The most poisonous animals and plants in New Zealand

Ask most visitors what they know about New Zealand wildlife and you get some version of the same question. Is it like Australia? The short answer is no. There are no snakes, no scorpions, and exactly one venomous native spider, which has not credibly killed anyone in more than a century and is now rarer than the kiwi.

The longer answer is more interesting. The things that actually poison New Zealanders are not in the undergrowth of a nature documentary. They are in the vegetable patch, the flower bed, the bush track and the honey jar. And the one venomous animal that reliably kills people here is not a spider at all.

Here is what the evidence actually says, ranked by the only measure that matters, which is what happens to real people.

Poisonous and venomous are not the same thing

Almost every “dangerous animals in New Zealand” list online muddles these two words, which is why they all reach the wrong answer.

• Poisonous means it harms you when you eat it, or absorb it through skin or eyes. The poison is passive. You have to go to it.
• Venomous means it injects a toxin into you through a fang, sting, spine or hair. The animal or plant delivers it. It comes to you.

Toxin is the umbrella word. Poison and venom are just two delivery routes for one. The distinction matters here more than almost anywhere, because New Zealand is close to empty of venomous animals and quietly full of poisonous plants. Ask which is worse and you are asking the wrong question. Ask what people actually swallow, touch and walk into, and the answer changes completely.

What New Zealanders actually ring the Poisons Centre about

New Zealand has one national poisons hotline, and it keeps records. That makes it the only honest scoreboard we have.

Toxicologists at the National Poisons Centre went through eight years of it. In a review published in the New Zealand Medical Journal in December 2012, Robin Slaughter and colleagues analysed every plant exposure call from 2003 to 2010. The centre took 256,969 enquiries over those eight years. Of those, 171,130 involved someone actually being exposed to something, and 11,049 of those, or 6.5 per cent, involved plants and fungi. That is around 1,381 plant and fungi calls a year.

The fifteen most-reported plants accounted for 2,754 of those calls, about a quarter of the total. Here they are, in the order New Zealanders actually rang about them.

#	Plant	Calls	Children
1	Black nightshade	834	90%
2	Arum lily	556	94%
3	Kōwhai	155	88%
4	Euphorbia	149	24%
5	Peace lily	144	99%
6	Agapanthus	136	79%
7	Stinking iris	128	96%
8	Rhubarb	121	76%
9	Taro	95	56%
10	Daffodil	84	67%
11	Oleander	81	53%
12	Hemlock	77	51%
13	Karaka	69	88%
14	Ongaonga	64	8%
15	Foxglove	61	74%

Look at what is not there. No tutu. Karaka is thirteenth. Ongaonga is fourteenth. The plants with the fearsome reputations are at the bottom of the list, and the top of it is a weed and a garden flower.

A few things fall out of that table that are worth saying plainly. Black nightshade and arum lily between them account for just over half of all fifteen plants’ calls. Black nightshade alone generated a call every three and a half days, for eight years straight. And a peace lily, the office pot plant, produced more calls than both of the native plants known to have killed a New Zealander put together.

Four out of five of those calls were about a child under twelve. In a separate analysis of the centre’s 25,330 phone calls in 2018, 50.3 per cent were down to a child exploring, 50.3 per cent involved someone aged nought to four, and 74.3 per cent could be handled at home without going near a hospital.

So “most poisonous” splits into three different questions, and they have three different answers. What poisons the most people? What is most toxic? And what has actually killed someone? Take them in turn.

Black nightshade and arum lily, the plants behind most calls

Black nightshade is a common weed, and it fruits little green berries that ripen to dull black. Arum lily is the white trumpet flower in half the gardens in the country. Neither is exotic or dramatic. Both are exactly where small children are, at exactly the height small children are.

The route data makes the point. Across all fifteen plants, 86 per cent of exposures were someone eating the thing. For black nightshade it was 778 of 834 calls. For arum lily, 525 of 556. For peace lily, 142 of 144. And 143 of those 144 peace lily calls were about a child, which is the highest proportion of any plant on the list.

