They arrive in wooden drawers with glass tops and in glassine envelopes - sometimes by the truckload. Last year, 333,000 butterfly and moth specimens were sent to the Florida Museum of Natural History in Gainesville.
But where once the delicate specimens were catalogued and, sometimes, displayed, they're now playing a new role: nature's telltale.
Butterflies are good environmental indicators, biologists say. Tracking the types and numbers of butterfly species across time and space can provide early warnings when something is amiss. That's why Jacqueline Miller, cocurator of the museum's McGuire Center for Lepidoptera and Biodiversity, is using its more than 3.5 million specimens to create a detailed national butterfly database.
If it succeeds, the United States will have in place a biological gauge to measure everything from the health of prairies to changing weather patterns. It will also be following in the footsteps of Canada and Mexico, which already have butterfly databases.
"People think these are dusty old things," Dr. Miller says. "But there is a lot of information locked in these collections."
For example, many butterfly species rely on one family of plants for survival. Often, these plants are found only in a particular habitat (such as prairie or tropical rain forest), and in a certain temperature range. So by tracking the butterfly population in a certain area, scientist can tell, for example, that the tall-grass prairie is quickly disappearing from a broad swath of North America. Or that the long-term weather patterns in an area have shifted over several decades.
Now Miller works weekends adding information from the McGuire Center collection into her database.