Large numbers of yellow and white butterflies have recently been spotted flying across several parts of Sri Lanka, including Colombo, attracting public attention and curiosity.
Videos and photographs showing large swarms of butterflies moving in the same direction across areas such as Colombo, Galle and Ratnapura have been widely shared on social media.
According to an explanation published by Fact Crescendo Sri Lanka, the phenomenon is a seasonal butterfly migration associated with monsoon rainfall, changes in vegetation and breeding patterns.
Experts say butterfly migration in Sri Lanka generally occurs during two periods: a major migration between October and December and a smaller migration between March and April.
Rainfall associated with monsoon conditions encourages the growth of plants that provide food and suitable breeding grounds for butterflies. This contributes to an increase in their population. As their numbers grow, butterflies move to other areas in search of suitable host plants for laying eggs and to reduce competition for resources.
Among the prominent migratory species are the Lemon Emigrant, Mottled Emigrant, Lesser Albatross and Common Albatross.
A study published in the scientific journal Taprobanica in 2024, conducted by a team of researchers including Professor Kapila Dissanayake of Sabaragamuwa University, identified major butterfly migration routes across Sri Lanka.
Based on data collected from 60 locations, the study identified a major migration route extending from the southeast towards the northwest.
Researchers observed that butterflies travel approximately 280 kilometres from the Kumana National Park area to Wilpattu within three to four days.
Albatross butterflies have been estimated to travel at an average speed of around 11 kilometres per hour.
Speaking to Fact Crescendo, the former president of the Butterfly Conservation Society of Sri Lanka explained that seasonal rainfall encourages the growth of host plants needed for butterfly breeding, particularly in the dry zone.
She said the resulting increase in butterfly populations leads to their movement across the island, influenced by wind patterns and the distribution of vegetation.
She also said she had personally observed Lemon Emigrant and Mottled Emigrant butterflies flying from east to west in the Borella area of Colombo.
Are the Butterflies Flying Towards Sri Pada?
The seasonal migration has once again drawn attention to the traditional belief that butterflies travel towards Sri Pada, also known as Butterfly Mountain.
Experts explain that some butterfly species display a behaviour known as “hill-topping”, in which they gather around elevated locations to find mates.
However, research indicates that most migrating butterflies move towards the northwest rather than specifically towards Sri Pada.
Can Butterfly Migration Predict a Natural Disaster?
The large-scale appearance of butterflies has also prompted speculation that the phenomenon could be a warning sign of an impending natural disaster.
However, researchers say there is no scientific evidence to establish butterfly migration as a predictor of major natural disasters.
Although butterflies are sensitive to changes in atmospheric pressure, humidity, temperature and wind patterns, their migration should not be interpreted as an official warning of an approaching disaster.
Experts also warn that climate change, irregular rainfall patterns and the spread of invasive plant species pose significant threats to butterfly populations.
Research suggests that despite the large numbers currently being observed, overall butterfly populations and the scale of migration have declined compared with the past.
Therefore, experts say the current phenomenon should be understood as part of a natural seasonal ecological cycle rather than a sign of an impending disaster.
