Across a Swiss meadow and into its forested edges, the drone dragged a jumbo-size cotton swab from a 13-foot tether. Along its path, the moistened swab collected scraps of life: some combination of sloughed skin and hair; mucus, saliva, and blood splatters; pollen flecks and fungal spores.

Later, biologists used a sequencer about the size of a phone to stream the landscape’s DNA into code, revealing dozens upon dozens of species, some endangered, some invasive. The researchers never saw the wasps, stink bugs, or hawk moths whose genetic signatures they collected. But all of those, and many more, were out there.

The researchers, from the Swiss Federal Institute for Forest, Snow and Landscape Research, were field-testing a new approach to biodiversity monitoring, in this case to map insect

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