Expert: Swarms of butterflies not a bad omen, just mere migration

Butterflies are seen in the butterfly valley in Honghe Hani and Yi Autonomous Prefecture, southwest China's Yunnan Province, May 24, 2023. [Xinhua]

For the last few weeks, the skies have been beautified by swarms of butterflies. Some pause to savour the moment by taking pictures and videos.

However, while experts have said that it’s a normal migration, some people believe it is a bad omen.

Bad omen or not, Kenyans have been wondering what could be the cause of the migration.

Njoroge Ndung'u, entomologist and curator of invertebrates at the National Museums of Kenya, says the ongoing migration is not of all butterflies but of a specific species.

“The particular species is known as the Caper white or Brown-veined white. This species is largely white with a little black hence the noticeable white colour," says Njoroge.

He says the current migration has been triggered by the prevailing weather conditions that are very suitable in some regions.

Greener pastures

“So in essence, the butterflies are moving for greener pastures i.e. for food and egg laying. They lay eggs in areas where they are assured of food for their young ones. So the areas currently receiving rains since December and January are now rich with flowers and food plants for caterpillars,” he says.

However, Njuri Ncheke elders say that the sign of insects in January is a bad omen.

The Njuri Ncheke serves as the supreme governing council of elders for the Meru people of Kenya. Beyond its administrative function, it holds a significant judicial role, representing the apex of the Meru traditional judicial system, with its rulings extending across the entire community.

Julius Mbogori, an elder who runs a Njuri traditional court at Nchiru in Tigania West in Meru, says things will not be good in terms of food production, with the coming of the insects.

"When you see a lot of insects all over our vegetation, it means hunger will follow and it is advisable to plan for it. In the past when we witnessed this, hunger always followed and this won't be different unless there are measures taken to ensure food security. This is surely a bad omen. From March there will be less rainfall," says Mbogori

Jennifer Mutwiri, a retired teacher, echoes Mbogori's sentiments saying that, in the past, the sighting of the insects brought famine, so residents should be worried and perhaps stock up on food.

"I cannot remember which seasons but whenever they came, famine followed because we had less rainfall and less food in the granaries," says Mutwiri

However, Njuri Ncheke Supreme Council of Ameru Elders Secretary General Josphat Murangiri believes butterflies in January is a sign of climate change.

"Traditionally we do not see butterflies around this month. We normally see them in May, after the March-April rains. People should not be worried that hunger will follow. If there is sufficient vegetation, the butterflies mean there is plenty of food,” says Murangiri.

Dr Simon Gichuru, the chairperson of the elders in Murang’a County, says the butterflies are announcing an impending disaster.

“In the past, they have led to hunger and this time it will be worse as we might lack drugs to combat the larvae,” says Gichuru.

Isaac Litali, an elder from the Butsotso community in Western, says January is always hot but this year they have experienced a lot of rain that has brought butterflies and caterpillars.

He says the onset of butterflies signifies the abundance of food in the community as the insects appear during a harvesting season that occurs immediately after the rains.

“We normally see butterflies in plenty after we have harvested, especially beans. This signifies celebration of the efforts that farmers have put into producing food during the planting season,” he says.

However, he says that while butterflies signify happiness, too many of them may raise an alarm of tragedy happening in the community.

Some parts of the country like the North Rift have not reported the migration. Most farmers in the area are preparing their farms for planting.

According to the Nandi community's cultural beliefs, the sighting of butterflies symbolises the beginning of a dry spell and that the warm temperature is conducive for the adult butterflies to start migrating from West to East.

Benjamin Kitur, chair of the Kaburwo Council of Elders, believes there is a dry spell in the offing. However, there is hope as the season will likely be followed by heavy rains.

Kitur says the farmers should use the opportunity to prepare their farm for planting before the rains start.

Entomologist Njoroge says the general direction of migration is from North to South.

The Southern and Southwestern parts of the country as well as neighbouring countries of Tanzania, Rwanda, Burundi, DR Congo and Malawi, have been and are still receiving heavy rains.

“We have reports from contacts in Western Kenya, Rift Valley, Central parts of Kenya as well as far as Isiolo. So a big swathe of the country is experiencing the spectacular migration,” he says.

The biggest threat to these colourful insects is habitat loss.

“Important habitats are fast disappearing as they are turned into farmland and human settlements. Other equally significant threats include pesticide use and climate change. Butterflies being flower visitors often come into contact with residual pesticides sprayed on crops,” says Dr Njoroge. But he says farmers should not be worried.

“The caterpillar stages of the butterflies are extremely specific on what they feed on. They feed on the leaves of a few plant species in a family of plants called Capparaceae (Caper family, hence their common name). It comprises various wild shrubs and small trees. Unlike us who sometimes want to change from ugali to pizza, most of these species stick to a very strict diet.”

Entomologist Daniel Ochieng’ Gamba says some of the white butterflies are migratory and belong to the family Pieridae. The small all-white butterflies are the so-called cabbage butterflies, specifically Pieris rapae, while the small white with tinges of black at the edges of the wings is referred to as the pioneer white or the African cape (Belenois aurota).

“This species has been reported in South Africa to migrate for hundreds of miles up to the island of Madagascar. The butterfly’s migration in Kenya has not received adequate research to determine how far and where they migrate. Some observations have placed them crossing to Serengeti. But these are anecdotal evidence. Other butterflies are localised in specific areas where they are useful in pollination of plants,” he says.

Gamba adds that the causes of the migration of insects are attributed to several factors. Key to this is the innate ability to detect weather variability and react to them if they are not favourable to the insect.

“The insects usually migrate to increase the chances of successful reproduction in the new area that they are migrating, foraging for new sources of food and mating or search for mates,” he says.

Climate change   

According to Dr Subramanian Sevgan, a principal scientist from the International Centre of Insect Physiology and Ecology, the unusual weather patterns, which are linked to climate change, are responsible for this phenomenon

“Currently most parts of the country have been recording an unexpectedly high amount of rainfall from November to January. This is unusual. Increased rainfall and temperature variations during this time of the year may have triggered a favourable environment for the growth of vegetation which are breeding sites for butterflies and moths,” he says.

He adds that this is a strange occurrence whose developments need to be studied further to understand and monitor potential patterns and impact on the local ecosystem.

“It is strange to us as scientists since butterflies are rarely seen in January. This triggers the need for further investigations to see if this is going to be a trend in coming years,” says Dr Sevgan.

[Reports by Rosa Agutu and Phares Mutembei]