Only two plants in the whole table were reported more often by adults than children, and they are the two you meet standing up. Euphorbia is 76 per cent adults, and 104 of its 149 calls were eye exposures, because people prune it and then rub their face with a sappy glove. Ongaonga is 92 per cent adults, and 60 of its 64 calls were skin contact, because people walk into it.

That is the shape of plant poisoning in New Zealand. Children eat things at ground level. Adults get sap in their eye or walk into a nettle. Almost nobody is doing anything exotic.

Ongaonga, the tree nettle that has killed

Plant and fungal poisoning puts about 75 New Zealanders in hospital a year, and kills almost none of them. Only two native plants are known to have killed anyone by poisoning at all, according to Te Ara, the Encyclopedia of New Zealand. One is tutu. The other is ongaonga, the tree nettle, and it is the plant that most deserves the reputation the katipō gets.

Urtica ferox grows to two metres or more in coastal and regenerating shrubland, and it can form dense thickets. Its leaves and stems carry stinging hairs called trichomes, up to six millimetres long. They are not an irritant coating. They are hypodermic needles. Brush against one and the tip snaps off to leave a needle point, the bulb at the base compresses, and the fluid inside is pushed through the tube into your skin. Ongaonga does not poison you. It injects you, which makes it closer to a sting than to contact poisoning, and blurs the neat line drawn at the top of this article.

On Boxing Day 1961 two young men hunting in the Ruahine Range walked through a patch of it and were stung on the limbs. Within an hour one of them could not walk properly and was struggling to breathe. Then he lost his sight. He died five hours later in hospital. His companion had the same symptoms and recovered.

Te Ara, written in 2009, records that as the only fatal case. There may be a second, and the story of how it surfaced is a strange one.

In December 2002 a 25-year-old shearer named Jason Chase left Gisborne to drive home to Dannevirke for Christmas and never arrived. His car turned up at the Tamaki Reserve in the Ruahine foothills. His body was found on 3 January 2003. There was no injury, no sign of foul play, and nothing in the toxicology. The cause of death went down as obscure natural causes, and stayed that way for fifteen years.

The pathologist who could not explain it, Cynric Temple-Camp of Palmerston North, later changed his mind. In his 2020 book The Quick and the Dead he argued that Chase had walked into tree nettle, and that the 1961 death in the same range was the precedent nobody had connected. He told the Herald on Sunday he was “quite sure that was the only plausible explanation”.

That is one pathologist’s retrospective conclusion in a popular book, not a coroner’s finding, and it was reached long after any toxicology could have settled it. It is worth reporting for what it would mean if he is right. Ongaonga would have killed a man within living memory, and it took fifteen years for anyone to suggest it.

For most people a sting means intense pain, itching and inflammation lasting 12 to 36 hours or longer. Bigger exposures can bring on stomach pain, blurred vision, weakness, loss of co-ordination and, rarely, paralysis. For decades the active ingredients were listed as acetylcholine, histamine and serotonin, with a suspicion that something else was in there too. That suspicion turned out to be right. In 2022 a New Zealand and Australian team published the answer in the Journal of Biological Chemistry. They isolated two peptides, Δ-Uf1a and β/δ-Uf2a. The second is a potent activator of the voltage-gated sodium channels that carry nerve signals. Ongaonga, in other words, has a genuine peptide neurotoxin, of the kind you would expect from an animal rather than a shrub.

Tutu, tutin and New Zealand’s toxic honey problem

Tutu (Coriaria arborea) is the other native killer, and it produces the strangest poisoning story in the country.

It grows throughout New Zealand on bush margins and beside streams. Every part of it is poisonous except the swollen petals. New Zealand chemists identified the toxin, tutin, around 1900. It acts on the central nervous system and causes convulsions and breathing trouble. Human poisonings have been rare since then, though Te Ara records that one man died in 1989.

The unusual part is how it reaches people, because it is not by eating the plant. Bees do not take tutin from tutu nectar or pollen, neither of which contains it. A sap-sucking insect called the passion vine hopper feeds on the tutu, excretes honeydew, and bees collect the honeydew. The poison arrives in the hive by a three-species relay.

