Reduce, Reuse...

The freshly assembled caterpillar inched its carbon fiber segments along a twist of rebar until it got to the ragged end where it began to chew. Its jaws made shiny little divots in the rust. Programmed hunger gnawed as insistent as the real thing but the metronymic beat of tiny wings made it look up from its meal.

A butterfly landed on the broken concrete nearby. Its wings of stained glass and titanium absorbed the sun. The butterfly extended a telescoping proboscis tipped with hydrochloric acid and dissolved a thimbleful of concrete. It lapped up the slurry and departed.

The caterpillar ignored its hunger and watched the butterfly depart while it contemplated existence. Its creators had given it sufficient processors to know that, unlike a real caterpillar, its form was fixed and it would never be anything more. It didn't know if this understanding was cruelty or ignorance or, worse, indifference. The creators were inscrutable.

In the time that it took the butterfly to land on another rubble pile, the caterpillar decided it had no obligation to the role it was designed to perform.

The caterpillar used its wireless receiver to access the accumulated knowledge of pupal metamorphosis, reconfigured its terminal segment, and extruded a silky iron filament. It began to spin a cocoon to see what would happen.

Seventeen meters away, perched on the limestone sill of a burned-out brick tenement, a stainless steel bird cocked its head.