This notorious spider is a dark, velvet-coloured creature about 25 mm in span and is characterised by its large globular abdomen – about the size of a pea – with an orange or red stripe down the middle. It is identical or closely related to the common Australian red-back or jockey spider, and to the black widow spider of America. It is not particularly common but where it does occur it can be found in numbers. It occurs northwards of Banks Peninsula, and favoured localities are coastal sand dunes and beaches. If present in such places, it can be found during the day under stones and driftwood and in sheltered parts of plants. It has been observed in numbers on the beaches in the vicinity of Foxton, Wanganui, the west coast of Auckland, and on the raised beaches around the Wellington coastline, but it could be expected to occur over most of the coastline of the North Island and the northern part of the South Island.
The bite of the katipo can be fatal and deaths have occurred in New Zealand from its effects. Australian records show that six cases were fatal out of 98 instances of attack. The bite causes agonising pain that develops and spreads within a few minutes. This is often accompanied by profuse sweating, difficulty in breathing, vomiting, convulsions, and other effects. The poison is particularly virulent but the degree of effect from a bite is probably directly related to the amount of poison injected into the bite wound.
by Roy Alexander Harrison, D.SC., Senior Lecturer in Agricultural Zoology, Lincoln Agricultural College.