Monarch Butterfly
Danaus plexippus
Monarch Butterfly (Danaus plexippus) is a species in the genus Danaus, family Nymphalidae, order Lepidoptera.
Scientific classification
| Rank | Taxon |
|---|---|
| Domain | Eukaryota |
| Kingdom | Animalia |
| Phylum | Arthropoda |
| Class | Insecta |
| Order | Lepidoptera |
| Family | Nymphalidae |
| Genus | Danaus |
| Species | Danaus plexippus |
Description
The monarch is a large nymphalid butterfly with orange wings veined and bordered in black. Larvae feed almost exclusively on milkweeds (Asclepias), sequestering cardenolide toxins that persist into the adult and make it unpalatable to birds; the conspicuous colouring advertises this.
Migration
The eastern North American population performs one of the longest insect migrations known. Butterflies emerging in late summer enter a reproductive diapause and fly up to about 4,000 kilometres to a small number of overwintering sites in the oyamel fir forests of central Mexico, where they cluster in enormous aggregations. In spring they move north and breed; it then takes three or four successive generations to recolonise the northern range.
No individual completes the round trip, so the route cannot be learned. Orientation uses a time-compensated sun compass, with the circadian clock located in the antennae rather than the brain, supplemented by a light-dependent magnetic sense.
Conservation
The migratory populations have declined substantially, and the species was assessed as Vulnerable in
- Loss of milkweed from agricultural landscapes, degradation of the overwintering forests, and
climate effects on the timing of the migration are all implicated. The species as a whole is not at risk — non-migratory populations exist elsewhere — but the migration itself is.
References
- Reppert, S. M. and de Roode, J. C. (2018). Demystifying monarch butterfly migration. *Current
Biology* 28.
- Walker, A. et al. (2022). Danaus plexippus. IUCN Red List assessment 159971.