Scales are a unique appearing insect. Most of us learned insect basics in grade school and are looking for three body parts (head, thorax and abdomen) and six legs. Then someone tells us a scale is an insect and we look at it and it appears to be one smooth surface and there are certainly no legs in sight. It is at this point where most of us basically just take the entomologist's word for it that these things are indeed insects. It is primarily the females that we see on plants, and female scales are wingless and usually legless as adults. Scale insects start as eggs. The nymphs hatch and do have legs, and this is the stage referred to as crawlers that moves around and infests different parts of the plant. After that first stage that is mobile, all the rest of the stages do not move.