New Zealand campers frequently burn kawakawa leaves to ward off pesky insects.

Now a young scientist is developing the plant's properties into a bug repellent.

Palmerston North Intermediate Normal pupil Zoe Glentworth, 12, won the prize for best technology entry at the weekend's Science and Technology Fair, held at Te Manawa.

Zoe developed a balm made from kawakawa leaves and is working on a bug spray also using the plant's repelling properties, which she tested on a container full of flies.

"Maori used to chew it up and rub it on their skin," she said.

That knowledge helped her come up with the winning idea, for which she received $700. She plans to bank the money.

Now Zoe is looking to develop her product further, and is thinking about how much she could charge for a jar of balm.

"It could make a really good business. I worked out the figures . . . and we'd make $2.54 profit if we sold it for $10.

"Someone said to me, ‘You should put $10 more profit and you'd make quite a lot'."

A spray might cost more, but would be more popular, Zoe said.

The project took about three months from start to finish.

Zoe thanked her parents and the Herb Farm's Lynn Kirkland for their help.

Alex Johnston, of Ross Intermediate, won the best science prize for his project that looked at mason wasps.

The competition is open to all school-age pupils in the region, up until year 13.

There were 189 entrants in the science and technology sections, as well as 40 in the photography and art section.

- © Fairfax NZ News