Kate Umbers was hiking through Australia’s Snowy Mountains in the autumn of 2008, when she saw her first mountain katydid—a thumb-sized insect with the colour and texture of a dead leaf.
“I recognised it from the guide books and picked it up excitedly,” she says. “It immediately vomited and flashed its bright colours.”
Emphasis on bright. The insect’s dull brown wing casings flew apart to reveal vivid bands of red, black, and electric blue.
The inconspicuous leaf suddenly transformed into a garish Christmas bauble.
Many animals do something similar. When a threat gets close, they flash bright colours, show off distracting eyespots, strike aggressive poses, and spray off-putting chemicals.
They hiss, rattle, puff, and arch. These spectacles are called deimatic displays and they are supposedly meant to distract or intimate predators. Bright colours, in particular, are often messages that scream:
“I AM TOXIC; DO NOT EAT ME.” For some animals, these claims are bluffs. For the mountain katydid, they are genuine warnings—this insect is full of foul-tasting chemicals.
But Umbers noticed something unusual about its displays: the katydid only flashed its colours after an attack.
“I was struck by how easy it was to catch them and how little resistance they put up,” she says.
“They waited until they had been grabbed before revealing any defences.”
Seventy years passed before Leichhardt’s grasshopper was officially ‘rediscovered’ in 1971 by Principal Research Scientist of CSIRO’s Division of Wildlife Research, J. H. Calaby. Calaby had returned to South Alligator River, now protected within Kakadu National Park, to spot a single male nymph on a sandstone pediment.
While Calaby’s find meant that the species was not extinct after all, it remains particularly rare and little studied, with just a few fragile populations sustained by three native species of flowering shrub within the Kakadu and Keep River National Parks.
Bright colouring in insects usually signifies some level of toxicity, as does this species’ tendency to spew a brownish liquid when agitated, but chemical analysis has turned up little evidence that these grasshoppers are harbouring any toxic compounds.
And weirdly enough, the species has no known vertebrate predators, which suggests that rather than being toxic, the brownish spew’s purpose is simply to taste awful. Classic spew.
In 1996, chemists William Kitching and Mary Fletcher from the University of Queensland analysed the species’ host plants to find certain compounds that are associated with bitter-tasting glycoside sugar groups, so they suggested that by feeding on these plants exclusively, the species cements its reputation as a terrible meal.
EUROPEAN BEEWOLVES: wasps that preys on bees, harbor symbiotic Streptomyces bacteria in specialized antennal reservoirs.
The bacteria are secreted into the wasps’ lair, later taken up by the wasp larva and applied to the larval cocoon where they produce antibiotics to protect the wasp offspring against pathogenic fungi.
Beneficial partnerships between microbes and animals like the European beewolf have inspired a rich body of research into the bioactive products of host-microbe interactions, which could have purpose in medicine and disease prevention.
CREDIT: Sabrina Koehler, Postdoc, Department of Medical Microbiology and Immunology