Scabies is caused by a small mite, about a 1/60 th of an inch long which burrows just under the surface of the skin, they burrow under the layer that rubs off if your children get sun burnt or are rubbed hard with a towel. It is very difficult to see where the burrows are but most of them tend to be on the hands and wrists and between the fingers.
The mite is a tiny bump at the forward end of the burrow. Whilst it is possible to see them with the naked eye it is very difficult. The female mite does not leave the burrow voluntarily and it (the tunnel) becomes full of fecal pellets, hatched egg shells and live eggs as she continues to burrow forwards. The infection is very itchy especially at night as your children get warm in bed.
Toddlers can have the mites for between 6-10 weeks before they start to show any signs of the infection though and during this time they can pass it on to other people.