Shrouded in the mist of Bengali month Poush, Jahangirnagar University’s (JU) lush green campus comes alive with festive energy.
Children, teenagers, and young adults alike wear colourful butterfly motifs on their faces, clutch festive banners, and gaze around in wonder. The occasion: the annual “Butterfly Fair.”
Yet beneath the vibrant celebration lies a profound environmental concern. Just beyond Dhaka, this picturesque campus — once unparalleled in its natural beauty and biodiversity — is witnessing a slow but alarming decline. Where over 110 butterfly species once fluttered freely, their number has now dwindled to just 72.
Experts warn that this local crisis mirrors a global decline in butterfly populations. A falling butterfly population signals an ailing environment and serves as an early warning of ecosystem collapse.
Host plant scarcity and the struggle for survival
According to Dr Monwar Hossain, professor of Zoology and a leading butterfly researcher, when the first Butterfly Fair was organized in 2010, JU was known as a “butterfly sanctuary.” The campus, filled with shrubs, creepers, and shaded woodland, supported around 110 species. Today, that number has dropped to 72, with losses continuing year by year.
“Shrubs and small plants have declined,” he says. “The scarcity of host plants disrupts the butterfly life cycle. Many species have already disappeared from the campus.” Urban development, road expansion, tree felling, and excessive insecticide use have severely damaged butterfly habitats.
A 2025 study published in the Asian-Australasian Journal of Bioscience & Biotechnology reveals more alarming trends. Of 107 potential host plants, only 12 remain suitable for larval development, and these are fragmented across the campus—creating what researchers call “host plant fragmentation.” The study’s authors, Shraboni Das, Muntahena Ruhi, Mohammad Sohel Abedin, and Dr Monwar Hossain, warn: “If host plant shortages are not addressed, even the remaining 72 species may not survive.”
Why are butterflies declining?
The butterfly decline at JU reflects both local and global environmental crises. Habitat destruction, indiscriminate clearing of shrubs, and urban expansion reduce available green spaces. The loss of host plants prevents eggs, larvae, and pupae from completing their life cycles.
Chemical sprays intended to control mosquitoes also destroy butterfly eggs and larvae. Climate change disrupts seasonal patterns and temperature cycles, further hindering reproduction.
Artificial lighting at night disorients butterflies, and rapid urbanization threatens shrub-dependent species in city areas.
Globally, butterfly populations are plummeting. Over the last three decades, numbers have dropped by 50–75% worldwide. The UK’s Big Butterfly Count shows even common species are now endangered. The famous Monarch butterfly in the US has declined by 85–90%. In South Asia — India, Nepal, Sri Lanka — shrub-dependent species are disappearing rapidly. Experts describe butterflies as the “canary in the coal mine” — early indicators of environmental distress.
Dr Monwar explains that gradual loss of host plants, chemical pollution, climate pressures, and shrinking habitats lead butterflies to disappear locally, retreat to other areas, or become extinct entirely. This silent disappearance signals deep ecosystem disruptions, often noticed too late.
‘The invisible heroes of environment, economy, and biodiversity’
Butterflies are second only to bees as pollinators, playing a critical role in the production of fruits, flowers, and vegetables, thereby sustaining agricultural economies. Their presence indicates environmental health — where butterflies thrive, ecosystems are generally balanced.
They are also vital to food chains: their larvae feed birds, frogs, crickets, and small mammals. Declining butterfly populations can trigger cascading food shortages.
Additionally, butterflies support plant dispersal, seed production, and genetic diversity, making them indispensable for overall biodiversity. Beyond ecology, they enrich natural beauty, environmental education, and children’s understanding of nature — silent guardians of ecosystem balance.
How to bring back the colourful wings
Restoring butterfly diversity requires scientific planning and long-term conservation strategies. Experts recommend:
- Host Plant Reintroduction: Expand milkweed, lantana, cassia, calotropis, and citrus trees to support larvae and adult butterflies.
- Control Shrub Clearing: Protect areas where larvae thrive.
- Environmental Assessment for Construction: Make eco-friendly planning mandatory for any campus roads or buildings.
- Chemical Control: Establish “No Chemical Zones” in butterfly hotspots.
- Create Butterfly Corridors: Connect fragmented greenery to allow free movement and reproduction.
- Research and Monitoring: Collect species-specific data regularly to guide long-term policies.
Global examples show success: the UK’s Rewilding Program restored shrubs and shrubs, reviving endangered species; the US established a 2,500 km Milkweed Corridor for Monarch butterflies; Sri Lanka set up a dedicated Butterfly Forest Reserve on a university campus. JU could adopt any of these models to restore its lost butterfly diversity.
Butterfly Fair: A call for nature conservation
The Butterfly Fair is more than a festival — it is a platform for environmental awareness. Activities include drawing, butterfly identification, quizzes, puppet shows, kite flying, and recognition awards like the “Butterfly Award” and “Young Enthusiast Award” for contributions to butterfly conservation.
Dr Monwar Hossain emphasized: “Where butterflies exist, life thrives. When butterflies vanish, nature itself stands still.”
Without immediate action to protect host plants, conserve shrubs, and safeguard green areas, the colourful wings of butterflies may soon exist only in books and photographs.
