About Psyllids: Psyllids, also known as jumping plant lice or lerp insects, are sap-sucking insects related to whiteflies, aphids and scale insects. In Australia, there are hundreds of species of psyllid, most of which are of not of any economic significance. Most psyllid species are host specific and live and feed only on a group of closely related plants or a single tree species), including the psyllids which feed on eucalypts.