Permanent butterfly house in the Botanic Gardens

Orange-white, black-purple or translucent as a sheet of glass: dozens of butterfly species have been fluttering through the Botanical Garden's new butterfly house since May of 2019. Prior to the construction of the current permanent garden, an existing greenhouse was converted into a butterfly paradise before the start of every summer.

As Wim Kersten – biologist and resident butterfly expert at the Botanical Gardens – explains, it took a lot of man hours to convert the greenhouse every year. ‘Building up and tearing down the butterfly garden took us eight weeks in all.’ However, the temporary butterfly garden had another more serious drawback. It didn't offer the necessary capacity to raise permanent butterfly populations. Wim: ‘We couldn't raise all the various species in a sustainable way. That's unfortunate, especially in terms of education. You can't show visitors the entire life-cycle from egg to butterfly.’

A temporary butterfly garden just wasn't an option anymore, in other words. The Botanical Gardens finally decided to raise money for an actual butterfly paradise in 2018. They did so with the support of the Utrecht University Fund, which incorporated the project in the annual Funding the Future campaign. The result? 185 donors raised a total of 7,726.96 euros. The K.F. Hein Fund, an equity fund allied with the Utrecht University Fund, also donated 6,000 euros to the project. These contributions, together with other generous donations, helped make the butterfly house a reality in no time.

Our very own butterfly population

The butterfly garden has been one of the Botanical Garden's most popular attractions since its official opening. In fact, half the Garden's visitors travel to Utrecht to see the butterflies. The butterfly house also attracts regular visits from schools and has become a hotspot for butterfly photographers. Wim and the other volunteers also love the new butterfly garden. ‘I'm really grateful. We're getting weekly shipments of between 50 to 100 pupae from the Philippines, Kenya and Costa Rica, which means we can now raise our own populations.’

We're getting weekly shipments of between 50 to 100 pupae from the Philippines, Kenya and Costa Rica, which means we can now raise our own populations

Mail-order butterflies? ‘Definitely! We get our butterflies from butterfly farms. They're usually located in villages near the forests where the butterflies live. The locals occasionally catch female butterflies, which can easily lay up to 200 eggs. They wait till the eggs have grown into caterpillars and pupated, and ship them over here. In addition to helping us and all other butterfly gardens in the Netherlands, this trade also offers an economic incentive to conserve the local forests. And, perhaps even more importantly: butterflies, with their wealth of colours and patterns, tell the story of biodiversity and its crucial value. Every part of our ecosystem plays its own key role. That also goes for butterflies. Butterflies pollinate flowers and plants, and the females' eggs and caterpillars that hatch from them are an important source of food for other species.’

I offer visitors tips on making their own garden more butterfly-friendly

Unfortunately, biodiversity is declining at a startling rate in both the Netherlands and wider world. Wim: ‘That's bad news: like us, butterflies are also dependent on biodiversity. Butterfly caterpillars are picky eaters and usually only eat one or a handful of plant species: their host plant. Butterflies specifically seek out these plants in order to lay their eggs. If these plants go extinct, the butterfly species that depends on them is likely to follow. That's why it's so important to get our visitors – and, more importantly, children – interested in biodiversity and encourage them to help build a more diverse environment. For example, I offer tips on making their own garden more butterfly-friendly.’

Living project

There are twelve butterfly gardens in the Netherlands. So what makes the Botanical Gardens butterfly garden so unique? Wim: ‘The personal interaction. The butterfly gardens in major zoos are really large. Visitors tend to walk through them and think: well, that was nice. We regularly have volunteers that can explain and show you all sorts of interesting things. Our butterflies are also very active. The pupae hatch right in front of our visitors' eyes, and the butterflies flutter from plant to plant. It's a perfect opportunity to see them from up close and take some great pictures.’

Although the butterfly house is now finished and the net has been installed, there's still more work to do, Wim explains. ‘The butterfly house is a living project. The caterpillars eat the leaves, so we're constantly putting in new plants and farming new butterflies.’ So what's Wim's biggest wish? ‘I'd love to import a rare species like the birdwing butterfly and grow our own population here in Utrecht.’