‘Goldilocks’ weather to help butterflies flourish

‘Goldilocks’ weather to help butterflies flourish

17 September 2025

IT really has been a bumper year for butterflies. Throughout the summer it has been difficult to miss them flitting from place to place in gardens and in the countryside.

Butterflies are much-loved, unlike many other insects such as wasps and beetles.

Reproduction is the prime function of adult butterflies and their success is measured by their ability to lay eggs on a suitable food plant.

In due course the eggs hatch into caterpillars, the juvenile or larval stage. The caterpillar stage can last for much longer than the fragile adult stage that we see flying in the summer.

Adult butterflies normally feed on nectar, whereas the caterpillars voraciously munch their way through leaves of a variety of plants including cabbage, nettles and other plants we tend to think of as ‘weeds’.

Butterflies are attracted to gardens which have nectar-rich plants such as buddleia and verbena, and that is where many of us tend to see them. 

One of our most common butterflies is the Small Tortoiseshell. Beautiful and easily recognised, it is a welcome sight.

Like most types of living organisms, the different types of butterflies are most likely to be found in their favoured habitats.

For example, the Silver-washed Fritillary, one of our largest and most beautiful butterflies, will be more easily spotted in woodland clearings or woodland fringes during the summer months where they feed on a range of wildflowers including brambles.  

The photograph of the Red Admiral shows another feature of butterflies. Most people recognise the Red Admiral by the striking band of orange-red which runs across the upper surface of the wings. However, as in most butterflies, the upper and lower wing surfaces are different.

When resting, and often when feeding, butterflies have their wings folded vertically above their body.  In this position, it is the undersides of the wings which are exposed.

The drab colours of the undersides of the wings in many species provide excellent camouflage for protection at a time when the butterfly is immobile and very vulnerable to predators.

While many people are reasonably familiar with a small number of species of butterfly, some will be surprised to learn that in Northern Ireland well over 20 species can be found.

But what has caused the high numbers this year, particularly when 2024 was so poor for butterfly numbers?

The weather was a major factor, and 2025 has been a ‘goldilocks’ year with a damp and warm spring providing good growing conditions for the caterpillar food plants, in addition to a warm and sunny summer which was ideal for the adults.

However, the overall trend is disappointing with the numbers of many species decreasing in the longer term.  Many factors are involved, including habitat loss, the use of pesticides and, of course, global warming which is playing havoc with our ‘normal’ weather patterns.

While, individually, we cannot do much about the weather, we can grow butterfly-friendly plants in our gardens and leave the occasional little bit of ‘wilderness’ for the caterpillars if we have the space.