Community Pest Control

The task of pest management is much greater than can be dealt with by Horizons alone, who can only do so much to manage the effects of pests in our region with the resources at hand. The future of biosecurity in our patch of New Zealand needs this to be a joint effort with our community and other agencies that have a role in managing the effects of pest animals on our environment and economy.

Field horsetail

Field horsetail (Equisetum arvense), has become a serious invasive pest of pasture, crop and riparian areas in our region. Traditional weed control measures are costly, minimally effective and are struggling to control or even reduce the spread of this weed.

In early 2018 a bioagent, the horsetail weevil, Grypus equiseti, were released in the Rangitīkei District near Bulls to help control the invasive weed. The release was managed by the Rangitīkei Horsetail Group with Horizons, NZ Landcare Trust and Landcare Research.

This page is a hub for the most relevant and helpful information available. Partner organisations in the study of field horsetail include NZ Landcare Trust, Landcare Research, and AgResearch.

Current progress

2021 saw the successful deployment of the field horsetail weevil, grypus equiseti. The success of this weevil has been measured through the six deployment sites the weevils were placed at, two of these sites have shown areas where the weevil has eaten into the stem and subsequently laid its eggs. These eggs become larvae and migrate down the stem feeding on it at the same time, consuming and breaking up the roots. 

This success comes after an 8 year project led by the Rangitīkei Horsetail Group who endorsed scientists to carry out research which led to the selection of the weevil. The weevil became an ideal canditate as it only ate field horsetail and did not migrate to any native plants. 

While the first stage of the project is now completed there is still more work to do to ensure successful continued survival and natural breeding continues to occur. The weevils move only a few kilometres per year so this long-term project will focus on the control of field horsetail rather than eradication. Hopefully in the future we will have a nursery of weevils to increase mass depyloment. 

Alistair Robertson completing the final release on his farm

Scientists discussing the work that went into getting the weevil into New Zealand, the lab environment for breeding, and the impact the weevil could have

August 2015-Update


Weeding out Field Horsetail


Field Horsetail - Control Options


Preventing Freshwater Weed Invasions

Our region has been forged by rivers, and along with our lakes they are sources of food and enjoyment for many of us. By checking for pest weeds and pest animals, and cleaning your gear or drying it thoroughly, you will be protecting our waterways. Unfortunately we have several freshwater pests already causing problems in our region. By following the simple steps of 'Check, Clean, Dry' we can stop the spread of these pests such as didymo establishing in the North Island.

The Check, Clean, Dry crew are available to come and talk to groups, set up displays at your event or to support cleaning stations for sporting events in and

around freshwater spots in our region. If you would like to arrange a visit from the crew or some professional development for your staff to deliver effective freshwater and Check, Clean, Dry advocacy, then contact us.

You too can become an advocate for protecting our freshwater resources by joining team Check, Clean, Dry. Ask one of the crew members to sign up to the Check, Clean, Dry pledge.

Ministry of Primary Industries' best cleaning methods for your gear and the latest information to prevent freshwater pests spreading.

Rangitīkei Environment Group

Horizons and Rangitīkei District Council work collaboratively with the Rangitīkei Environment Group (REG) to target Old Man's Beard.

REG carries out pest plant control (in particular targeting Old Man’s Beard) and biodiversity restoration works within the Rangitīkei District. The working group’s focus is to re-establish, enhance and sustain the native flora and fauna of the Rangitīkei District that is being degraded and destroyed by introduced exotic plant and animal pests.

Group of people standing around a car

Man holding a vine from a pest plant

Tutsan Action Group

Formed in Taumarunui in 2007 by Horizons, Department of Conservation, a local farm consultant and farmers concerned about increasing spread of tutsan in the Ruapehu District. Tutsan (Hypericum androsaemum) is a semi-evergreen shrub growing up to 1.5m tall with stalkless oval leaves opposite each other up to 100mm in length.

For more information visit, and

Weeding out Tutsan