Christine Haar, of Gore, asks :-
I have been growing stinging nettle for admira butterflies. So far I have hatched and released 52 yellow admirals but to my great disappointment no red admirals. Do they not lay eggs on the same nettles if the yellow admirals have laid there first or am I growing the wrong type of nettle to encourage the red admiral?
Brian Patrick, an entomologist with Wildland Consultants and co-author (with his son) of the book "Butterflies of the South Pacific (2012)", responded.
New Zealand is a global hotspot for admiral butterflies with three attractive species, two having overlapping distributions, as follows.
The NZ red admiral (Vanessa gonerilla) is endemic to NZ as breeding species. It is widespread over the three main islands but with one record of it straying as far as Macquarie Island - an Australian territory in the subantarctic. Its larvae feed on most indigenous nettles plus exotic species but prefer indigenous species
The Chatham Is red admiral (Vanessa ida) is endemic to the Chatham Island group where it feeds on a tall local indigenous nettle
The Yellow admiral (Vanessa itea) occurs in eastern Australia and the three main islands of NZ. Its larvae are on exotic nettles only. It probably evolved in Australia and is a fairly recent immigrant to NZ. Now it is common in backyards and farmed areas.
As you can see the NZ red admiral prefers our suite of native nettles whereas the more recent yellow admiral prefers the introduced weedy species. Red admiral larvae do feed on the introduced species but not quite to the same extent as the yellow admiral. If you find groves of our large tree nettle or herbfields of our mountain nettle, you will likely find red admiral larvae common living in shelters of silk-joined leaves. It is quite a sight to discover them.
Unfortunately some introduced parasitoid wasps (parasitoids kill their host in contrast to parasites which mostly weaken), introduced as part of biological control programmes for other species, now attack red admiral pupae, often decimating the local population. So much so that now red admirals are uncommon in many parts of the country.
Interestingly the other nine admiral butterflies are found as follows; Europe - North America - North Africa - western and Central Asia (one species) India to Japan (one species) Canary Islands (one species) Hawai'i (one species) Indonesia - Sumatra & West Timor (two species - one each) Philippines to parts of Indonesia (one species) Southern Africa (one species) East Africa (one species)
Just about everywhere appears to have a local admiral butterfly, but nowhere but on the three main islands of NZ are two found naturally together. By leaving a "wild corner" in our gardens for nettles to thrive we are recognising that our admirals, not only are attractive inhabitants on our landscape but an important part of our biodiversity.