Key points
- Argentine stem weevil (ASW) is a common and serious pest of grasses, maize and cereal crops throughout New Zealand.
- Adult feeding is generally insignificant and most damage is caused by larval feeding inside plant tillers.
- Argentine stem weevil is difficult to control with insecticides, but endophytes are effective in some grass species.
- A biocontrol agent is present throughout New Zealand, but it appears to be less effective now than it was in the first 5-10 years after its release in the early 1990s.