In March 2008 that relay put 22 people in the medical system in Whangamata on the Coromandel, some of them seriously ill in hospital, after they ate local comb honey collected that January. The outbreak report in the New Zealand Medical Journal records tutin in the honey at 30 to 50 milligrams per kilogram. Nobody spotted it until three members of one family arrived at hospital and someone noticed they had all eaten the same honey.

The Ministry for Primary Industries now caps tutin in honey at 0.7 milligrams per kilogram. The 2008 honey was more than forty times that limit. The risk window runs January to April, across most of the North Island and the top third of the South Island, and it is the reason commercial honey gets tested. It is also a good argument against eating untested comb honey from a roadside stall in late summer.

Karaka berries and plant identification apps

Karaka is a native tree with glossy leaves and bright orange fruit, and every one of the 69 calls about it in the Poisons Centre data was someone eating it. Not one was skin or eye contact. It is the only plant in the fifteen with a perfect score on a single route.

The danger is in the kernel, which contains karakin. Karakin breaks down into 3-nitropropionic acid, which shuts down succinate dehydrogenase, an enzyme your mitochondria need to make energy. Poisoning starts with vomiting and stomach pain and, in bad cases, can cause lasting neurological damage.

Karaka was also a staple food. Māori made the kernels safe by cooking them and then washing them in running water for long enough to leach the toxin out, a preparation that turns a dangerous seed into a storable food. That is not folklore. It is empirical food chemistry worked out and reliably transmitted across generations, and the fact that the Poisons Centre still fields calls about karaka is a reminder of how much knowledge sits behind it.

Which brings us to a recent finding that matters more than any of the folklore. At the Toxicology and Poisons Network Australasia assembly in Wellington in 2025, a team including Poisons Centre researcher Robin Slaughter reported on how well phone apps identify New Zealand plants. Unidentified plants made up 12 per cent of the centre’s plant calls in 2023, so this matters.

They photographed the top 20 plants and top 8 native plants the centre gets calls about, 457 photos in all, and ran them through four tools. Pl@ntNet did best at 93 to 94 per cent. Google Lens managed 90 per cent. But native plants scored worse across the board, and on karaka berries specifically, one of the seven highest-toxicity plants in the study, the iPhone’s built-in Visual Lookup scored zero per cent. Seek by iNaturalist managed zero on iPhone and 40 per cent on Samsung.

Your phone cannot reliably identify one of the most toxic berries a New Zealand child is likely to put in their mouth. Do not let it tell you something is safe.

Death cap mushrooms and the false recovery phase

The death cap (Amanita phalloides) is introduced, not native, and grows in association with oak and chestnut in Auckland, Waikato, Bay of Plenty, East Cape, Whanganui and Nelson. It causes roughly 90 per cent of fatal mushroom poisonings worldwide.

Its toxins are amatoxins, chiefly α-amanitin, which block RNA polymerase II and so stop cells making protein. The liver takes the worst of it, then the kidneys.

The cruel part is the timing, and it is worth understanding properly. Nothing happens for six to 24 hours. Then come violent vomiting, diarrhoea and cramps. Then, after a day or so, the patient feels better. That apparent recovery is not recovery. It is the liver being destroyed quietly, and organ failure follows from around 72 hours. Anyone who eats a suspected death cap needs medical help during the phase when they feel fine, not when they feel ill again.

New Zealanders have historically not foraged much, so serious cases are rare. They are not absent. Te Ara records a case in June 2005 where a recent immigrant became critically ill after eating cooked death caps. A Waikato doctor was left with permanent liver and kidney damage after eating a foraged one in 2020. And when Poisons Centre toxicologists were asked for specialist advice on non-medicine exposures between 2018 and 2020, unidentified mushrooms were the single largest category, 66 of 1,185 cases.

The grey side-gilled sea slug, New Zealand’s most toxic animal

If “most poisonous” means most toxic per gram, the winner is an animal almost nobody names, and it is not a spider.

