The Energizer bunnies of evolution

Originally published 26 July 1993

Any­one who has watched a drag­on­fly scout a sum­mer pond has seen one of the won­ders of evolution.

A cross between a traf­fic-watch chop­per and an F‑16. A flaw­less match of form and func­tion. A fly­ing machine opti­mized for snap­ping up insects on the wing.

And for sex. But more of that in a minute.

Every now and then evo­lu­tion throws up a crea­ture so per­fect­ly adapt­ed to its way of life that improve­ment seems impos­si­ble. Such species are reward­ed by longevi­ty. They sur­vive for eons with lit­tle change. They become what evo­lu­tion­ary biol­o­gists call “liv­ing fossils.”

The drag­on­fly is a liv­ing fos­sil, one of the old­est orders in the ani­mal kingdom.

One famous drag­on­fly fos­sil from the Juras­sic lime­stone of Ger­many is 200 mil­lion years old. Every wing vein is record­ed with aston­ish­ing fideli­ty. The pat­tern match­es in almost every detail the draw­ing of a drag­on­fly wing in my Peter­son Field Guide to the Insects. The fos­sil insect seems ready to take flight, released from a 200-mil­lion-year sleep to join its mod­ern cousins.

Drag­on­fly fos­sils have been found in rocks as old as the Car­bonif­er­ous Era of Earth his­to­ry, 300 mil­lion years ago. Some of these ancient fly­ers had wingspans greater than two feet. Dinosaurs came and went, ptero­dactyls flour­ished and dis­ap­peared, thou­sands of species of mam­mals evolved and became extinct: Drag­on­flies go on and on, the Ener­giz­er bun­nies of evolution.

Sit by the sum­mer pond and watch them. You might as well be in a time warp. Glance up and see Tricer­atops graz­ing near­by. Or thun­der­ing Tyran­nosaurus rex. Aster­oids smash into the earth and rep­til­ian giants become extinct; the drag­on­fly survives.

Ento­mol­o­gists sep­a­rate the order Odona­ta into drag­on­flies and the more del­i­cate dam­selflies, but for most sum­mer pond watch­ers, and in pop­u­lar par­lance, they are all the same.

Iri­des­cent eyes, tens of thou­sands of glit­ter­ing facets. Shim­ming blues and greens. Opal. Blood red. Ultra­ma­rine. No won­der drag­on­flies are tal­is­mans of sum­mer, one of the few insects we wel­come to the sea­son of exposed skin.

Grey­backs, club­tails, darn­ers, bid­dies, and skim­mers. Their names evoke poet­ry. Pop­u­lar names are even more evoca­tive. Water maid­ens. Demoi­selles. Horse stingers. Mos­qui­to hawks. Dev­il’s darn­ing nee­dles. Snake doctors.

When I was a kid, I was told drag­on­flies stitch up the eyes of sleep­ing chil­dren. They are also sup­posed to min­is­ter to injured snakes, sewing up wounds and nurs­ing them back to health.

But it is the fly­ing that makes it pos­si­ble to sit for hours beside the pond or stream, watch­ing them move. Drag­on­flies may be the most ele­gant fly­ers on the plan­et. For­wards, back­wards, straight up or down. Zip. Spin. Stop on a dime. The cen­ter of grav­i­ty lies just below the base of the wings, with heli­copter bal­ance. Oppo­site wings are con­nect­ed by strong flight mus­cles, and the two pairs of wings oper­ate inde­pen­dent­ly. A big drag­on­fly can reach an air speed of 60 miles per hour.

Pure fly­ing machine. The drag­on­fly­’s legs are not made for walk­ing, but for clutch­ing a reed or twig when it comes to rest. Or for scoop­ing up fly­ing insects. The drag­on­fly uses its net­ted legs like a shop­ping cart. It has been known to gath­er up 100 mos­qui­toes at a time.

I have a spe­cial place for watch­ing aquat­ic insects, a plank bridge across a slug­gish stream on con­ser­va­tion land. Lay prone and your face is a foot from the sur­face of the water. Water strid­ers and whirligigs in the late spring. Back­swim­mers in the fall. And drag­on­flies in summer.

The males take up ter­ri­to­ries near the banks of the stream. Perch­ing on reeds or stones. Chas­ing off intrud­ing males. Patrolling. It’s a dom­i­nance sort of thing. Estab­lish­ing pri­or­i­ty. The male in charge get the chance to mate.

But there’s a bit a busi­ness to take care of first. The male’s gen­i­tal open­ing is near the tip of his tail. The penis, how­ev­er, is just behind the legs. So before he mates, the male must trans­fer sperm from the tip of the tail to the penis up front.

Now he grasps the female behind her head with the tip of his tail. She curls her abdomen around and under until she brings her gen­i­tal organ — at the tip of her tail — to his penis. Now their bod­ies are engaged in a heart-shaped valen­tine, one of nature’s more engag­ing­ly semi­otic acts of cop­u­la­tion. Some­times they stay in this posi­tion for a per­plex­ing­ly long time, per­haps to ensure fer­til­iza­tion, or maybe because they are too love-besot­ted to let go.

Many drag­on­fly pairs do not dis­en­gage even when they dis­en­tan­gle their valen­tines. They dart about in tan­dem, the male still grasp­ing the female’s neck while she lays the eggs. Every pond-watch­er has seen these linked pairs, as adept at dou­bled post-coital flight as when solitary.

Evo­lu­tion­ists tell us that sil­ver­fish are the most ancient insects that sur­vive more or less unchanged into the present. Cock­roach­es and drag­on­flies are almost as old. Of these liv­ing fos­sils only the drag­on­fly is an unmit­i­gat­ed boon to humans. An iri­des­cent exter­mi­na­tor. A 300-mil­lion-year-old beau­ty on the wing.