The Deadliest Caterpillar On The Planet – Lonomia obliqua

You may be familiar with the children’s book ‘The Very Hungry Caterpillar’ by Eric Carle. It’s the innocent tale of a hungry caterpillar who eats his way through the week. Another caterpillar, Lonomia obliqua, is nothing like that. In fact Lonomia obliqua is the deadliest caterpillar in the world.


Nestled within the rainforests of South America is possibly the world’s deadliest caterpillar; the Lonomia obliqua, whose venom can be fatal to humans. Before growing into a giant silkworm moth in the later stages of its life, the larval caterpillar lies hidden away in the forest, blending into the trees with its mottled green and brown colours – and bristling with hollow hairs that can puncture the skin of a grown man and inject a flow of deadly toxins.

Stored in sacks that rest at the base of each spine, the venom contains a powerful anti-clotting agent that can lead to severe internal bleeding. This bleeding can spread to other organs and eventually the brain, causing death. The good news? Most humans would likely need to be stung anywhere from 20 to 100 times for the toxins to be delivered in a dose that would be fatal.

Poisonous Caterpillars

Even so, it’s thought that the caterpillar accounts for as many as 500 deaths throughout South America, with the tiny creature – averaging around 2 inches in length – first coming to prominence during an outbreak of strange symptoms relating to internal bleeding in Rio Grande do Sul, in Brazil. Further investigation found the main link to be that all patients had worked through the rainforest, with the Lonomia obliqua the only common creature that could have caused the injuries through accidental contact.

Band Meeting? No, the correct term for a group of caterpillars is an 'Army'. Consider yourself educated. (Photo: Wikimedia/Centro de Informações Toxicológicas de Santa Catarina)
Band Meeting? No, the correct term for a group of caterpillars is an ‘Army’. Consider yourself educated. (Photo: Wikimedia/Centro de Informações Toxicológicas de Santa Catarina)

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Despite the caterpillar’s apparent spread throughout Brazil, Paraguay, Uruguay and Argentina, there’s a upside to the proliferation of the creature’s lethal toxins. Studies have found there may be potential medical applications linked to the venom’s effect on blood and cells. In addition, an anti-serum for the venom created in Sao Paulo has been shown to swiftly restore patients to health.

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Want to avoid personally being a part of these ongoing medical trials? Wear gloves? Or simply avoid brushing your way barehanded through the rainforests and lounging against the trees where the world’s deadliest caterpillar rests.

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