Question of the month

From drab to fab

A pyrgomorph grasshopper, showing off its tiny red wings. Photo courtesy of Greg Dyer.

We’ve recently received multiple questions about insects caught in the act of flashing colourful body parts. What are they, and what are they doing?


Answer

The bizarre Dead-leaf Mantid of Borneo flashes its dark hindwings. Photo courtesy of Steve Wilson.

Every animal faces the threat of predation, and must employ some means of defence. Numerous defensive techniques have evolved; some animals are active at times when their predators are not, others carry heavy armour, or produce powerful toxins or foul-tasting chemicals. Many insects rely on camouflage, hiding from keen-eyed predators such as birds. However, stealth is not always sufficient, and a second line of defence is sometimes needed. When imminent danger threatens, many insects suddenly switch from stealth to showing off! This type of defence is called a ‘threat display’, and can act as a warning to predators that their intended prey is armed with distasteful or toxic chemicals. Alternatively, the display may be bluff, or merely intended to startle the predator away.

The insect in the photo at top is a species of Monistria, commonly called Pyrgomorph Grasshoppers. Pyrgomorphs are fairly sluggish grasshoppers, preferring to walk rather than hop. If they feel threatened they will flash their small but very colourful wings (the red wings visible in the photo).

The video below shows a female Mountain Katydid (Acripeza reticulata), flaunting its colourful abdomen (Video courtesy of Jiaorong Li). Most of the time the red and blue stripes on the abdomen are hidden beneath the katydids’ wings, making the insect hard to spot on the forest floor.

Among insects, threat displays are also employed by some phasmids (Stick Insects), mantids (Praying Mantises), and lepidopterans (moths and butterflies). Many other groups of animals also use threat displays; for example, Frillneck Lizards and Bluetongue Skinks both take their names from their distinctive threat displays.

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