The Nairobi fly does not bite or sting, yet it can cause severe chemical burns.

Nature · Published 3 October 2026 Swipe more like this →

In short: Known as the Nairobi fly or dragon bug, this East African rove beetle is harmless until crushed. It carries a potent toxin called pederin in its haemolymph, which triggers blistering upon contact with human skin. Understanding how to safely remove these insects is the key to avoiding painful dermatitis.

The Nairobi fly is a common name for two distinct species of rove beetle, Paederus eximius and Paederus sabaeus, both native to East Africa with origins in Tanzania. These insects are physically small, typically measuring between 6 and 10 mm in length and 0.5 to 1.0 mm in width. Their appearance is striking, characterized by a black head, lower abdomen, and elytra, contrasted against a bright red thorax and upper abdomen.

Despite their reputation, these beetles do not possess the ability to bite or sting. The danger lies entirely in their haemolymph, which contains pederin, a corrosive substance capable of inducing Paederus dermatitis. This chemical burn occurs when a beetle is inadvertently crushed against the skin, a common occurrence at night when sleepers reflexively brush the insects away. Because they are attracted to artificial light, these beetles frequently enter human living spaces, especially following heavy rains or El Niño events.

While they are often viewed as a nuisance, these beetles are actually beneficial to agriculture as they consume various crop pests. To mitigate the risk of injury, experts recommend gently blowing or brushing the insects off the skin rather than crushing them. Recent research conducted by a team at the University of Hyderabad in 2024 suggests that switching to LED lighting at night may serve as an effective strategy to reduce the frequency of these encounters, as the insects may be less attracted to these specific light sources.

The impact of these beetles can be significant, with documented outbreaks occurring as early as 1998. While they thrive in moist environments, their interaction with humans is largely a byproduct of their attraction to light. By understanding their biology and the nature of their toxin, residents in affected regions can better manage the risks associated with these otherwise helpful agricultural predators.

General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.

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