We didn’t see many monarchs in Texas last month — not because it is a Republican state but because the cold snap had presumably sent these amazing migratory butterflies scuttling south to warmer climes. Only one or two non-migratory ones had stayed around to remind us what we had missed.
These creatures over-winter in the mountains of Mexico and set off in the spring to fly northwards, pausing to breed, then the offspring in their turn set off again northward, pausing to breed and thus they go, a step per generation, all the way to southern Canada. Come the autumn they all turn southward heading back to their wintering grounds where no individual has ever been before — how clever is that?
They lay their eggs on milkweed, the food plant of the caterpillar, which contains alkaloids which confer the gift of nastiness to the way they taste and which make them poisonous to predators. That helps!
Queens are also milkweed butterflies — we saw more of them — they are also migratory, presumably also following the milkweed season north but less is known about their migratory habits. They are similar to monarchs but are darker and more russety and have no black veining when viewed from above.
The viceroy butterfly, below, looks much more like the monarch, apart from those straight black lines which transect the black veins towards the back of their wings. This is the impersonator! They do not lay their eggs on milkweed, they do not assimilate the poisonous alkaloids of the milkweed and presumably taste quite good to birds, reptiles and hungry amphibians. They are just mimics, surviving and prospering because they look like something that tastes nasty! Their ancestors didn’t have to practice on a poisonous plant that probably killed some of them. Now that is really clever!