Plant Doctor Archive

Where do the monarchs go?

IS there any reason why the seed pods on my swan plant were ball-shaped this year rather than swan-shaped as last year? And where do monarch butterflies go in winter? I saw one flying around last week so they must have liked our mild winter.

IT'S quite common for seed pods on swan plants to change shape, but I don't know why. I suspect changes in environmental conditions such as temperature, drought or fertiliser affect their development.

Monarch butterflies in New Zealand don't seem to migrate over great distances as they do in North America. Studies here suggest the furthest they're likely to go is around 20km and most travel a lot less. In autumn, as the weather gets cold, several thousand butterflies can cluster in warm, sheltered spots, often within the branches of a large evergreen tree. Those I've seen were well hidden inside large conifers, protected from the worst of the winter wind and cold. On warm winter days some of the butterflies fly out from the cluster to feed on nectar from nearby flowers, so several monarchs flying around near large trees in winter may be a clue to the large cluster within.

Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.