Viceroy butterfly (Monarch look a like)

Monarch Butterfly

The Viceroy Butterfly (Limenitis archippus) is a North American butterfly with a range from the Northwest Territories along the eastern edges of the Cascade Range and Sierra Nevada mountains, southwards into central Mexico. I photographed this one in the Katherine Albertson Park in Boise Idaho.

Its wings feature an orange and black pattern, and over most of its range it is a Müllerian mimic with the Monarch butterfly (Danaus plexippus). The viceroy’s wingspan is between 53 and 81 mm.  It can be distinguished from the Monarch by its smaller size and the postmedian black line that runs across the veins on the hindwing.   It was originally believed that the Viceroy was a Batesian mimic of the three other species, and presumed edible or only mildly unpalatable to predators, but this has since proven not to be true.

The caterpillar feeds on trees in the willow family, including willows (Salix), and poplars and cottonwoods (Populus). The caterpillars sequester the salicylic acid in their bodies, which makes them bitter, and upsets predators’ stomachs. As further protection, the caterpillars, as well as their chrysalis stage, resemble bird droppings. Adults are strictly diurnal, flying preferentially in the late morning and early afternoon. I was able to photograph this butterfly in the early morning.  It spend a good deal of time warming itself on the rails of a bridge, before it flew to the leaves.