Nits are not the living insect, they are in fact the empty shells left behind after the baby louse (nymph) has hatched. What it leaves behind is an empty shell.
What do nits look like? Nits are much easier to see in darker hair as they are a white cream colour, they can be seen in fair hair but are far less obvious.
Why are nits so difficult to remove? When the female head louse, starts the process of laying an egg, it uses a liquid similar to keratin which is within the structure of human hair. (This is why you cannot breakdown eggs and nits as this would damage the hair). The liquid, is laid around the hair shaft, and then the egg is set to this cylinder on the top, the embryo is laid in the shell with liquid and a cap is placed on the top where it can expel gases and take in oxygen. The liquid hardens quickly and is cemented to hair firmly
Many people mistakenly believe that eggs just sit on the hair, but as you can see in photo they sit on the cylinder shape that surrounds the hair shaft. As it is fixed to the hair, the ONLY way to remove the nit, is to pull it down the hair shaft and off at the end of the hair.
How big are nits? Nits can be as small as 0.2mm wide, as the nit is an empty shell they can fall in on themselves.
How long will nits stay in the hair? They can stay in the hair for up to a year, but most will dry up and disintegrate in approx six months.
Will hair straightners or hair dryers get rid of nits? No they make the many nits smaller but they will not fall off. They can in fact make them harder to remove from the hair.
Any good news about nits? As the head louse has hatched and vacated the shell, nits are in harmless.