South of Fall Creek by the edge of the woods, the moths would gather.
They were, of course, drawn by light — set out by a researcher working in Cornell University’s old Insectory building. In 1889, the lure came from a kerosene lantern, the pan underneath collecting the samples. In 1919, a researcher set up another light trap, baited by the orangish glow of an early tungsten bulb.
A team of biologists used datasets both old and new to discover how flight periods of moths in Ithaca, N.Y., have changed over the past century. “Phenological shifts and increases in voltinism within a moth community over a century of anthropogenic change” appeared recently in the journal Ecology; its first author is former Binghamton University undergraduate Emma Foster ’24. Foster is now pursuing a doctorate in plant evolutionary genetics at the University of Michigan; the project began as her undergraduate honors thesis in biological sciences.
“Our overall finding is that moths are flying on average about two and a quarter weeks later in the year,” said Assistant Professor of Biological Sciences Eliza Grames, a co-author on the study.
The likely reason additional generations of moths, potentially taking advantage of the warmer summers and longer growing conditions for their host plants.
Missing species
The old datasets — from 1889 to 1892 and 1919 to 1922, respectively — came to light by sheer chance. A Swiss filmmaker discovered insect monitoring datasets from old agricultural research stations, including Cornell; an email chain on this discovery eventually ended up in Grames’ inbox.
That led to a visit to Cornell’s Insect Collection, where an old cabinet in the corner contains notebooks of experiments — and the specimens in the collections themselves, pinned with outstretched wings.
The researchers cross-checked the experiment location with old campus maps and found that both the 1890s and 1920s datasets were conducted within meters of each other, outside the old Insectory building. The dataset from the 1890s contained 52 species, while the one from the 1920s featured 347. Some species appeared in both datasets, while other species were reclassified in the years since; there were also species that couldn’t be identified without dissection.
Entomologists typically pin and preserve specimens, which enables them to extract DNA or perform dissections in the future, Grames said. In Cornell’s collection, Foster found a moth that a scientist collected in 1919, one of the actual data points recorded in the historical dataset.
For more recent data, the team used the citizen-science app iNaturalist to track the species and location of moths in the Ithaca area today, as well as data supplied by study co-author Jason Dombroskie from Cornell University, who has run light traps in his backyard for years. Ultimately, they looked at 78 species across the datasets, marking changes in their flight times over the past century.
The researchers also discovered something else: 13 missing moth species that were observed in Ithaca historically but have not been seen in over a decade. One, a devastating cotton pest, was deliberately eradicated from North America; most of the others are now found at higher elevations or farther north — potentially a signal of climate change.
“It doesn’t mean they’re not there; it could be that they are really rare,” Grames said of the lost species.
Lost species like the 13 missing from the Ithaca area may not actually be locally extinct, and efforts to document the loss of species could prompt rediscovery, she said.
The hunt for data
As part of the project, Foster digitized hand-drawn bar-plots from the historical phenology records, making them available for future scientists. More discoveries may await: that Cornell cabinet contained other datasets that haven’t yet been digitized, Grames noted.
Data gathered by long-ago naturalists may prove a treasure trove to scientists tracking large-scale changes in the environment. But finding that data can be a bit like an actual treasure hunt.
By way of example: The Cornell cabinet led to a Horseheads High School math teacher who jotted down his 1930s insect data in notebooks, a fact mentioned in his obituary. His notebooks, sadly, weren’t at Cornell.
“We know where his favorite sampling locations are, but we have no clue where his notebooks are,” Grames said. “I want to track them down because they could help us understand more what happened over the past century.”
Clues led to his last surviving relative: a sister, who served as the town historian in Sardinia, N.Y. There, the trail stops: The sister died in the early 2000s. The family home sat empty for a decade and was ultimately demolished in 2016.
“There’s potentially a ton of other datasets we just don’t know about that are potentially valuable,” Grames said. “I wish more people would digitize them or at least make them known: If someone told me ‘My grandpa had this notebook and he detailed every single butterfly in the yard for 20 years.’ I’d love that and it would be really valuable for insect conservation.”