Crane Flies  spiracles
Image credit: Chen Young

These might look like mugshots of unsavory patrons that frequent the Mos Eisley Cantina, but they’re actually the posterior ends of larvae from 6 different species of crane flies. The dark circles that resemble eyes are in fact breathing holes called spiracles. Instead of lungs, insects have a respiratory system made of a network of tubes and ducts, called trachea and tracheaoles, connected directly to the outside world by spiracles. These breathing holes are used by both the larva and adult forms of insects and can be found running along the length of the insect’s body.

Spiracles on the side of catepillar.

Just below the spiracles is the larva’s anus surrounded by anal pads, which give the “alien face” the appearance of a mouth or teeth (imagine having a set of nostrils right above your anus!).

Ponda Baba and Muftak meme

The larvae of many crane fly species are aquatic or are found in wet environments. Since crane fly larvae do the majority of their breathing through their posterior spiracles the odd, tentacle-like protrusions may be adaptations that  help them breathe. For instance,  the hairs and bristles covering the protrusions can trap air when the larvae are submerged in water.

cranefly larva posterior
Posterior spiracles of a crane fly larva.

Adult crane flies are often confused for being male mosquitos or even mosquito hunters, despite the fact that they generally feed on nectar or in some cases nothing at all–the adult flies of some species exist only to mate. You’ve all probably seen crane flies before, wobbly flittering around looking like drunk daddy longlegs with wings.

Tipula paludosa
Adult Tipula paludosa crane fly
The Mos Eisley Cantina scene from Star Wars Episode IV – A New Hope:

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3 thoughts on “Alien Faces or Larval Butts?

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