These are very small, often dark insects, forming a quite distinct order. Each of the legs ends in a protrusible vesicle, and the two pairs of very narrow wings have hairy edges. In Denmark they are sometimes known as cholera flies. This is because they occurred in enormous numbers in Copenhagen during the cholera year 1853, and it was erroneously thought that they had some connexion with the disease.
Most thrips are associated with plants, where they feed on the sap.
They fly very well, but normally only take to the wing on warm, still days. They may then occur in enormous numbers and can be very irritating when they crawl around on the skin producing a tickling sensation, and because they have a tendency to creep beneath clothing and into ears, mouth and eyes. Although, as already mentioned, they are plant suckers their mouthparts can penetrate human skin.
Under certain circumstances thrips enter houses in large numbers. They have a special habit of creeping into narrow spaces and they are therefore found behind wallpaper and even behind the glass of pictures. However, they soon die in the dry climate of modern houses. The species usually seen is Limnothrips cerealium.