A Hamilton woman fascinated with butterflies has caught its budding transformation from caterpillar to chrysalis on video.
And butterfly experts say it's hard enough to witness the process let alone film it.
Mother-of-one Stacey Bell was at her Rototuna home when she spied one of the five caterpillars shacked up at her house begin to curl over as it dangled from the ceiling of her deck.
The grabbed her phone and began videoing its transformation into a cocoon over a 40-minute period.
She posted the video to a local Facebook page and it's been viewed 1300 times over the past three days.
"I'm very new to this and only bought my first swan plants three weeks ago. I'm having a bad time with them as I only had five and one caterpillar died while transforming into its chrysalis and another has been killed by a bird."
She saw three chrysalis transformations over the past three days.
Bell said she'd always had an interest in butterflies but her interest peaked recently after hearing monarch numbers were dwindling.
Monarch Butterfly New Zealand Trust chair Jacqui Knight said being able to watch the process, from caterpillar to chrysalis, was quite rare.
"I think it's an amazing thing to witness. You have to be lucky to see it because you sit and wait and wait and hope to see it and nothing happens and then suddenly the phone rings and you're distracted for two minutes and suddenly it's happened.
"I could swear that the caterpillars know that you're watching them."
Knight described watching the process as "life-changing".
The endangered forest ringlet butterly. Photo / Michael Reid
"It is rare [to watch] and people, when they see it, are amazed by it. It's actually life-changing watching it but you have to be in the right place at the perfect time."
The first sign that change was taking place was when the caterpillar turns into a J-shape, followed by it's "feelers" beginning to look withered and dry-looking.
"Then you know it's going to change within the next 30 to 60 minutes."
Meanwhile, Knight said senior English conservationist specialist Steve Wheatley is in the country to volunteer his time to study the forest ringlet butterfly, a species only found in New Zealand.
It appeared its numbers were declining and they hoped he could help pinpoint what's going on.
Wheatley arrived in the country last week, she said.
"It's being knocked back by something, we're not quite sure, that's what we're trying to find out - why it's disappearing from our landscape - because people aren't seeing it anymore."
The forest ringlet is about half the size of the more common monarch, but has similar colourings - featuring orange, black and silver stripes on its back and eye spots.
It lives in native forests from Northland to the top of the South Island.
