Teleopsis, a fly with the eyes of a stalker

The story of a fly with several millimeter between its eyes.


Picture yourself by a stream, in a tropical forest of Indonesia.

[Southeast Asian jungle noise fade in]

You are resting on a leaf, safely encased and protected by the hardened skin you wore as a larva, your puparium. But as your development comes to an end, you are ready to emerge, and earn your name. You are a stalk-eyed fly, and you are about to grow your stalks.

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Let’s get back to your tropical riverside. After a larval life spent eating freshly rotting plant matter, you settled and started your metamorphosis into an adult fly. But you are not any fly, you are a Teleopsis dalmanni, from family Diopsidae, a Stalk-eyed fly. This implies that during the development of your new head, your eyes found themselves at the end of elongated stalks, linked to your brain by elongated optic nerves. When you will be finished getting out of your protective puparium, the moment will have come to expand them and gain all the eye span you can. There’s really no option to do it later, when your exoskeleton will be hardened. It’s now or never!

You start pumping air bubbles in your stalks, making them align perpendicular to your body axis and going on both sides of your head. If they are long enough, you will be a very seductive fly. Even if they don’t really do anything useful, they are still used by female of your species to judge how good of a mate you can be. You will face other males, and compare your eye span to theirs.

You are like a miniature stag, or even a miniature stag beetle because you’re really small. Bound to develop cumbersome organs, just to show you can spare so much resources into useless sexiness.


Buschbeck, E.K., Roosevelt, J.L. and Hoy, R.R. (2001) ‘Eye stalks or no eye stalks: A structural comparison of pupal development in the stalk‐eyed fly cyrtodiopsis and in drosophila’, Journal of Comparative Neurology, 433(4), pp. 486–498. Available at:

Rogers, D.W. et al. (2008) ‘Male sexual ornament size is positively associated with reproductive morphology and enhanced fertility in the stalk-eyed fly Teleopsis dalmanni’, BMC Evolutionary Biology, 8(1), p. 236. Available at: