lerps on gum leafclose up of lerps

Lerps are protective covers constructed by the nymphs of jumping plant lice (Order Homoptera/Hemiptera, Family Psyllidae). Lerps are formed from the honeydew excreted by the nymphs on the leaf surface. The honeydew consists of sugars and amino acids which crystallises on contact with air. Sooty moulds may grow on the honeydew, giving both the lerps and the leaves a blackened, sooty appearance. The shaped and size of lerps varies according to species and some can even resemble sea shells, as is shown in the photographs above.

Both the adult and nymph psyllids are sap suckers, using their mouthparts (usually in the form of a stylet) to extract plant juices from the leaves. Heavy infestations of nymph psyllids results in major defoliation of trees due to leaf drop and as result psyllids are considered pests. In fact, an Australian psyllid, Glycaspis brimblecombei, commonly known as the red gum lerp psyllid, has, since 1998, been a major pest of the Australian red gum trees now naturalised in California. In the summer of 2000, Californian entomologists introduced a parasitoid wasp (Psyllaephagus bliteus), the natural predator of G. brimblecombei, in order to control it.

Photos courtesy of Peter Chew http://www.geocities.com/pchew_brisbane/index.html