Christine Haar, of Gore, asks :-
I love raising Monarchs and this year I have had around 200 caterpillars sent to me from up north. They have all hatched into butterflies. Some of these are just starting to lay again now. Do you think this lot has a chance of surviving our winter, or will they migrate north. If they do migrate what are my chances they come back in Spring? If I was to try and keep the butterflies alive inside for winter what would the best recipe be for nectar and would this be possible? I would so love to have my own stock to start off in Spring with rather than trying to get caterpillars sent to me.
Brian Patrick, an entomologist with Wildland Consultants and co-author (with his son) of the book "Butterflies of the South Pacific (2012)", responded.
What a superb effort Christine in raising and releasing so many monarchs in Southland. That will be a huge boost for the local population. I was also raised down south, in Invercargill, and never saw a monarch in the wild there till the 1990s, although they were being bred in the botanic gardens glasshouse in Queens Park, as early as 1969.
Your monarchs will find a suitable over-wintering place in the Gore area. There is recent evidence from Earthlore, near Owaka of over-wintering monarchs in The Catlins, so yours will do the same. Keep a look out for them flying on the warmest winter days in places with lots of tall trees.
These over-wintering butterflies will mate in the spring and begin looking for foodplant on which to lay their eggs, so it is crucial to have plants available for them early in the season.
I suggest not attempting to keep them in-doors over the winter. It is too difficult and ultimately not the natural way to boost the local population. Set them free and then actively search for their over-wintering places. That will be much more satisfying.