Cockchafer damage to broadacre crops

Page last updated: Tuesday, 23 July 2019 - 1:17pm

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Cockchafers belonging to the genus Heteronyx are typically not regarded as a pest of agriculture. However, two have been seen as occasional pests, with H. obesus causing severe damage to a range of crops and pastures, and H. elongatus causing damage to pastures and eucalypt seedlings.


In 1989 a native cockchafer belonging to the Heteronyx genus caused damage to crops around Harrismith in Western Australia. Damage was sustained on only a small number of farms, however it was severe with larvae causing losses of over half a million dollars by root damage to wheat, barley, oats, lupins and pastures.

In some cases paddocks did not yield at all and suffered from wind erosion during the following summer. Infestations of 20 grubs per square metre caused crop thinning while more than 50 grubs completely destroyed crops. Damaging infestations of H. obesus occurred around Harrismith again in 1991 and 1993 indicating a highly synchronised two-year life cycle. 

Crop damaged by cockchafer larvae
Crop damaged by cockchafer larvae

H. obesus adults have been caught from Geraldton to Esperance  indicating potential for outbreaks in other cropping areas.

Considering that many Heteronyx species are leaf feeders, feeding on eucalypts, melaleucas and other native plants, current revegetation and commercial tree plantation programs as well as crops, could be under threat.

Cockchafer adults on native tree
Cockchafer adults on native tree


Rob Emery
David Cousins