Monarch Butterfly Facts
for Kids

Monarch butterflies migrate up to 4,800 km (3,000 miles) one way — from breeding grounds across Canada and the United States to overwintering forests in central Mexico. This is one of the longest migrations of any insect species on Earth.

Monarchs navigate using a time-compensated sun compass in their antennae combined with sensitivity to Earth's magnetic field. Remarkably, no individual butterfly makes the complete round trip — the ability to find the ancestral wintering sites in Mexico appears to be genetically encoded.

Yes — monarch butterflies are toxic to most predators. As caterpillars, they feed exclusively on milkweed plants, which contain cardiac glycosides (heart toxins). These toxins accumulate in the caterpillar and carry over into the adult butterfly, making the whole animal distasteful or dangerous for birds and other predators.

Monarch populations have collapsed by roughly 80% since the 1990s. The main causes are: widespread loss of milkweed plants (the only plant monarchs breed on) due to herbicide use in agriculture; deforestation of their Mexican overwintering forests; and climate change disrupting migration timing.

Viceroy butterflies are a separate species that mimic the monarch's orange-and-black pattern to benefit from the monarch's toxic reputation with predators — a phenomenon called Batesian mimicry. Viceroys are slightly smaller and have a black line crossing the hindwing that monarchs lack.