Lemon

This pale yellow butterfly is very common around here right now. I think it's a Lemon Migrant, Catopsilia pomona. 

In the extra, the butterfly has moved to an adjacent flower. Its proboscis can be seen extending deeply into the flower to extract nectar.

I photographed it in our garden, where it was feeding on the flower of a Metrosideros bush, which we bought as a potted plant about 4 years ago. It is a dwarf cultivar of New Zealand Christmas Tree, pohutukawa (Metrosideros excelsa). 

The botanical name was given by the Swedish botanist Daniel Solander, who sailed to the South Pacific with Captain James Cook and Joseph Banks on the Endeavour from 1768 to 1771. In early November 1769 they anchored in what Cook named Mercury Bay on the east coast of the North Island of New Zealand. The name was given to mark Cook's astronomical observation of the transit of Mercury on 9 November. Solander and Banks, as always, collected plants, including pohutukawa. I wonder if it was in flower at the time?

There is much interesting NZ botanical history in an online publication by WRB Oliver. Page 11 of this document refers to the collection of pohutukawa.