Monarch butterfly
Danaus plexippus
— Where the name comes from
Danaus is the mythical king of Argos; plexippus, Greek, “he who drives the horses”. The common name monarch was, on the most widely held theory, a colonial nod to William III of Orange, for the orange colour.
— Facts
- Group
- Insects · Insecta
- Order
- Butterflies and moths
- Habitat
- Grassland, field margins, anywhere milkweed grows
- Range
- North America; introduced populations elsewhere
- Size
- 9–10 cm wingspan
- Diet
- The caterpillar eats only milkweed; the adult, nectar
- Lifespan
- 2–6 weeks, but the migrating generation lives 8 months
— Characteristics
- 01
The caterpillar sequesters the toxic cardenolides of the milkweed and keeps them as an adult.
- 02
It makes a 4,000 km migration to the firs of Michoacán.
- 03
It navigates by a sun compass corrected by the circadian clock in its antennae.
— What sets it apart
No monarch makes the whole journey twice. The butterfly that leaves Canada in autumn reaches Mexico, overwinters, sets off again and dies along the way; it takes three or four generations to get back north. And yet the individuals coming down in autumn reach the same trees as their great-grandparents, which they never knew. The route is not learnt: it is inherited.
