Insect Collapse; Ecologists Horrified.
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Chapter 42
Insect Collapse
Guanacaste, Costa Rica
June 10, 2025
The night air was replete with the sounds of the jungle as Ericka sat on the porch of a modest research hut at the Guanacaste field Station.
E. “So tell me Dr. Janzen how did you first start researching Costa Rican insect life?
D. “First of all, call me Dan, and this is my research partner and wife Winnie Hallwachs.”
E. “Thank you both for putting me up … and putting up with me!”
D. “Not at all, not at all. Happy to have you. Well, you see it all started in the rocking chair you are sitting in.”
E. “How was that?”
D. “I was a callow, young, wet-behind-the-ears researcher studying plants when I slipped and fell down a steep vine covered ravine.”
E. “Oh my God!”
D. “Yes, I landed on my back and the telephoto lens of my camera snapped three ribs and pushed them up into my thorax.”
E. “What did you do? How did you get help?”
D. “I had to crawl two miles to get back to this same research hut. I had no neighbors, there were no decent roads and no simple way to get to the hospital.”
E. “So, what did you do?”
D. “I used a bedsheet to strap myself into the same chair you are sitting in, and sat for a month waiting for my bones to heal.”
W. “And he started to watch.”
D. “Yes, I started to watch and realize I was sitting in the midst of this seething world of life. Every branch of every tree seemed to host its own metropolis of creatures hunting, flying, crawling, munching on leaves and depositing thick layers of droppings.”
W. “Yes you could hear the sounds of the frass falling on the jungle floor.”
E. “What’s frass?”
D. “That’s our fancy way of saying bug shit.”
E. “Thought so!”
W. “But, the real show would start at dusk. That was when our research hut got about four hours of power so a 25-watt bulb flickered over the porch. A tornado of insects would flock out of the jungle and dance and spin in its faint glow.”
D. “The side of our hut would be absolutely plastered with moths, tens of thousands of them. So, I decided to use a sheet and a camera to document them.”
W. “In that first photo taken in 1978 the lit-up sheet was so thickly studded with moths that the fabric was barely visible. It looked crawling wallpaper.”
D. “My colleagues and I identified an amazing 3,000 species of moths on that sheet and the trajectory of my career changed from the study of seeds to documenting the populations of caterpillars and moths.”
W. “So now we both work in the same research hut and Dan is 86 years, but the forest that surrounds us is uncannily quiet. The hum of wild bees has faded, the leaves that should be chewed, hang whole and un-nibbled.”
D. “Yes, it is those glossy, untouched leaves that spook us the most. It is as if we are living in a pristine greenhouse rather than a living ecosystem. Not a forest but a museum.”
W. “Today when we repeat the experiment using the same sheets, the same light, in the same place, during the same time of the year, and during the same time in the lunar cycle, there are simply no moths on that sheet.”
D. “What is most distressing is that this is in a protected area. As far as we know it is far away from any insecticide and pesticide use, yet even here the insect numbers are plummeting and nobody know why.”
E. “Yes, I’ve talked to truckers who say they don’t see the numbers of squashed bugs on their windshields as they used to see decades before.”
D. “I suppose one could call that the window-shield data set.”
W. “But what we do see here is that the populations of insect feeding birds, lizards, frogs, and bats have cratered.”
E. So what is causing this destruction?”
D. “We think we are starting to see the culprit emerging from the data.”
E. And it is?”
W. “Global warming. You see a tropical forest ecosystem is like a Swiss watch. Each element is finely tuned and interlocks with the other elements; the heat, the humidity, the rainfall, the unfolding leaves the length of the seasons and the start and stop of the lifecycles of the plants and animals and the predators that feed on them.
Animals like insects, birds, lizards and frogs have precisely evolved their migrations and breeding times to small signals; like a change in humidity, a lengthening of daylight or a small rise or fall in temperature.”
D. “When I arrived here in 1963 the dry season lasted four months. Today it lasts six months. Insects that used to spend four months underground waiting for the rainy season, now have to survive an additional two months of hot dry desiccating weather. Many are not succeeding.”
W. “The killer, that is pulling the trigger on all the plants and animals being out of synch is actually water. Insects are all surface area. They can’t hold water. Even a brief drought lasting just a few days can wipe out millions of humidity-dependent insects.
D. “So we are in a new inflection point in history. Up until the past decade the major driver of biodiversity losses around the planet were really land degradation and habitat loss. But now climate change has exceeded that, by far, driving the decline of 91 percent of all the imperilled species.”
W. “We know quite a number of entomologists are starting to look away. One of our very good friends no longer has the emotional courage to hang up a sheet to collect moths. It is too devastating to see how few there are.”
E. “That is just so tragic, when I talk to people studying plankton, fish, plants, frogs, lizards, birds, and larger more charismatic species they are all depressed and frustrated. They see that our ecosystem is unravelling right before our eyes, but they can’t convince anyone to really do anything significant about it.”