What Do Monarch Butterflies Eat?
A monarch's diet changes completely between caterpillar and adult — one eats leaves almost exclusively, the other drinks liquid nectar. Both stages, though, depend on the same plant family in different ways.
Caterpillars: Milkweed Only
Monarch caterpillars are what's called a "specialist" feeder — they eat milkweed (Asclepias species) and essentially nothing else. A newly hatched caterpillar eats its own eggshell first, then moves straight to the milkweed leaf it hatched on, consuming leaves almost nonstop through five growth stages (instars) before forming a chrysalis. Without milkweed nearby, monarch eggs and caterpillars simply can't survive, which is why milkweed loss is tied so directly to falling monarch numbers.
Adults: Nectar From Many Flowers
Once a monarch becomes an adult, its diet opens up considerably — it feeds on nectar from a wide range of flowering plants, not just milkweed. Favorites include milkweed's own blooms, aster, goldenrod, Joe-Pye weed, and zinnia, especially plants that flower in late summer and fall when migrating monarchs need to build up fat reserves for the trip south.
