Tropical grass webworm (Herpetogramma licarsisalis) implications for dairy farming in Northland

Abstract

The presence of larvae of Herpetogramma licarsisalis (tropical grass webworm (TGW)) in pasture on the Aupouri Peninsula in Northland New Zealand was confirmed in March 1999 A delineation survey undertaken in late March 1999 found an infested area of approximately 37 000 ha of which 4450 ha was in dairying The establishment of TGW in the area has been confirmed by ongoing monitoring of populations from 1999 to the present Populations decline to extremely low numbers over the winter months with the main pasture damage period in early autumn (March/April) Infestations to date have been mainly confined to kikuyu pastures In 1999 and 2002 visual estimations were made of pasture damage by TGW The implications of this damage are discussed within the context of management practices and economic constraints for dairy farming in the area