On Thursday, students at Burnside Primary will collect boulder copper butterflies from McLeans Island and bring them back into the city.
Numbers have rapidly declined and they are now found only sparingly in a few locations across Canterbury.
The species, endemic to New Zealand, will be moved to a school garden specially designed for the creatures to thrive.
Canterbury "bug man" Ruud Kleinpaste said the butterfly has not inhabited Christchurch for around 200 years.
"People have been building houses and suburbs in the right place where the butterfly likes to live so it had to retreat."
"The kids of Burnside Primary have decided it's time the boulder copper butterfly came back."
A special Mihi Whakatau, with local iwi members, will also be held to welcome the butterfly back.
Throughout the year, the students will study the butterflies' progress, making decisions to improve and create a larger butterfly garden area.
The group will work with organisations such as Trees For Canterbury to identify, grow and maintain endemic plants needed for the boulder copper.
They have already been working with Isaac Construction, which donated the soil and rocks needed.