Butterfly enthusiasts say a drop in the number of monarch butterflies this summer could be followed by population drops in other insects important to agriculture.
Monarch Butterfly Trust secretary Jacqui Knight says many people have reported seeing fewer of the distinctive butterflies in their gardens this year, especially in Canterbury.
Ms Knight says it could be because of the particularly hot, dry summer, but there may also be more concerning reasons, such as disease.
She says monarch butterflies are an indicator species and a drop-off in their numbers could signal a larger change in the eco-system.
Ms Knight says monarch butterfly numbers have also dropped in North America recently.