Distribution of clover root weevil
Clover root weevil is very widespread in the Northern Hemisphere, including all of Europe and North America.
North Island
CRW was discovered in Auckland and Waikato in 1996 and has since spread throughout the North Island, advancing approximately 35 kms per year.
South Island
CRW was first discovered in the South Island in late January 2006 when a single CRW was caught in an experimental trap at Christchurch International Airport. Extensive sampling of nearby pastures in the following month found only two more CRW out of several thousand other weevils collected. In April 2006, a much bigger and more firmly established population was discovered at Richmond, near Nelson, and soon after it was also confirmed at Rai Valley.
CRW has now been detected in the South Island at various locations in upper Takaka Valley, Richmond, Rai Valley, Blenheim, Canterbury (many places around Christchurch and one site near Ashburton) and Otago. Most of the CRW populations found in these localities currently occur at fairly low population densities and appear to have become established only recently. Relatively high population densities of CRW have been found only at Richmond and Rai Valley (both in 2006) and more lately in upper Takaka Valley and Blenheim (both in December 2008), and at one site in Canterbury (June 2008). A single CRW was collected from pasture near Clinton in Otago (January 2009), and several CRW have recently been found near Mosgiel (January 2010). Please inform AgResearch as soon as possible if you think you have seen evidence of it somewhere else!
The CRW parasitoid is now well established in Nelson-Marlborough (marked by yellow triangles on the map below), and has recently been released in Golden Bay and North Canterbury (black triangles).
