New research has found that enzymes in the mite's dropping cause an intense irritation on the animal's skin resulting in inflammation, scabs, discolouration of thickened skin, wounds open to bacteria and/or loss of wool. Once it was thought that the mite pierced the skin of its host with its mouth in order to feed, but that thinking has now changed. Most outbreaks of herd infestation happen in the autumn, or if animals are kept indoors in winter. If dislodged from its colony a sheep scab mite can remain active for about 15 days before becoming dormant prior to death. Herd infestation happens through direct contact of animals or by transferring from infested wool or hair left on fence posts or in farm chutes or trucks. Unless disturbed the mite will spend its entire life feeding on one animal. In perfect conditions egg to adult takes approximately 11 to 19 days, with adults living for up to 40 days. The adult sheep scab mite lives in colonies in high humid conditions feeding on the skin of sheep, or cattle. By comparing the two ancient relatives today the shared features become apparent in their life styles and by the production of aggressive digestive enzymes designed to make food for the mites. Even though this evolutionary separation happened millions of years ago, the house dust mite has retained some of its parasitic features. At some stage the house dust mite changed to become a scavenger eating organic or decaying debris that littered nest sites. In ancient tines the parasitic house dust mite and the sheep scab mite were not burrowing skin mites like scabies, but lived on the surface feeding off their warm-blooded hosts. The house dust mite is not as harmless as portrayed. By comparing the lives of the two mites living today echoes of past parasitic behaviour become apparent. At some stage in time the house dust mite became a scavenger less dependent upon the health of its host for survival. Millions of years ago the house dust mite and the sheep scab mite lived together as parasites of warm-blooded animals. Mite Research / For the Curious / House dust mites were once mange mites