Nature on our doorsteps: Butterflies and the weather

Rosaleen Dwyer is the County Heritage Officer at South Dublin County Council – every week she gives us an insight into nature on our doorsteps and the beautiful biodiversity of its plants and wildlife.

BUTTERFLIES are cold-blooded creatures.

They cannot regulate their body temperature and so they need to draw heat from the sun to fly, search for food, and find a mate.

Butterflies need to be at a certain temperature before they fly.

Day-to-day weather conditions can have a huge effect on their activities, and in Ireland this is a real challenge.

They take time to warm up in the morning.

In its sheltered overnight spot, the butterfly begins by vibrating the muscles on its chest that operate its wings.

A butterfly will fully close its wings when it is too hot

This raises its body temperature enough to allow it to take flight and to find a sunny spot to warm up fully.

Its wings are like solar panels, absorbing and distributing heat from the sun to the rest of its body.

When it is cold, it will bask on leaves or flowers with its wings held flat to the ground beside its body, catching as much of the sun’s warming rays as possible.

They are often seen basking on dried, brown grass, or on sunny walls and stony footpaths.

These substrates heat up faster in the morning sun, allowing the undersides of the butterfly’s body and wings to also benefit from the warmth rising up underneath it.

As it warms up, the butterfly will change the angle of its wings.

It raises them halfway up over its body, reducing the area of the wings that are fully exposed to the sun and allowing some cooling air to circulate around its body.

If it gets too hot, it will close its wings completely, and it may also move to a shadier spot until it cools down.

Just like Goldilocks, butterflies like conditions that are not too cold and not too hot.

They can suffer from too much heat as well as from very cold conditions.

A changing climate will therefore bring further challenges to insects like these that are very sensitive to weather conditions.