Story: Spiders and other arachnids
Page 5 – Poisonous spiders
New Zealand has no harmful animals like poisonous snakes, scorpions or venomous insects, so its sole poisonous native spider – the rare katipō – has almost mythical status. Since the late 19th century there have been accidental introductions of the poisonous redback and white-tailed spiders from Australia.
Māori knew of a poisonous spider that lived on or near some of the warmer North Island beaches. They called it the katipō, which means ‘night-stinger’. The scientific name is Latrodectus katipo.
Only the adult female katipō bites. A fully-grown female is about the size of a garden pea. It is black, with a bright red stripe on its back.
Katipō are naturally shy, and would probably only bite if accidentally squashed. Few New Zealanders have ever seen one, let alone been bitten. Despite their reputation, there is no solid evidence that anyone has died from a katipō bite in the last 100 years.
Rarer than a kiwi
Katipō spiders are now classified as a threatened species. It is illegal to collect or deliberately kill them. The decline is probably because of changes in the beach habitat, especially the replacement of native pīngao with marram grass. Experts agree that there are now fewer katipō than another national icon, the kiwi.
In recent years small numbers of the Australian redback spider (Latrodectus hasselti) have been recorded in different parts of New Zealand. Because it prefers dry sheltered places, it is often found in outbuildings. There appear to be only small, localised populations, but there is some possibility of the spider spreading further through much of the North Island and northern parts of the South Island. While New Zealand’s damper climate does not favour the redback, their liking for modified urban environments could provide shelter from the weather.
Two species of the Australian white-tailed spider, Lampona cyclindrata and Lampona murina, have been recorded in New Zealand, and appear to have been present for at least 100 years. Both live in cracks and crevices, sometimes on the outside of houses.
The bite of the white-tailed spider is not poisonous to humans. There has been considerable publicity about serious skin infections, called necrotic lesions, that may develop near bites. In a recent Australian study of 130 confirmed white-tailed spider bites, 75% of people said the bite was less painful than a bee sting, and nobody developed lesions.