Lucerne flea

Agronomist, Phil Bowden (NSW DPI), has reported a number of crops displaying lucerne flea (Sminthurus viridis) damage around Cootamundra and Junee, in the South West Slopes of NSW. The occurrence is much more widespread than previously seen with economic damage to a range of crops including cereals, canola and pastures. The number of lucerne flea in some areas are in the thousands/m². Although quite patchy in distribution, Phil says that in these numbers lucern flea have the potential to completely destroy newly sown pastures.

Researcher, John Roberts (cesar), says lucerne flea numbers are also quite high in many areas of Victoria. John has observed large numbers in lucerne paddocks in the Western district and in parts of the Northern Country of Victoria. Additionally, reports have come in from the Wimmera district, Victoria. Consultant, James Ingrey (HO Ryder & Son), also reports that a number of crops and pastures are being attacked by lucerne flea in Grenfell and other districts in central NSW. James says lucerne flea are an ongoing problem, however, the damage this year has been far more extensive.  

Many annual crops are now at the stage where they will outgrow the damage fairly quickly, but young lucerne is particularly susceptible. Phil says the cold frosty mornings and dry conditions seem to favour this pest and growers would be well advised to keep a look out in paddocks. Lucerne fleas are up to 3mm long as adults and ‘spring’ off vegetation when disturbed. The pests work up the plants from ground level, eating tissue from the underside of the foliage.

They leave distinctive feeding damage of ‘windows’ of transparent leaf membrane. Crops are most likely to have problems where they follow a weed infested crop or a pasture in which lucerne flea has not been controlled. If spraying is required, do not use synthetic pyrethroids.