It’s Raining Moths – What’s Causing The Great Delhi Insect Menace

The Svetambara is one of the two main sects of Jainism, followers of which in believe total non-violence. They always clad themselves in white clothes and some even cover their mouths with a white cloth to practise ahimsa even when they talk. By doing so they minimize the possibility of inhaling small organisms.

So unless you’re a monk who practices Svetambara it is quite certain that you must have inhaled or eaten quite a few insects that have suddenly bombarded the night skies of Delhi in the past few weeks. It has become a common sight over the past few weeks to see thousands of insects swarm around even the smallest sources of light, much to the amazement of delhites who are wondering about the reasons of this moth onslaught. So the basic questions that arise are: What are these insects ? Where are they coming from ? Why are they coming here and When does this menace stop ?

These insects are an immigrant pest called the Brown Plant Hopper(also known as leafhoppers with local names like phudka or bhusaddi) and they are coming from the rice fields of neighbouring Haryana. G.T. Gujar, head of the Division of Entomology at the Indian Agricultural Research Institute, says the population of this pest has increased “300 to 400 times this year“. A single rice plant could have more than a thousand of these insects hidden inside, he says. “It used to be an agricultural menace in the 1990s but was controlled by pesticides“, says TP Rajendran, Assistant Director General for Plant Protection at the Indian Council of Agricultural Research.

This year, untimely rains began a chain reaction that led the Hopper population to explode. The rains caused an increase in the population of crop pests, which made farmers use increasing amounts of insecticides like carbaryl, which ended up killing off all the natural predators of the Hopper like spiders and frogs. The Hopper, meanwhile, turned mutant and developed immunity to the available pesticides. It then went forth and multiplied. Normally, the insects would be drawn towards the moonlight and they would fly in huge swarms for mating. In the city, however, they get drawn to electric lights and usually die due to the intense heat. “There is no way to keep them out of homes. They are extremely small and can fly in through the smallest of cracks. Since they don’t cause any harm, nobody really bothers. But this time, due to their unusually large number, people are facing problems,” says Dr Mohammad Faisal, an entomologist.

The female insect lays eggs in the mud. Then, the eggs can lie dormant for good 6-8 months and hatch when humidity increases. When the temperature ranges between 35 and 22 degrees Celsius and relative humidity is about 85%, the eggs can hatch even in four days. One female leafhopper can lay up to 681 eggs during its lifetime. The leafhoppers we see are adults, with a life span of 23-39 days.

The Menace is expected to end most likely after Diwali once it starts to get a little cold.