Common Green Lacewings: these tiny insects build loosely-woven cocoons that measure just 3-6mm (about 1/8 to 1/4 inch) in diameter
Each lacewing spends about 5 days maturing inside its cacoon, and then it cuts an opening in the top and emerges as a fully-developed adult.
Above: a common green lacewing emerging from its cocoon
Green lacewing larvae (genus Chrysopidae) are also known as "aphid lions," because they're voracious predators that often feed on aphids. They've also been known to prey upon caterpillars, leafhoppers, planthoppers, thrips, spiders, mites, and insect eggs, which is why they're widely used to help eradicate pests in agricultural contexts.
Once the lacewing nears the end of its larval stage, it builds a small cacoon out of silk and then tucks itself inside, allowing the pupal phase to begin. Its tiny green body is often partially visible through the thin, loosely-woven walls of the cacoon.
Above: a lacewing developing within its cocoon
These breathtaking photos of a lacewing climbing out of its cacoon were taken by a Danish photographer named Frederik Leck Fischer.
Above: the lacewing preparing to emerge
When the insect initially emerges, its wings and antennae are still compactly folded down against its body, and the wings have a dark, shriveled appearance that makes them almost unrecognizable.
Above: the fully-developed lacewing waiting for its wings to expand
The wings then gradually expand until they have reached their full size, which usually takes about an hour or two.
Above: the same lacewing just a few hours later
Fischer's photographs provide a stunning account of the entire process.
Above: close-up of a common green lacewing
This is a rewritten version of a post that I originally published three years ago.
Sources & More Info:
iNaturalist: Common Green Lacewing
University of California: Family Chrysopidae
Texas A&M: The Green Lacewing
Washington State University: Lacewings
Tennessee State University: Insect Predators: Green Lacewings (PDF)
Pacific Pests and Pathogens: Green Lacewings