They stopped and unloaded their packs in a serene place where the creek flowed under an old fallen log that was velvety green with moss. All the surrounding trees were filled with hanging clusters of butterflies. Lone individuals dropped from the trees steadily like insect rain, trembling where they landed and taking their time to die. She wondered if this was a butterfly funeral, but you’d not know it from this science crew. They seemed in a fine mood, just getting down to business with their tape measures, plastic sheeting, boxes of waxed-paper envelopes, and smaller instruments she couldn’t name. Scales, things for taking measurements. Ovid Byron was a man possessed with purpose, setting his sights on the trees and immediately tramping off into the woods with Pete, pointing and talking as they mounted the incline.

Bonnie and Mako worked together to pull an extremely long nylon tape measure across the forest floor in a white line that followed the curve of the hill, crossing the full length of the area where butterflies filled the trees. Then they painstakingly laid out squares on one side of the tape measure or the other, at regular intervals, for unknown purposes. Their chat when she overheard it was more personal than scientific. They discussed music they’d put on their iPods, names she didn’t know, and shared complaints about the place where they ate breakfast, which they called “vile,” with its sluggish waitresses and country music. She wondered if it was any different from the Feathertown Diner, where she’d had to wear a tacky polyester apron and the boom box in the kitchen played George Strait and Patty Loveless from opening to closing. What a bewildering verdict: vile. Maybe they only meant it at half-strength, in the same way they used “epic” and “heinous” and “stellar.” They’d found a Mexican restaurant over in Cleary, deemed “righteous,” which was all news to Dellarobia. She sat on the mossy log feeling like a third wheel. These students had all been to Mexico, she’d learned, on a monarch project with Dr. Byron. No older than twenty-five or so, and already Bonnie and Mako had ridden airplanes, moved among foreigners, walked on the ground of other countries. Dellarobia had been nowhere. Virginia Beach, back when her father was alive and had relatives there, but that was it. She couldn’t even muster the strength for jealousy, given the size it would have to take. She had no hope even of visiting the Mexican restaurant in Cleary, righteous or not. Cub wanted nothing to do with foreign food.

She wondered if they knew about the landslide, where Josefina’s family had lived. That family had come back to see the butterflies, and sat in her kitchen getting acquainted afterward, a fact she’d withheld from Cub. Lupe and Reynaldo. It was a little awkward, but they were so eager to talk about the butterflies, and knew a lot of facts. That was touching. Lupe did speak some English, once she warmed up. They had two boys, both younger than Josefina, who sat on the floor with Cordelia in awe of her toys. Lupe told Dellarobia she was trying to find work cleaning houses or babysitting, and offered to look after Preston and Cordie if the occasion arose. Dellarobia had laughed, the poor leading the poor. It was a tempting offer, she said, if only she had someplace else to go.

Bonnie startled her out of her funk, calling out, “Hey, can we put you to work?” Dellarobia jumped to attention, reminding herself of Preston. While Mako did something with a handheld GPS, Bonnie gave her a small notebook and explained they were going to spend several hours on their knees counting the insects on the ground. The line made by the tape measure she called a transect, and the plan was to count every butterfly inside the squares they’d laid out along its length, which were called quadrats. They would keep track of the numbers in each square, and the sex ratio, which meant how many males and females. Bonnie asked Dellarobia to identify several butterflies by sex, to be sure she could do it, and Dellarobia was nervous but took her time and made one hundred percent. Her first test in a decade, aced. Bonnie tied yellow flagging along the transect, numbering the squares and assigning ten of them to Dellarobia. Mako and Bonnie would each take twenty.

Many questions occurred to Dellarobia, starting and ending with: Why in the world? If she told her family these people counted dead insects all day, they truly would not believe her. She wondered, were they looking at some kind of a disaster here? These might be dumb questions. All their efforts seemed bent on the simplest of measurements. She kept quiet, watching to see how they went about the task: kneeling, inching forward, noting numbers in two columns for male and female. She also noticed that if one fell from the trees onto their already-counted areas, they did not go back and pick up the tally. She surveyed her assigned corpses in despair, doubting she could count that high without just a wee little hit of nicotine. But she soon grew absorbed, feeling something change in her brain as her eyes shut out everything else in the world but the particulars of monarch butterfly color and gender. And noticing the smell: like dirt and lightning bugs, as Preston had said, and also like the firs themselves, musky-pungent. She hardly paid attention to odors, but this one grew on her. She was ready to agree with her son, the scent was good, at least here in its own world. Like dead lightning bugs in a jar, but not nearly that acrid. It was softer, more like rich black soil. Maybe it was the effect of all these deaths. Her lifetime-first miracle was becoming a force of decomposition.

She noticed that Mako and Bonnie took breaks from time to time, sitting back on their heels, closing their eyes or looking up into the trees. Several times he brought dead butterflies over to Bonnie and she measured them with a small silver instrument she kept in her pocket. They also had a hanging scale, a miniature version of a produce scale in the grocery, from which they dangled stacks of butterflies in waxed-paper envelopes. Dellarobia watched their faces as they read the scales and wrote down numbers in a speckled notebook, and felt deeply envious of their absorption in this work, the things they knew. Earlier she’d thought Bonnie and Pete must be a couple, because of the way he gave Bonnie a hand up across the creek, and she later brushed some dirt off the seat of his pants, and even pulled a plastic bag out of Pete’s front jeans pocket for him when his hands were full, a gesture that seemed intimate to Dellarobia. But now she observed the same nonchalant physical comfort between Bonnie and Mako when they stood close together, arms touching, while examining something. They reminded her of Preston and his friends absorbed in a game, boys and girls together, their differences undetected or overlooked. Dellarobia wondered how that would feel in adulthood, to be freed from the flirtations and oppressive rules of sex, a dread and thrill she could never seem to escape. Just sometimes, to be with men without being with them.