Christchurch parks are being sprinkled with orange clusters of monarch butterflies.

Over the colder months the insects form clusters, sometimes containing hundreds or even thousands of butterflies on trees or other sheltered areas to keep themselves warm.

Christchurch City Council Regional Parks Manager Kay Holder said there's already been sightings at St James Park, Abberley Park, the Pioneer Recreation Centre playground, Linwood Cemetery and Woodham Park.

"This time of the year is when you see the main numbers in the fall, and then depending on what type of winter we have, as to how many survive over winter."

Kay Holder said anyone wanting to know the best spots to see the butterflies should head to the Monarch Butterfly New Zealand Trust website or the council's Facebook page.