Many times, our customers are refused service and sent home from a hairdresser with a cases of lice. However, at times, we provide a thorough, hour-long combing with our professional-quality comb and find absolutely nothing in the child's hair. This story is not unique. I have had many cases misdiagnosed by all kinds of people including medical professionals and educators.
You do need a trained eye, excellent lighting (natural sunlight is best), some kind of magnification (we use a magnifying visor similar to a tool a jeweler would use) and a tail comb or sticks to part the hair. Look on the hair near to the scalp as you will have the best chance of detecting an actual bug. They quickly crawl away so you need to be swift. The image here shows an adult bug.
Then look down the hair shaft to look for nits or eggs. These can appear brown, grey-brown or silvery in color. If you suspect an egg, attempt to flick it or blow it off. If it disappears, it's just a hair dandruff or debris in the hair. If it's firmly secured to the hair, slide it off between your finger nails and if you can, tape it to a white piece of paper. Take a picture of it with your smart phone and send it to email@example.com for a free nit diagnosis. Correct diagnosis saves time, money and tears. And if you do have a case, don't worry. Lice can be removed safely and effectively without the use of pesticides.