08/31/2026
Happy Mystery Monday! 🔎 Can you guess what is pictured in photo #1?
The answer to last week's mystery is monarch butterfly caterpillar, Danaus plexippus, pictured in photo #2.
The monarch butterfly caterpillar, Danaus plexippus, is one of the most recognizable caterpillars in North America, with bold bands of black, yellow, and white and two pairs of black, flexible tentacles. In Maryland, adult monarchs may begin arriving in spring, but caterpillars are especially noticeable in late summer, with many found during August and September as successive generations move through the region.
Monarch caterpillars are specialists and can eat only milkw**ds, which provide more than just food: as caterpillars eat the leaves, they take in defensive chemicals produced by the plant that help make both the caterpillar and adult butterfly distasteful to many predators. Asclepias species like common milkw**d, swamp milkw**d, and butterfly w**d are among the native Maryland species that provide food for developing caterpillars.
Females usually deposit their tiny eggs individually on milkw**d leaves and, after hatching, the caterpillar spends roughly two weeks doing little besides eating and growing. During that time it passes through five stages, called instars, shedding its skin each time.
When fully grown, the caterpillar leaves its milkw**d, attaches itself to a sheltered surface, hangs in a distinctive “J” shape, and transforms into a jade-green chrysalis decorated with tiny metallic-gold markings. About two weeks later, an adult monarch emerges and, for Maryland’s late-season generation, that transformation may be the beginning of an extraordinary migration south toward the mountains of central Mexico.
Mystery Monday is sponsored by the Spy Newspapers and Adkins Arboretum.
