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Claim check

Does a fungus turn cicadas into zombies?

Exaggerated

Something true sits underneath, stretched well past what was shown.

The abdomen really is replaced by a plug of spores while the animal flies around, and infected males really do give the female mating signal. What has never been shown is that the fungus controls anything, or that the detected drugs do anything.

The claim as it circulates

“A fungus drugs cicadas with amphetamines and psilocybin, replaces their abdomen, and takes control of their behaviour to spread itself.”

Where you may have met it: Coverage of the 2019 Massospora alkaloid paper, which was extensive; Comparison with the ant-controlling Ophiocordyceps, which is a different fungus with a different evidence base; Horror and "nature is metal" content

Taking it apart

What was claimed
That Massospora chemically drugs cicadas and takes control of their behaviour, making them into zombies that spread its spores.
What was actually observed
Massospora infection destroys and replaces the posterior abdomen — genitalia included — with a chalky spore mass, while the cicada continues to fly, walk and attempt to mate. Infected males were observed producing the female-typical timed wing-flick response to other males' calls in addition to calling themselves, and healthy males approached and attempted to mate with them, transferring spores. Chemical analysis detected cathinone, an amphetamine, in cicadas infected with one Massospora species, and psilocybin in another.
What the evidence supports
That the physical destruction and continued activity are real; that infected males produce a signal that draws in other males, giving the fungus access to both sexes; and that two unexpected psychoactive compounds are detectable in infected animals.
What it does not support
Any causal link between the compounds and the behaviour. No study has established the concentration reaching cicada tissue, any dose–response relationship, or any effect of these compounds on insect behaviour — and insect nervous systems differ from vertebrate ones in the relevant receptors. Nothing shows the fungus acting on the nervous system at all. The behavioural change may equally result from the extensive physical destruction of the signalling apparatus; no study distinguishes the two.

Several separate facts get welded into one sentence here, and only some of them are established. Taking them apart is most of the work.

Established: the abdomen is gone, replaced by spores, and the animal carries on. Established: infected males give the female signal, drawing in healthy males who try to mate with them. Established: an amphetamine turns up in one species and psilocybin in another, which is chemically remarkable given that the fungus is unrelated to anything that normally makes either.

Not established: any connection between those last two. Nobody has measured how much of either compound reaches the cicada's tissues, whether that is enough to affect anything, or whether these compounds affect insect behaviour at all. "Mind control" names a mechanism for which there is no evidence — and the comparison people reach for, the ant-controlling Ophiocordyceps, has decades of work behind its mechanism that this simply does not.

The observation is extraordinary without any of that. A fungus that eats a third of an insect, leaves the rest flying, and gets spread by the animal's continued attempts to mate does not need to be a mind-control story to be worth telling.

The claims underneath

Each one carries its own evidence, scope and caveats. Expand any of them to reach the studies.

The fungus really does replace the abdomen and change the signalling — how is unknown

Contested

Researchers actively disagree, and the disagreement is substantive.

Massospora infection of periodical cicadas replaces the posterior abdomen with a mass of fungal spores while the animal remains active. Infected males have been observed producing the female-typical timed wing-flick response to the calls of other males, in addition to calling; healthy males approach and attempt to mate with them, transferring spores. Infected animals of both sexes continue attempting to mate despite the loss of the genitalia. Cathinone has been detected in cicadas infected with Massospora cicadina and psilocybin in a different Massospora species. No study has established that these compounds cause the behavioural changes, at what concentration they reach cicada tissue, or that the fungus acts on the nervous system.

Who this applies to
Massospora infections of periodical and some annual cicadas
Studied in
Massospora cicadina, Magicicada, Massospora platypediae

You may have heard

“A fungus drugs cicadas and turns them into zombies under its control”

Several separate things get welded into one sentence, and only some are established. The abdomen really is replaced by a plug of spores while the animal flies around, which is stranger than the framing. Infected males really do give the female signal, drawing in other males and spreading spores to both sexes. An amphetamine really was detected in one species and psilocybin in another. What has never been shown is any link between those last two facts: no concentration at a site of action, no dose–response, no demonstrated effect on insect behaviour, nothing indicating the fungus acts on the nervous system. "Mind control" names a mechanism nobody has evidence for.

Why we rate it this way, and what the caveats are
ContestedModerate confidence

The physical replacement of the abdomen and the continued mating behaviour are directly and unambiguously observed. Whether the fungus manipulates behaviour, and by what means, is unresolved: the alkaloid finding is suggestive and every causal step between detection and behaviour is missing.

Where researchers disagree

  • The behavioural change may be adaptive manipulation by the fungus, or a by-product of extensive physical destruction of the abdomen and its associated signalling apparatus. No study distinguishes these.
  • The alkaloids were detected but their concentration at any site of action is unknown, no dose–response relationship has been established, and insect nervous systems differ from vertebrate ones in the receptors these compounds are known to act on.
  • The biosynthetic route in Massospora was not identified, so whether the fungus makes these compounds or acquires them is unresolved.

Still unanswered

  • Does Massospora act on the cicada nervous system at all, or is the behavioural change a consequence of tissue destruction?
  • Do the detected alkaloids reach concentrations at which they affect insect behaviour?

Last reviewed 2026-08-11

The evidence (2 studies)

Go deeper

Periodical cicadas

Seventeen years underground, then a few weeks above it, and the whole defence is being too numerous to eat.

Last reviewed 2026-08-11