're very small, lice can be seen by the naked eye.
Here are things to look for:
Lice eggs (Nits) These look like tiny yellow, tan or brown dots before they hatch. Lice lay nits on the hair shafts close to the scalp, where the temperature is perfect for keeping warm until the hatch. Nits look sort of like dandruff, only they can't be removed by a brush or shaking them off.
Scratching. With lice bites come itching and scratching in 50% of people only.
Small red bumps or sores from scratching .