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Grass anthelids

Very high numbers of grass anthelid caterpillars (Pterolocera sp.) have been found in a pasture paddock west of Geelong, in the Central district of Victoria. The caterpillars were found across the entire paddock, which is a normally used as a horse grazing paddock. Although they are considered a relatively minor pest of pastures and cereals, there have been a number of reports of grass anthelids this year. Grass anthelids were also found from late winter through spring last year in the Mallee and Western districts of Victoria. In some instances there have been dense swarms of caterpillars moving across pasture paddocks in ‘bands’, removing most of the vegetation as they go.

Grass anthelid larvae feed on grasses and their numbers usually build up in pastures or roadside vegetation. In late winter and early spring, they can move into paddocks and cause damage to crops, with later instar larvae generally the most damaging. Species within the Pterolocera genus are not well understood, although in recent incidences the caterpillars found have always been brown or fawn in colour with black and yellow markings. Grass anthelids grow to 50 mm long and spin a dark brown cocoon in a vertical shaft in the soil, with the exit just below the soil surface.

Grass anthelid caterpillars are covered with distinct tufts of stout hairs, and can resemble other species including the processionary caterpillar (Ochrogaster lunifer). Recent research has indicated a link between processionary caterpillars and foal abortions in horses. It is believed the exoskeletons of this caterpillar can be picked up by grazing horses, and then penetrate the intestinal wall, leading to infection of the placenta and subsequent abortion. Although this caterpillar is superficially similar to the grass anthelid, at this stage there is no evidence to suggest that grass anthelids also cause this problem.

Click here for images of grass anthelid caterpillars.

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