The Spotted Predatory Katydid
Hmmm, cute and spotty, l thought. I wonder what its name is, and if it is famous for anything?
Well, yes. This is the Spotted Predatory Katydid and if you’re a cicada, this is the last thing you’ll see before half of your head is ripped off (truly, only half).
The Predatory Katydid mimics the sounds and movements of a female cicada calling for a mate. The boys are lured in by the siren song of “click, click, click” and some synchronised dancing. When the cicada is close enough, the Katydid grabs it and subdues it (that’s the half-head eating thing). Then at leisure, the Katydid eats the rest of the cicada, all except the wings.
When this behaviour was discovered in 2009 it was the first example of an “acoustic aggressive mimic”.
The Monarch Butterfly (Danaus plexippus) using warning colors to show off that it tastes foul. It has some tasty Bayesian Mimics. The butterfly is not native to Australia but is fairly common.
A mimic is a creature which appears like another creature, so it can deceive the observer. I remember learning about mimicry at uni. Okay, I remember the concept; the details I had to Google. Generally, it’s “defensive mimicry”, like camouflage, and is used to hide from predators. An example is a caterpillar which looks and moves like a leaf blowing in the wind.
Another anti-predator option is use of warning colors: vivid black, white, red and yellow which advertise that you are a dangerous creature, or perhaps disgusting to eat. The mimics exploit this coloring: Mullerian mimics are different species that look the same and are equally dangerous, kind of like members of a bikie gang. Then there’s Bayesian mimics, or the copy-cats. These guys look like something nasty, but actually they’re weak and pretty tasty. There are some harmless butterflies that mimic the foul-tasting Monarch.
A Horsfield’s Bronze Cuckoo. So innocent-looking, but its nestlings are an aggressive mimic.
The “aggressive mimic” is a creature that disguises itself to look like another so it can be a more effective killer. It’s not as common as the “defensive mimic” but Horsfield’s Bronze-Cuckoo is an example. The Cuckoo lays its eggs in the nests of other birds. When the cuckoo nestlings hatch, they kick out the original babies, killing them. Then they mimic them, looking and sounding like them so the parent birds continue to look after them. Pretty evil.
Aggressive mimicry is also found in a few “sit and wait” predators who use behaviour, looks or smells to lure their prey within striking distance. The lures are general sexual, apparently that when creatures are at their dumbest. There’s a spider that emits a scent matching the sex pheromones of their moth prey. That is both evil and sneaky. The Predatory Spotted Katydid is the only creature known to mimic the sounds of its prey so it can eat them.
The Predatory Spotted Katydid (Chlorobalius leucoviridis) are distributed across arid, inland areas of Australia. They’re nocturnal and are often found high in a bush. It’s not fussy, it also eats flies, grasshoppers … and other katydids.
First published 17 March 2020
References
The original discovery “Versatile aggressive mimicry of cicadas by an Australian predatory katydid” https://pubmed.ncbi.nlm.nih.gov/19142230/
Detailed 2020 paper on “Camouflage in predators“ https://onlinelibrary.wiley.com/doi/full/10.1111/brv.12612 and an easier read https://www.wikiwand.com/simple/Mimicry
Beautifully written summary of the Katydid https://indianapublicmedia.org/amomentofscience/siren-song-spotted-katydid.php