A mantis showing “special resemblance”

April 13, 2017 • 10:00 am

by Greg Mayer

We’ve often highlighted here at WEIT the remarkable phenomena associated with mimicry, the often marvelously detailed resemblance of organic beings to other organic or inorganic features of their environment. On a trip to Costa Rica in January, while out for a nightwalk at La Selva Biological Station with Jon Losos, we came across a hooded mantis, probably in the genus Choeradodis, on a broad leaf. Many kinds of insects resemble leaves, having what Hugh Cott called a “special resemblance to particular objects”. The thorax is broad, flat, and the same color as the leaf, while the folded wings are leaf-shaped and have what looks like venation. The opened wings can also look leaf-like (browse the images here). There are even some mantises which mimic dead leaves. What struck me about this mantis, though, was that the insect also had a blemish on its thorax, looking very much like the blemishes on the leaves.

Choeradodis (a mantis), Estacion Biologica La Selva, Costa Rica, January 2017.

Can you tell which of the following is on the mantis, and which on the leaf? You probably can figure it out by using cues of lighting and haphazard details in this particular image, but not by any in principle distinctions.

What is remarkable about this is not just the resemblance, but the asymmetry of the blemish on the mantis, indicating that its position is unlikely to be a constant pattern feature. I do not know what causes the leaf blemishes– a fungus? insect damage? Could the blemish on the mantis also be an induced pattern element of some kind, but in this case one that enhances the mimetic resemblance, and breaks the symmetry of the insect?

I could not find any reference to asymmetric mimicry of blemishes in a quick perusal of classic references, or the internet. Are there any tropical biologists, entomologists, or plant pathologists out there who can perhaps enlighten us?

Cott, H.B. 1940. Adaptive Coloration in Animals. Methuen, London. [“reprinted with minor corrections 1957”]

Wickler, W. 1968. Mimicry in Plants and Animals. McGraw-Hill, New York.