The idea is the where the butterflies travel to can be monitored.
When the butterflies at St Mary's School in Rotorua fly away in winter, there's still a chance for the pupils to follow their journey.
The school has taken part in a butterfly tagging project this year to paint a better picture of where they go in the winter.
Tagging involvesplacing a small sticker, with a unique number, on a specific spot on a butterfly.
The sticker uses special glue and its unique number is recorded online.
If a tagged butterfly is spotted, the person who spots it is encouraged to report the sighting at mb.org.nz, painting a picture of where monarch butterflies in New Zealand travel in the winter.
Bach said the project was beneficial in more ways than one.
"The whole aim was to tag monarch butterflies but there are a lot of offshoots.
"Lots of other bugs have come in like beetles, praying mantis, and the school has started a bug club."
Bach said he hoped to hand the project over to the pupils as much as possible.
"They look at the life cycle of the monarch butterfly. It's like an animal study. They record data and look for evidence. Science is not just learning information."
Thornton Smart, 9, liked watching the butterflies grow, from eggs to caterpillars, chrysalis and finally to a butterfly.
"It's fun because we get to run around when it's tagging season and catch them.
"There wasn't anything in this area of the school till this year. Now the butterfly enclosure is here and everyone has come around."
The idea originated in North America where monarch butterflies tagged in the United States and Canada were found to have migrated to Mexico City.
In New Zealand the project is co-ordinated by the Monarch Butterfly Trust.
