Eerie tales of Mupli beetle invasion in Kerala: Are insect-human conflicts intensifying in a warming world?

We have become familiar with floods, landslides, crop loss and diseases as parcels of the rainy season but are there more? As water disperses life into nature, it rejuvenates the macro world of insects. With lush vegetation and other bountiful resources supporting their growth, these grimy creatures flourish.

Certain events cause people to label insects as ‘creepy crawlies’. One such instance is the unsettling and stomach-turning appearance of Mupli beetles!

Although insects play a crucial role in the ecosystem, when these creatures become a nuisance, they can easily instill fear and drive away an entire human population. This is what has happened with families in Ponkunnam and Thodupuzha of Kottayam and Idukki districts in Kerala. 

Beetles, moths, fireflies and bugs arrive like unwanted guests during the monsoon. And sometimes they can be more than just a menace. In places like Kerala, they become destructive economically, ecologically and socially. 

They make a hushed entry with just a couple of individuals. Soon, a swarm swoop down and develop colonies like beehives on the walls.

These detritivorous darkling beetles (Luprops tristis) belong to Tenebrionidae family with flattened or cylindrical body and segmented antennae.

Locally, they are known as kotteruma or karivand due to their appearance, whereas the word ‘Mupli’ is derived from an infested forest area in Muplium in central Kerala, where they were first identified. Ola prani is another designated name for these invaders as they are fond of coconut leaves.

Tropics are their safe haven and this explains their selective preference for Kerala. The main home range extends from Afrotropics, Asia to Papua New Guinea. Technically being harmless to humans, rubber plantation litter belts are their favourite feeding spots, munching away the tender leaves of rubber plant.

Their lifecycle is really intriguing and crucial to their invasion strategy. The adult undergoes dormancy in dark, undisturbed locations for nine months. The young adults (larvae) having soft body become resilient residents of dry fallen decaying leaves of rubber plantations. These unattended stacks of leaves help kick-start their rapid reproductive activity around months of April-May through intensive feeding. After this, they grow and shroud themselves away in buildings and wait for the monsoon to wage a war. 

The major concern is drenching of piled up rubber leaves where these beetles take up the refuge. They always visit or bombard houses in hordes — about 4.5 million individuals under a single roof.

These beetles unexpectedly cause disturbances to residents as adults drop from crevices and rooftops. Despite their harmless nature, they pose indefinite harm, impacting human health. Improper handling and poor management measures contribute to numerous challenges.

People usually either manually shoo away insects around them or pick them up for removal. However, it's not well-known that many beetles, such as blister beetles and Mupli beetles, emit foul-smelling phenolics and other chemicals that can cause burns and rashes. Handling these beetles roughly can result in a squirt of secretions that irritate the handler’s skin.

Besides burns and breakouts, there have been scientifically confirmed instances of keratoconjunctivitis (inflammation of the eyes’ cornea and conjunctiva) in areas where these beetles invade. This phenomenon is particularly common in poor working-class thatched houses, where the beetles easily settle. The reason? Their strong attraction to dried leaves, which they voraciously feed on.

Coughs and other respiratory illnesses like breathing issues among affected inhabitants are common symptoms, possibly as an allergic response to stench accumulated via their congested assemblage. Unfortunately, civilians are being forcibly relocated due to a minor beetle infestation, causing them to leave their only place of comfort. Mupli beetles persistently occupy food, water, floors, walls, and animals. To date, no stringent control measures have been suggested.

The best method adopted to extinguish these insects is spraying of kerosene but since it’s volatile, it is ineffective once vapourised and offer no permanent solution. Practices like usage of plant essential oils and turning off lights inside houses are considered most effective. And if population density is high, mass killing by fire is opted.

In affected regions, people used aluminum sheets to deter Muplis from burrowing in. However, the effectiveness of these measures remains uncertain until proven otherwise.

The Mupli beetles have made it clear that precipitation as well as agricultural waste and by-product management play an essential role in mediating insect cycles, especially their reproductive success.

Human actions also disturb nature’s cycles contributing to insects’ massive surfacing.

India has been facing insect attacks in the past few decades, hampering agriculture and human health. There were reports of mealy bug surge (in Noida), desert locust attacks (in northwest and central India), coffee locust swarms in Wayanad, ear head cutting caterpillar attack on rice from Assam (where it is noted as prolonged dry conditions and delayed rains contributed to this pest attack), cycad scales savouring the sap and eventually destroying Queen Sago plants in Kerala, brown plant hopper attack in standing paddy crops of Kuttanad, Kerala, among others. Such incidents are indicative of how tremendously these gogga (insects) can impair food security as well as deteriorate agriculture and faltering income security of farmers.

The wood-boring Asian ambrosia beetle (Xylosandrus crassiusculus) can also cause significant damage. These insects bore into rubber fuel tubes ultimately leading to fuel leakage resulting abrupt fires. As per Kerala Forest Research Institute and their research team, variable climatic conditions with dwindling habitats and evolution to adapt to alternative food sources promotes sudden insect population upswings. 

The attack of the yellow crazy ants in Tamil Nadu is another example of how terrifying and dangerous insect invasions can be for human beings.

The ants sprayed formic acid while climbing on people and cattle in seven villages, causing skin burns. Yellow crazy ants are opportunistic feeders, willing to consume anything they can grasp.

Experts suggested that rising temperatures might have increased the ants’ metabolic rates, influencing their feeding habits. However, the exact cause of this event remains unclear.

Climate change can make such incidents more common if not addressed in time. How far can learning and educating communities regarding such matters be relevant amid climate crisis? All these questions are obligatory in the current scenario of biodiversity loss, habitat fragmentation, intensive agricultural methodologies, global warming and changing precipitation rates.

Ensuring safe settlements is crucial, along with improving agricultural practices, waste management and land use. But either way, it is imperative to acknowledge the realities of climate change laying foundation for insect attacks not entirely on food crops but also to our survival.

On the one hand, insects are considered an inconvenience, while on the other, some important species are going extinct in this fast warming planet. It is a paradox that a tiny, ignored being can intimidate human survival so deeply, leaving us with no choice but to choose sustainability and endorsing eco-friendly lifestyles.

Amritha Jaiprekash Kurup is an independent insect conservationist and researcher. Views expressed are the author’s own and don’t necessarily reflect those of Down To Earth.