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Lucerne flea

Jon Shuter (NSW TAFE) has observed lucerne flea (Sminthurus viridis) attacking a pasture paddock near Wagga Wagga, in the South West Slopes of New South Wales. Jon says the distribution of lucerne fleas is patchy, with higher numbers and significant damage occurring in one corner of the affected paddock.

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. Keep a good look out in paddocks, particularly in canola, lupins, lucerne and clover.

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. Consider implementing control in the season prior to sowing to minimise numbers. In crops, spot spraying is generally all that is required; do not blanket spray unless the infestation warrants it. If spraying is required, do not use synthetic pyrethroids. Jon says omethoate was successful in controlling the lucerne flea outbreak.

Snout mites (which have orange bodies and legs) are effective predators of lucerne fleas, particularly in pastures, where they can prevent outbreaks. The complex of beneficial species (including snout mites) should be assessed before deciding on control options.

Click here for images of the lucerne flea.

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