One late July afternoon during Hester’s first year helping out, Henrietta led her into the vegetable patch behind the house where their mother had once taught them to pick hornworms off the tomato leaves and toss them into the chicken coop. Now they gathered a dozen smaller hornworms, about an inch long: through their third molt, Henrietta explained, but not yet their fourth, so the young lepidopterists would still have plenty to see. She’d been telling them how an adult might lay eggs, a larva be induced to pupate; how a chrysalis, treated kindly, might in some months open to reveal a moth who might lay eggs. They might work out a creature’s life history by starting anywhere.

Six little tin boxes for her six students; two caterpillars and a handful of fresh tomato leaves in each box: Hester helped with that. A few days later, the youngsters watched their caterpillars squirm and flex until the old skin burst behind the head and the face covering, pushed forward by the new, larger head, hung like a horse’s feed bag. As the new caterpillars crawled from their old skins, the youngsters noted the date and the time each broke free. Length 2 inches, Eleanor wrote. Pale-green head with white dots. Buff spiracles circled with black; long sharp horn in back; body bright green with yellow V-shaped markings. Very hungry!

Mandy, shielding her neck as if the caterpillar might leap up and bite her, said uneasily that they ate as if they’d never stop. The leaves in the boxes melted away, transformed into green flesh. Soon the caterpillars were as long and thick as Henrietta’s own substantial forefingers, and so strong that when Amy forgot to put the square of scrim Hester had given her over the tin box and under the lid, her caterpillars stood up on their hind prolegs and—were they squeaking?—pushed the lid off the box.

Thomasina quit the club after those heavy green heads poked out, but the others stalwartly added dirt to their boxes and watched the caterpillars burrow into it to emerge, two weeks later, as pulpy green pupae that hardened over a few hours into shapes they’d seen in their own gardens but not always recognized. Orestes marveled at the way the tube of the tongue case moved blindly through the air until the tip touched the wing covers and the whole structure solidified into a firm brown object, as shiny as a chestnut, with handsome curved segments and the tube containing the tongue arched back like the handle of a jug.