It is suspected a foreign beetle which has been found in Auckland probably hitchhiked its way to New Zealand.

More than 50 hadda beetles have been discovered in Dove-Myer Robinson Park, the Auckland Domain and along Tamaki Drive.

The Ministry of Agriculture and Forestry's biosecurity response manager David Yard says the beetle can cause damage to potato and tomato crops. He says it is not clear where the insects came from.

"They are widely distributed in most other counties, across the Pacific and Asia. It is quite likely they've come in as a hitchhiker across the port on a container, probably, or in a container."

Mr Yard says after MAF has finished spraying the known colonies with insecticide it will carry out a survey to find out how far the beetles have spread.