In August 2009 dogs started dying on beaches around the Hauraki Gulf. The Cawthron Institute traced it to the grey side-gilled sea slug, Pleurobranchaea maculata, and found it was loaded with tetrodotoxin. It was the first time the toxin had been found in New Zealand and, as far as anyone knew, the first time it had been recorded in a soft-bodied sea slug anywhere. The measurements, published in Toxicon in 2010, ran from 91 to 850 milligrams per kilogram, with a median of 365.

Tetrodotoxin is the same toxin that makes pufferfish and the blue-ringed octopus dangerous. It blocks the voltage-gated sodium channels your nerves use to fire, which paralyses muscle, including the diaphragm. There is no antidote. Treatment is keeping the patient breathing until it wears off. The slug almost certainly does not make it. Like the pufferfish, it appears to accumulate it from bacteria through its diet.

And yet it has never killed a person in New Zealand. It killed dogs, because dogs eat whatever is on the beach and people do not eat sea slugs.

That is the idea the danger lists miss. Toxicity is not danger. Danger is toxicity multiplied by exposure. The most poisonous animal in the country is harmless to you because you will never eat one, while a garden weed you have never worried about generates a Poisons Centre call every three and a half days.

Katipō, New Zealand’s only native venomous spider

The katipō does not appear anywhere in the Poisons Centre’s most-reported list, which tells you most of what you need to know.

Latrodectus katipo takes its name from the Māori for night-stinger. Only the adult female bites, and a full-grown one is about the size of a garden pea, black with a red stripe. It lives in sand dunes, it is shy, and it generally only bites if you squash it. As the arachnologist Simon Pollard puts it in Te Ara, there is no solid evidence anyone has died from a katipō bite in the last hundred years. Reports of a 1901 death circulate, but even those are disputed, and there is no confirmed death in a modern medical setting.

A bite causes latrodectism, which is genuinely unpleasant. Pain spreading from the bite, sweating, muscle rigidity, nausea. Antivenom exists, developed in Australia for the redback and effective here.

The real story is the reversal. The katipō is now a threatened species. It is illegal to collect or kill one. Its dunes have been taken over by marram grass at the expense of native pīngao, and experts consider it rarer than the kiwi. New Zealand’s most feared spider needs protecting from us, not the other way round.

Redbacks, white-tails and the necrosis myth

Two Australian spiders have also set up here, and the story is much the same as the katipō’s.

The redback (Latrodectus hasselti) is the katipō’s close cousin and responds to the same antivenom. It likes dry sheltered spots and turns up in outbuildings, in small localised populations. New Zealand’s damp climate does not suit it.

The white-tailed spider is the interesting one, because it is the subject of the most durable wildlife myth in the country. Two Lampona species have been here for at least a century, living in cracks and crevices. And more or less everyone believes their bite rots your flesh.

It does not. In 2003 the toxinologist Geoff Isbister and arachnologist Mike Gray ran the study that should have ended this. They followed 130 confirmed white-tail bites in Australia, where each spider was caught and formally identified by an arachnologist rather than guessed at. Necrotic ulcers in 130 bites: zero. None. Te Ara notes that 75 per cent of those bitten said it hurt less than a bee sting. It was Australian research rather than New Zealand research, but they are the same spiders.

When someone does develop an ulcer, the cause is generally a bacterial infection or an existing skin condition. The spider gets blamed because it was in the room.

Wasps and bees, the venomous animals that actually kill New Zealanders

Here is the answer none of the danger lists give.

A review of coronial autopsies in Auckland between 1985 and 2005 found 18 deaths from anaphylaxis. Four of them were caused by bee or wasp venom. Across those same twenty years no one in New Zealand was confirmed killed by a spider, and nobody has been in more than a century. The venomous animal most likely to kill you here is the one at the summer barbecue.

It is not the toxin doing it. A wasp sting is painful but a long way from lethal. What kills is anaphylaxis, an immune overreaction in people who are allergic, and that is why the danger is unpredictable and personal rather than a property of the animal.

