Mesocosmo (Butterfly House), Natural History Museum of Salento

The Natural History Museum of Salento was founded in 1982 outside the town of Calimera, in the province of Lecce, at first as a place for exhibitions and teaching. In 1996 the Naturalia cooperative took over its direction and management and turned it into a research centre; the museum also runs a recovery centre for injured, confiscated or endangered wild animals that can no longer survive on their own.

The Mesocosmo grew out of an idea by Naturalia. It was built under the ERDF 2007-2013 regional operational programme, through action 4.2.1 for the upgrading of the museum, begun in March 2012, with additional private funding from the cooperative. A local news article dated 4 September 2018 announces its opening to the public. A 2020 article already describes the greenhouse, its Butterfly House and the small planetarium nearby, and in April 2023 the Salento press announced that visits would resume on Sunday 2 April. The museum presents it as unique of its kind in southern Italy and as one of the largest butterfly houses in Europe, and the Mesocosmo serves exhibition, teaching and research in ecology, ethology and physiology alike.

The Mesocosmo is a twin-span greenhouse 35 metres long, 19 metres wide and 6 metres high, with 630 m² open to visitors (600 m² according to a 2020 article). Its polycarbonate roof filters about 30 per cent of the solar radiation from the south, and a screen of cypresses to the north and poplars to the south shelters it. Inside there are no planters or edged beds: the plants grow in the ground, and visitors follow a U-shaped path laid on a grassed grid that lets herbaceous plants grow through.

The climate is hot and humid: 27 to 30 °C by day and 24 °C at night according to the museum (26 to 27 °C according to a 2018 article), with relative humidity above 80 per cent. An irrigation network simulates tropical rain, a drainage layer one metre deep feeds a 15,000-litre water tank, and a forced-induction cooling system powered by renewable energy uses the low temperature of deep groundwater to keep the two spans from overheating.

The rainforest was chosen because, in the museum's words, it is the most endangered environment on the planet. The plants, which the sources consulted do not name, were selected for their systematic, conservation, economic and food value, with a share of fast-growing pioneer species. The tropical butterflies come from specialist farms that collect sustainably, which the museum says supports an ecological economy in tropical regions; the 2023 press also mentions exotic birds.

The greenhouse works as an ecosystem: earthworms, crickets, stick insects, beetles and millipedes break down organic matter, and mantises and freshwater crabs also live there. Aphids are kept down by ladybirds (Adalia bipunctata, Cryptolaemus montrouzieri) and lacewings (Chrysoperla carnea), and mosquitoes by fish, Gambusia affinis and Poecilia reticulata.

The Mesocosmo opens only from April to October, following the museum's calendar, and visits can be made with specialist guides. It stands within the museum grounds, surrounded by a holm-oak wood that recalls the charcoal burners of old Calimera.

A visit continues through the museum's galleries of astronomy, mineralogy, palaeontology, palaeoanthropology, entomology, malacology, marine biology and taxidermy, and the small planetarium. Stepping from the steamy greenhouse into the shade of the holm oaks sums up the place, between a recreated tropical forest and the Salento landscape.