Nature on our doorsteps: Sunshine and butterflies

During the recent very warm weather, there appeared to be a noticeable increase in the number of butterflies.

Butterflies are cold-blooded insects. They cannot regulate their own body temperature, so they need to absorb heat from outside of their body.

This heat is essential, as it is needed to warm up the insects before they can fly.

Butterflies absorb light energy from the sun. When the insect is basking in the sunshine, their open wings act like mini solar panels, warming up the muscles that make the butterfly’s wings flap.

In cool and overcast conditions, this warming-up process takes much longer. This is why butterflies are not very active in dull weather.

In cool weather, butterflies often warm up by sitting on rocks or paths which have absorbed some heat from the sun

However, because their wings absorb heat much faster than their bodies, butterflies can quickly overheat in very hot sun. To avoid this, they close their wings.

They can also release excess heat through the veins in their wings, helping the butterfly cool down whenever it needs to.

Weather conditions also affect how much nectar is produced by the flowers that the butterflies visit. Cold, wet weather slows down nectar production, while warmer temperatures increase its flow.

An extreme rise in temperature however, particularly during drought conditions, slows down or even stops nectar production altogether.

So, just as with Goldilocks, butterflies and other pollinators prefer conditions that are not too hot and not too cold.