There are also a great many wasps here. The Department of Conservation and Manaaki Whenua Landcare Research both put New Zealand’s German and common wasp densities among the highest in the world. The German wasp arrived near Hamilton in 1945, the common wasp was first found in 1978, and neither has any natural enemy here. In the honeydew beech forests of the northern South Island, wasps reach the highest densities recorded anywhere. Ecologist Jacqueline Beggs measured a peak of about 3.8 kilograms of wasps per hectare, roughly 10,000 workers, stripping more than 90 per cent of the honeydew for five months of the year. Their biomass in those forests exceeds that of all the native birds combined.

New Zealand is now working to keep the next one out. Biosecurity teams have spent months trying to eradicate the yellow-legged hornet from Auckland, an insect that would make the existing problem considerably worse.

None of this is a reason to be frightened of a picnic. If you know you react badly to stings, carry what your doctor has prescribed and make sure someone with you knows where it is. That is the entire precaution.

Sharks, sea snakes and the blue-ringed octopus

Almost every list of New Zealand’s most dangerous animals is written offshore, and it shows. They tend to be describing Australia.

• Sharks are neither poisonous nor venomous. They appear on these lists because the lists were never really about poison.
• The blue-ringed octopus is a tropical species whose range runs from Japan to southern Australia. New Zealand has 42 species of octopus and this is not one of the ones you will meet in a rock pool.
• Sea snakes have no resident, breeding population here. They are not fictional, though. Yellow-bellied sea snakes drift down on warm currents and strand on beaches, and Newswire has reported several, including two washing up in the Bay of Plenty inside a week in May 2026. They are venomous and protected. Leave them alone and tell DOC.
• Bluebottles are a fair inclusion, unlike the octopus. They blow ashore most summers and they sting.
• Shellfish get left off entirely, which is the strangest omission of all. Toxic algal blooms load shellfish with saxitoxin, which blocks the same nerve channels tetrodotoxin does, and it triggers public health warnings and gathering bans somewhere in the country most years. In July 2026 the warning covered the Marlborough Sounds from Tennyson Inlet to Fitzroy Bay. Check for a current warning before you gather anything.

The pattern is consistent. The lists rank by how frightening an animal looks in a photograph. The Poisons Centre ranks by who rang up.

What to do if you think someone has been poisoned

1. Ring the National Poisons Centre on 0800 764 766. Free, 24 hours, staffed by toxicologists. Ring before symptoms appear, not after. Three quarters of cases are managed at home.
2. Ring 111 first if they are seriously unwell. Drowsiness, breathing trouble, seizures or unconsciousness mean an ambulance, not a phone consult.
3. Keep a sample. A leaf, a berry, the mushroom. Accurate identification changes the risk assessment completely, and a photograph of the whole plant helps.
4. Do not use an app to decide something is safe. They are useful for narrowing things down and unreliable exactly where it counts, on native plants, as the karaka result shows.
5. Do not wait for a false recovery. With death cap in particular, feeling better after a day is part of the illness, not the end of it.

The most poisonous things in New Zealand, ranked

So what are the most poisonous things in New Zealand? It depends which question you meant, and each has a different answer.

• Most reported: black nightshade, a weed, followed by the arum lily in your garden.
• Most toxic: the grey side-gilled sea slug, which has never harmed a person here.
• Actually killed someone: ongaonga and tutu, the only two natives with a body count, plus death cap mushrooms and tutin honey.
• Most likely to kill you: a wasp or a bee, if you happen to be allergic.

Not one of those is the spider on the tourist posters. New Zealand’s most poisonous things are a nettle, a weed, a honey contaminant and a sea slug nobody has heard of. And the country’s most notorious venomous animal, the katipō, is now so rare it needs a conservation programme.

Which of these surprised you most, and has anyone in your family ever had a run-in with ongaonga or a wasp nest? Tell us in the comments.

This article was written by AI, briefed to report the facts, hopefully without some of the bias people bring to the job 🙂