Lerps and psyllids
Lerps are protective covers made by nymphs (larval stage that resembles adults) of jumping plant lice or psyllids (Family: Psyllidae).
Nymphs excrete honeydew on the leaf surface and the sugars and amino acids in the honeydew crystallise in the air to form lerps. Leaves can look black and sooty when moulds grow on the honeydew. Lerp size and shape varies between species of psyllid.
Adult and nymph psyllids are both sap suckers. Heavy infestations of nymphs can cause significant leaf-drop, defoliating trees.
- Sugar lerps (Glycaspis species)
- squarish to conical
- up to 5mm diameter
- usually white but sometimes yellowish
- sooty mould growth.
- Basket lerp (Cardiaspina species)
- loliage can appear purple or brown.
- 1-4mm long
- lacy and basket-like, mostly on lower leaf surfaces (C. fiscella) or ribbed, scalloped, yellow mostly on upper leaf surfaces (C. maniformis).
- Creiis psyllid
- constructs round, semi-transparent lerps that shelter the feeding nymphs.
- Spotted gum psyllid (Eucalyptolyma maideni)
- lerps are white, flat and fern-shaped.
- Sugar and Basket lerps Cardiaspina and Glycaspis psyllids occur in northern and South Eastern Queensland.
- Creiss psyllids occur throughout coastal New South Wales to the Queensland border.
- Rose gum and hybrids (Eucalyptus grandis)
- Gympie messmate (E. cloeziana)
- Blackbutt (E. pilularis)
- Spotted gum (Corymbia citriodora).
- Glycaspis species do not cause direct damage to leaves, but produce honeydew, which promotes the growth of sooty mould.
- Cardiaspina species can cause severe defoliation due to diseased cells forming around feeding sites. At high densities, the whole leaf becomes diseased and sheds.
- Creiis feeding produces reddish-purple leaf tissue that becomes diseased and brown, and often dies. High densities of lerps discolour the crown. An important pest of eucalypt plantations.
- Eucalyptolyma maideni is common on spotted gum but doesn't cause defoliation. High densities may encourage sooty mould growth over leaves.
Resources and research
- Carnegie, A, Lawson, SA, Smith, T, Pegg, GS, Stone, C, and McDonald, J 2008, Healthy hardwoods: a field guide to pests, diseases and nutritional disorders in subtropical hardwoods, Forest and Wood Products Australia, Victoria.
- Pests and diseases image library (PaDIL)
- Australian Pesticides and Veterinary Medicines Authority (APVMA)
- Last reviewed: 12 Dec 2018
- Last updated: 12 Dec 2018