The Monarch Butterfly New Zealand Trust is being inundated with requests for help with starving monarch caterpillars.
“This happens every year,” says Jacqui Knight, Secretary of the Trust. “But this year the pleas have started much
earlier, for a range of reasons.”
Swan plants (Gomphocarpus fruticosus, and G. physocarpus) are the main milkweed species used in NZ as host plants for monarch butterflies (Danaus plexippus).
The cold, wet winter caused many larger plants to die out. Otherwise they would have fed caterpillars over two or three
seasons. The weather also provided just the right conditions for slug and snail populations to soar – and molluscs are
particularly partial to swan plants, eating the new foliage and also ring-barking the trunks.
“The only plants available this year in garden centres are a few months old,” she added. “They don’t last very long.”
The Trust’s advice is, when buying plants, buy twice as many and keep half of them covered up. Use them later in the
season, when they’re a better size. Do not throw away the defoliated stems, either: feed them well and they will recover
with new leaves.
“People could also feed larger caterpillars (over 3 cm long) on pumpkin or a pest plant, moth vine (Araujia sericifera). Those are not ideal and some butterflies emerge deformed, but it’s making the best of a bad thing. Or leave it to
She said that New Zealanders have a love affair with monarch butterflies.
“From what I have seen from my travels, New Zealanders have more respect for these beautiful butterflies than anywhere