All about the Monarch Butterfly
The Monarch is a highly evolved migratory machine with specialized body parts – polarized eyes, multi-purpose antennae and tactile sensory receptors on its head, legs and feet – that help it navigate and migrate long distances. They are also migratory pollinators!
Even with all their highly evolved parts and abilities for navigation and orientation, the Super Generation of Monarchs has a long way to go – thousands of miles – and to a place they’ve never been to before, yet with pinpoint, navigational accuracy. To save energy on this extraordinary journey, they take advantage of thermal waves found high in the sky, store fat reserves at a remarkable rate and save mating until they reach their destination where they will rest for many months in the mountaintop, evergreen trees of central Mexico. The question remains, how do they know to head for those specific mountaintops, just a few peaks amongst many?
The adult butterfly weighs less than half a gram and has four wings and six jointed legs. Their large compound eyes contain thousands of tiny circles called ommatidia, which gather light and process visual information.
Monarchs also perceive ultraviolet and polarized light – light waves that move in only one direction and they sense that direction, possibly using it to migrate. Females are darker in colour and have wider veins. Males are slightly smaller with two black spots near the bottom of each wing and special glands that release pheromones.
Monarchs get much of their taste and smell from chemoreceptors scattered across their bodies. Butterflies detect smells mostly through their antennae. They sense the odor of nectar – and females the odor of the males’ pheromones – through special glands on their wings. Females have more chemoreceptors on their legs to help them find milkweed plants on which to lay their eggs.
Touch, sensed through hairs (tactile setae) that cover most of their bodies, is important to both young caterpillars and mature adults. These hairs relay information about movement – important for flight – to sense wind, gravity and the position of other body parts. Hair on the Monarch’s antennae senses both smell and touch.