An unusual rabble of butterflies painting the sky white in some parts of the country has left Kenyans with unanswered questions.
Some see the swarm as a sight to behold, others think they are a menace, out to destroy their crops. Others find them annoying decelerators for vehicles on the road.
In this explainer, we speak to the chairperson for the Association of Kenyan Entomologists, Dr Muo Kasina, who gives insights on the butterfly migration and why it is happening now.
But first, what is a butterfly?
In our science lessons in school, we learnt about insect metamorphosis. This refers to the different stages of an insect’s life from an egg to becoming an adult.
Before a butterfly blooms, it was once an egg, and then it became a larva that scares most of you as it is what we call a caterpillar.
When a caterpillar grows, it forms a little new home which is the next stage of its life called a pupa, after which it emerges into a butterfly. Once it is an adult, it lives for only two weeks.
They are called Belenois aurota, commonly referred to by entomologists (people who study insects) as Caper white. These types of butterflies are found mostly in South Asia and Africa.
This is not the first time butterflies are migrating. They migrate every year. Unlike moths which fly at night, butterflies can only fly during the day.
These are local, or indigenous butterflies. It means that despite them migrating from one part of the country to the other, they did not come from outside our borders.
'Kill the butterflies': Kiambu farmers want farmlands fumigated due to infestation
There are different reasons for the migration of insects. And, climate change is one of those. As Dr Kasina explains, over the years, there are some cold parts of the country that have gradually become warm. Naturally, insects are not able to conserve energy. If it is cold, they will feel the cold, and the same thing happens when it is hot. They generally enjoy warm weather and this is the time that even their population increases. With the changes in climate, there is more productivity for insects because there is a shorter period for hibernation which usually happens during cold weather. This means that with their population increase, they migrate more visibly and frequently than before.
In other parts of the world, the International Union for Conservation of Nature says that climate change which causes wildfires also affects the migration of butterflies and sometimes, causes their death.
Yes, it has. Usually, migration happens from their natural habitat mostly in the plains at places like National Parks or where there is little distraction. The butterflies are now moving to buildings, roads and farmlands. Unlike locusts which are a bit heavy when flying and can go against the wind, butterflies are light and can easily be swayed towards the direction of the wind. The migration is also supported by the lack of rain because they can’t fly during the rains.
Dr Kasina says that they have a positive impact on people’s health. When people see them on the road and get excited, it boosts their mental health.
The downside however is on road users. When the rabble slows them down, people need to be careful not to cause an accident.
Apart from their short life span, human activities which the scientists discourage, cause premature death for the butterflies. Some are knocked down by vehicles and most of them are killed by insecticides, as farmers fear destruction of their crops. Entomologists assure that the species flying around the country are harmless to crops.
They are also useful in terms of pollination, which is the process of transferring pollen grains from the male part of a flower to the female part in order to cause reproduction for plants.
Do not spray pesticides to kill them. Also, for the next generation of butterflies, cutting down trees destroys their natural habitat. For communities that eat caterpillars, scientists say that harvesting caterpillars threatens the existence of the butterflies because they do not farm them.
