Butterflies in Singapore have decreased in both number and variety since the 1980s but conservation efforts launched in recent years have managed to partly stem the loss.
Excluding new butterfly species, some 117 are now believed to be extinct; there have been no reliable observations of them for at least the past two decades. A comparison with past recorded checklists shows there are now 306 species, down from 386 in the 1950s to 1980s.
Citing these figures, butterfly expert Khew Sin Khoon, who is also an honorary research affiliate at the Raffles Museum of Biodiversity Research, said the trend was mainly due to the loss of habitats.
"Butterflies are tightly correlated with plants, and as Singapore developed, the habitats that they prefer may have been destroyed... Some of the caterpillar host plants may have (also) gone extinct," he said.
It is not known when the sharpest decline in the number of butterfly species took place but Mr Khew said the peak of development occurred in the 1970s and 1980s when tracts of land were cleared to make way for new homes.
Ecologist Anuj Jain, 29, said that over the years, developments around forests have resulted in what he calls "fragmented forests".
"If the forest is big, you have a bigger interior but if you have smaller forests, it means there are more areas for light exposure," said Mr Anuj, who heads the Butterfly Interest Group at Nature Society of Singapore (NSS). "Although some species are adaptable to light conditions, most butterflies like to hide in darker areas."
More recently, the increased fumigation in residential areas is also threatening butterflies and caterpillars, said Mr Khew.
A National Environment Agency spokesman, however, said that while fogging could have some impact on other non-target insect species, a pragmatic and balanced approach that prioritises human life in outbreak situations should be adopted. "Insecticide use should be reduced during non-epidemic periods in order to prevent the development of resistance and minimise the impact on other species," he added.
The decline in the number of butterflies is keenly felt by butterfly enthusiast and expert Steven Neo, 63, who started catching butterflies when he was still in school. He recalled the days when he was living in a kampung in Lorong Chuan that was surrounded by forests.
"Back then, when there was more greenery, butterflies can be found in every corner... Now the parks are well manicured but the variety is very much reduced," said Mr Neo, who is semi-retired and works as a property manager.
However, there have been measures to conserve Singapore's biodiversity over the years. The National Parks Board (NParks) has partnered the community to develop community gardens and butterfly trails.
For example, the agency was one of the partners which supported NSS when it launched the Butterfly Trail at Orchard project in 2010.
The 4km trail stretches from the Singapore Botanic Gardens to Fort Canning Park. The initiative has borne fruit since its launch as the number of butterfly species spotted along the trail has increased from 20 to 62.
Dr Geoffrey Davison, the covering director of the National Biodiversity Centre at NParks, said Singapore's butterfly diversity compares favourably with countries like France which has 250 species.
Sentosa Development Corporation started an initiative in 2006 where more than 20 wildflower species were reintroduced to other parts of the island.
"Some of these wildflowers are important nectar plants for butterflies," said Ms Grace Lee, environment management director of Sentosa Leisure Management.
However, Mr Anuj feels that conservation is more than just increasing the number of butterfly species. Such efforts should instead work towards targeting butterflies that are threatened.
Butterfly enthusiast Samuel Liu, 25, feels that keeping nature reserves "as they are" would help to protect more butterflies in the forest areas.
"If some species go missing, it will affect the balance of the ecosystem. It would be sad if we lose them."