Context. Significant resources are spent annually in New Zealand controlling pests to mitigate impacts on native biodiversity and agricultural production, but there are few reliable estimates of the benefits. Concerns have been expressed about inconsistent monitoring methodologies, differing frequencies and intensities of control across organisations, and poor definition of desired outcomes.

Aims. To conduct and report on a survey of animal and plant pest control and monitoring by regional agencies, to identify issues with current practice and to provide advice on improvements.

Methods. We surveyed 15 regional agencies in New Zealand about the pest control and associated monitoring undertaken during 2005–08. We recorded the pests targeted, the control work done and its operational details, any result and/or outcome monitoring conducted, and estimated costs.

Key results. About 21% of the NZ$20 million expenditure on pest control was for monitoring. Excluding compliance (62%), monitoring changes in pest populations accounted for 31% of the total monitoring expenditure, whereas only 7% was spent measuring response in the resource that was supposedly being protected. The most common monitoring design (71%) comprised a single treatment area with no non-treatment area, in which only results were monitored. Only three programs (4%) had both treatment and non-treatment areas and both results and outcome monitoring.

Conclusions. Such limited outcome monitoring constrains severely the ability of regional and local authorities to provide robust justification for their pest management activities and expenditures.

Implications. Improved outcome monitoring requires better design of and additional resources for monitoring programs, improved institutional/political support for long-term programs, and better definition of long-term outcomes and objectives for pest management.