The wings
A structure that begins compact around the body, opens to a much larger surface that can face the sun, and folds back again, every day, without fail. Insects have done this for 300 million years.
The requirement
Flowers that open and close, growth in plants, shells and bird wings were all considered. Bird wings led to insects, and insects turned out to be the richest source of all.
A small, aerodynamic state around or on top of the body.
Expand to a much larger surface that can be turned toward the sun.
Return to the compact state, repeatedly and reliably.
Five wing structures
Each insect was traced in plan view on a millimetre grid, folded and extended, and the areas compared. The multiple is extended area divided by folded area. The plates are shown as they were drawn.
WS1
Chortoicetes terminifera
The broad hindwing is pleated like a fan and stowed beneath a narrow, leathery forewing. In flight it opens radially from the wing base into a surface ten times its stowed footprint.
For design. Radial fan pleating from a single hinge gives the largest area gain of the five. Suited to large deployments when parked or moving slowly.
WS2
Coptotermes acinaciformis
Four long, flat wings lie stacked along the abdomen. They swing out from a single root on each side without any folding of the membrane.
For design. Stacked rigid blades rotating from a hinge point. The simplest mechanism and the lowest stowed profile.
WS3
Froggattoides typicus
Clear, stiff wings with strong veins rest in a tent over the body, forming a smooth roof. They rotate outward and forward into a wide flight surface.
For design. The resting wings are the body’s envelope. A tented canopy of framed panels can be both skin and collector, and the veins suggest a frame for thin cells.
WS4
Sarcorohdendorfia hardyi
The wings do not fold. They sweep back over the body at rest, with a total area only a little larger than the body.
For design. The baseline case: fixed surfaces with minimal mechanism. It sets the benchmark each folding structure has to beat.
WS5
Xylotrupes gideon
Hardened forewings form a shell. Beneath them the membranous hindwings are folded origami-fashion. In flight the shell lifts and the hindwings unfold to five times the covered area.
For design. A protective carapace over a folded collector: a hard body that shields a delicate surface when stowed.
The re-measure
Instead of museum specimens, the atlas measures the plates of R. J. Tillyard’s The Insects of Australia and New Zealand (1926), a public-domain textbook printed at natural size.
Each figure is scanned at 360 dpi, scaled, traced, and split into body (blue) and spread wing (red). The body is the smallest footprint the wings could be stowed within, so wing area over body area is the collecting area a design gains over its stowed plan. Three new types joined the original five: the vertical clap, the lengthwise pleat and the earwig fan.
| Type | Insects | How it stows | Area gained |
|---|---|---|---|
| WS1 Fan pleat under a cover | Grasshoppers, stick insects, mantids, stoneflies | A narrow, hardened forewing lies over a broad hindwing that closes along radial pleats like a hand fan. | 10.6× |
| WS2 Flat stack | Termites, sawflies, bees and wasps | No fold at all. The wings lie flat, one over the other, and swing out from a single root. | 2.0× |
| WS3 Tented roof | Cicadas, lacewings, caddisflies | Framed wings rest roof-wise over the body and form its outer envelope. They do not fold; they rotate out to fly. | 8.4× |
| WS4 Fixed span | Flies and dragonflies | The wings never fold. The baseline every folding type has to beat, and the most precisely controlled wing there is. | 1.5× |
| WS5 Shell over origami | Beetles and ladybirds | Hard wing cases lift, then a hindwing folded across its length springs open at its crease. | 5.0× |
| WS6 Vertical clap | Butterflies and damselflies | The wings close upright over the back, the smallest stowed footprint of all. | 8.6× |
| WS7 Lengthwise pleat | Paper wasps and potter wasps | Each forewing folds once along its length. A click at the base gives it two stable positions. | 2.2× |
| WS8 Earwig fan | Earwigs | A fan that spreads while its cross-creases snap flat. Bistable: it holds open and shut with no muscle at all. | 10× |
Medians of wing area over body area from the Tillyard plates, except WS5 (folded to open, from the 2003 rhinoceros beetle and published laboratory ratios) and WS8 (published ratios, as Tillyard draws earwigs with their wings closed).
What the numbers say
The fan pleat and the earwig fan give the largest gains, about ten times or more. The tented roof and vertical clap reach similar multiples but rest outside the body.
Only the fan pleat, the shell over origami and the earwig fan keep the collector under cover when stowed: what matters for anything that must survive hail, branches and dust.
The lengthwise pleat and the earwig fan hold open or shut without power, which removes a lock and the motor that drives it.
Living wings
Insect wings are not inert. Their veins carry blood, air tubes and nerves, and small hearts in the thorax draw the flow back.
So the atlas records veins as structure, plumbing and sensing at once. A solar surface turns most of the light that falls on it into heat; veins that carry coolant can move that heat away, as a dragonfly moves heat through its body with its heart.
The dragonfly
Every other insect here is a lesson in folding. The dragonfly is a lesson in flying, sensing and control.
A dragonfly wing looks flat but is folded in section. Main veins run in ridges and valleys, like corrugated iron, and cross-veins tie them into thousands of cells.
A flexible joint with a mechanical stop at the kink in the leading edge. It lets the outer wing twist for lift, and stops it twisting too far.
A small, heavy cell near each tip. It acts as a tuned mass that stops the wing fluttering itself apart, which suggests a weighted tip for any large wing held in wind.
Each of the dragonfly’s four wings has its own muscles. Changing the timing between the pairs lets it hover, fly backward and sideways, glide, and catch other insects in the air up to 95% of the time.
Its brain is the model for the controller a self-energising product will need: sensing, attention, prediction and reflexes, running the wings and the energy together.