This article was published in The Fringe, February 2013
In previous articles I have mentioned puriri moths (Aenetus virescens) and admiral butterflies and how they are 'host dependent'. That is, they require specific plants at some stage of their life-cycle to survive.
The admirals lay their eggs on stinging nettle plants (Urtica species) and the puriri moth chooses a limited range of trees, including puriri and putaputaweta. The caterpillar of the puriri moth prefers these species to bore into and spends the bulk of its life, up to 5 years, in the well-concealed tunnels only to eventually hatch into our biggest butterfly with a wingspan of 15cm. Then, having mated and laid eggs, it dies a few days later.
But these are just 2 of the 20-30 butterfly species and thousands of moth species that call New Zealand home. They are special because most of them are endemic to New Zealand, occurring nowhere else in the world. Some are also interesting because they are particularly ancient and are the only living examples of families extinct elsewhere.
Many of our native Lepidoptera (i.e. moths and butterflies) have specific host plants that they could not live without.
The common shrub kawakawa (Macropiper excelsum) is readily recognised by the heart-shaped leaves generally being 'shot full of holes' due to chewing damage by a species of looper moth caterpillar (Cleora scriptaria). Kawakawa is not the only plant whose leaves are eaten by the caterpillar, but it is the preferred host, and the Cleora scriptaria is much the most common herbivore eating kawakawa. Interestingly, one insect that finds the kawakawa not to its liking is the maggot of the common house fly. You might think nothing short of an aerosol fly spray would kill maggots, but the complex chemical defences produced by kawakawa are so efficient the leaves are, in fact, toxic to maggots. Which, of course, gives added respect to the Cleora caterpillar that thrives on a diet of kawakawa.
And that is where we come into the BIG picture in the 21st century.
We must attempt to keep it all in balance, keeping healthy examples of every type of habitat.
Your backyard is the place to start encouraging the full complement of species for the type of habitat that you have chosen to live with.
There is certainly a ragged little moth out there desperate for your help.
Learn to love it.
For more about NZ moths and butterflies go to www.monarch.org.nz
Their Conference at Unitec, Mt Albert, Auckland, is set down for 16 and 17 March 2013.
Beever, R.E. 1987. 'The holes in the leaves of kawakawa (Macropiper excelsum).'
Auckland Botanical Society Newsletter 42: 9-11.