How one man repopulated a rare butterfly species in his backyard

Once situated, the caterpillars began their long, drawn-out process of maturation.

After about 3-4 weeks, a caterpillar pupates and forms a chrysalis (or outer shell). The insect liquifies itself inside, and either develops into a into butterfly in about two weeks, or stays dormant for up to two years (this delayed development is called "diapause").

"It’s like a long hibernation," says Wong. "And when it’s over, they emerge as adult butterflies."