Sunday 6 October 2013

Wings of a Feather

Image: George Poinar Jr. & John T. Huber
Disney's Dumbo was a silly, little elephant who thought he could fly by means of a single feather. It's an understandable delusion, given his situation. He was raised by a mouse in a circus after his mother was deemed clinically insane. From an early age he was ostracised by his own kind, bullied, abused and forced to work a humiliating job which he hated.

No wonder the wretched cherub wanted to fly away.

Except that he could fly away. But not because of the feather. It was much more to do with his gigantic pair of ears and a peculiar cessation of reality and physics. Because all things are possible when you have truly gigantic ears.

But there are creatures out there who really can fly using nothing but a couple of feathers. They don't require a cessation of reality and they don't even need ears of any size whatsoever...


Image: John T. Huber
The recently discovered and delightfully named Tinkerbella nana.
The scale bar is 100 μm long, the width of a human hair
Fairyflies are actually wasps. Tiny wasps. Teeny-weeny, itsy-bitsy, ickle-lickle wasps. They're the smallest of all adult insects. The smallest winged insect is a Fairyfly 155 micrometres long. The smallest wingless insect is a male Fairyfly who is 130 micrometres long.

There are one thousand micrometres (μm) in a single millimetre, so 155 μm is 0.155 mm or about one 160th of an inch. That's smaller than many amoebas!

I tried to find something of similar size...

Image source
And I found a single pixel on the Apple iPhone 3G display.

The world feels quite different at this scale - air is no longer the wispy void you cut through so effortlessly as gravity pulls you into the bright waters of a swimming pool when you won that gold medal for diving (congratulations!). Instead, it feels more like the water! Thick and exceedingly present. You don't fall, you sink. So when you're even smaller than a normal-small insect, these feathery wings are a great help in reducing turbulence and drag as you fly.

There are over 1,000 species of Fairyfly all over the world and they're so incredibly tiny that almost all of them are egg parasitoids. They lay their eggs inside the eggs of other insects! When the Fairyfly grub hatches, it eats the host egg and gets all the food it needs to pupate and emerge as an adult. That's the difference between parasitoids and parasites - parasitoids kill their host.

Tinkerbell's shocking secret revealed!

Image: Udo Schmidt
Oligella foveolata
It's 0.55 mm long!
Feather-winged Beetle
Do I need to tell you that Feather-winged Beetles are the tiniest of all beetles? The biggest of them are around 2 mm long, the smallest just 0.5 mm. That's 500 μm, so they still dwarf the smallest Fairyflies. They can only lay one remarkably large egg at a time. It's often about half the size of the female it came from, so even their eggs are bigger than the smallest Fairyflies. Bad news, given the parasitoid thing.

Hundreds of species have been described so far and there are lots more in museums all over the place, gathering dust as they await a scientist with a steady hand and a good microscope to give them a name.

Image: Natural History Museum of Denmark
Baranowskiella ehnstromi
Feather-winged Beetles live in the midst of rot and decay in leaf litter, logs, dung, sea weed and anywhere else they can find fungus to feed on. One species, Baranowskiella ehnstromi is the smallest beetle in Europe. It reaches 0.45 mm long and lives its entire life in the pores of one particular species of bracket fungus which grows almost exclusively on willow trees.

Image: W. Eugene Hall
It sounds like some Feather-winged Beetles don't actually use their feather-wings much!

Image: Alton N. Sparks, Jr., University of Georgia,
Thrips are an entire order of insects containing at least 5,000 species. Most of them are tiny, about 0.5 to 1 mm long, and feed on plants, fungal spores or pollen. Other Thrips are huge! 15 millimetres! 15! That's more than half of an ENTIRE inch! Needless to say, such goliaths are predators of insects and mites. No doubt they simply overpower them through the sheer physical force afforded by their colossal size.

Image: Smith609
Truly luxuriant wings!
Thrips are a bit like true bugs in some ways. They go through incomplete metamorphosis, which means their young look a lot like adults and don't have to go through pupation like maggots, grubs and caterpillars do.

Secondly, they have piercing mouthparts for sucking their food out of plants or prey. There's this one interesting difference, though. True bugs have a pair of long, thin mandibles that form a kind of straw for sucking up fluids. In Thrips, only the left mandible becomes the straw. The other one is tiny and useless or absent entirely.

Image: Jürgen Mangelsdorf
Alucita hexadactyla
Twenty-plumed Moth
And for a complete change we have the remarkable Twenty-plumed Moth! These little moths don't fly on one feather, nor 2 or even four. Instead, each wing is transformed into a whole bundle of feathers, creating an amazing fan of 20 in total.

It belongs to a whole family of about 130 similar moths called Alucitidae, the Many-plumed Moths. They're found in temperate and subtropical regions, and the Tweny-plumed Moth in particular comes from Europe and was introduced into North America.

These moths are small, but not unbelievably tiny. The Twenty-plumed Moth has a wingspan of around 15 mm, about as long as a gigantic Thrips. Unfortunately this is the perfect size for people to see it, but totally overlook it. A shame, since this is a "little brown moth" with a difference!

Image: Gyorgy Csoka, Hungary Forest Research Institute,
There's a caterpillar in there
The caterpillars are probably a lot more noticeable. They're still tiny of course, but they're leaf miners. They live inside a single leaf of a honeysuckle tree and tunnel through it using nothing but a mouth and an appetite. It's like a miner with a sweet tooth in Candyland. Or a vegetarian with a giant carrot. Something like that.

In any case, we can finally see where Dumbo got it so wrong. He was an order of magnitude out. Not 1 feather... 20! Someone needs to tell the pigs. All things are possible when the pigs fly.


TexWisGirl said...

some are quite dainty looking.

Joseph JG said...

Yes, they're quite pretty!

Lear's Fool said...

I'm still giggling at the 'Thripzilla' mental image.

Joseph JG said...

THRIPZILLA! I wish I'd thought of that. There was a book called Thripz where they run rampage and kill people:

I think we have the sequel!