Behind her, Hester circled the worktable, offering each youngster two pieces of white notepaper before taking two for herself and settling down on the remaining stool. Henrietta followed with a tray of spread and pinned mourning cloaks. “They’re so dark,” she continued, laying one deep purplish-brown specimen at each place, “that it’s even harder than usual to see the veins in the wings. We’re going to remove the scales so we can see the venation clearly.”

The air coming in through the partly opened windows was fresh and cool, smelling of earth and the granular snow still mounded in dark corners and against the walls. A cardinal was singing, some tufted titmice as well, as she showed Hester and the youngsters how to breathe on the top sheet of paper, lay it down over the butterfly wing on the bottom sheet, and then rub the top sheet gently with their fingernails. In that moment Henrietta was so happy she might have turned into a hummingbird moth herself.

“Lift the top papers gently,” she said. “Now let those scales fall into the little glass dish next to you, breathe on the paper again, and repeat.” Jennie smiled as the whole top wing became transparent, the veins standing out strongly. Henrietta pointed out the costal and subcostal veins, the multiple branches of the medial veins. Hester, who had done this exercise the previous spring, said from her end of the table, “I’m always amazed when this works.” The youngsters drew diagrams as Henrietta passed out hand lenses and talked about the strength of the skeletons they’d uncovered.

After she had them look at some of the scales, she and Hester cleared everything away and then she brought out a little bottle of benzine, a paintbrush, and the last pinned specimen. “Here’s something else we can do,” she said. “When we have a rare specimen we don’t want to destroy, we can still get a quick look at the veins without scraping the scales off.”

She moistened a rag with the benzine and gently dabbed it over the wings. The color faded and then disappeared, leaving only the veins behind, their structure so clearly marked there might have been no scales at all. “Look quickly,” she said, holding out her own hand lens. “It doesn’t last.”

She looked up as Hester made a noise and winced at the smell of the fumes. A few seconds later Hester backed away from the table with both hands pressed to her mouth, stepped outside, and bent over the window box.