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A Day-Long Battle Against the Insect Army at My Vertical Farm

Imamura here. There was a morning, right after Japan’s rainy season ended, when my usual position on insects from outside got a little shaken.

The Morning Everything Looked Gray

It was a morning right after the rainy season ended. In Japan, this is when the long weeks of rain give way — and insects emerge all at once.

The moment I stepped out of the car, the area around the facility looked different from usual. Normally you’d just see rice paddies and irrigation channels in the morning light. But that day, everything looked faintly gray and hazy. For a split second I thought: fog, maybe pollen?

It was neither.

What was drifting over the rice paddies and channels was a massive swarm of small insects — most resembling mosquitoes or midges, though hard to tell at that scale. The closer I got, the more I could see the fine dots moving in restless, shimmering waves across my field of vision. The sound of my car door closing rang out with strange clarity, and then the ambient sounds around me faded.

“Is all of this… insects?”

My general view is that insects from outside don’t become a major problem in vertical farms. I’ve written as much on this site, and in books I’ve written on vertical farming. Hygiene management is of course necessary — but I’ve always thought that outside insects rarely turn into a serious crisis on their own.

That morning’s scene, though, was the kind of scale that made me want to set my position aside.

The Gap at the Receiving Entrance

Uneasy, I went around to the back of the facility. At the receiving entrance facing the irrigation channel, there was a small gap. A spot I saw every single day — the kind of place where I’d always thought, “eh, this much is probably fine,” and moved on.

Insects were getting in through that gap.

Not one or two. A continuous stream of countless insects was flowing through the small opening without stopping. The floor and walls already had insects spreading across them, and some were drifting in the air. Even now as I write this, I can clearly picture the gray, restless movement that had formed at the base of that receiving entrance.

No other staff had arrived yet. I needed to stop the spread before it reached the growing area.

The first thing I thought of: adhesive sheets. If I set out enough, surely they’d hold the line. But the result came faster than expected. The sheets filled up with insects almost instantly — the adhesive surface saturated.

And then the next wave of insects walked right over the ones already stuck to it.

I’d built what I thought was a barrier. In practice, I’d created a paved path. It wasn’t funny — but the insects had broken through so effortlessly that I felt a flicker of involuntary admiration. No — admiring them was not the priority.

I checked the time: 8:30 a.m. Still morning, and I already felt like the day’s full exhaustion had settled onto my shoulders. Sticky sheets: useless. Need to stop them before they reach the growing area. Insects. Gap. Floor. Walls. The only option was to vacuum.

So I dragged the large shop vacuum out from the office.

Fighting Back with a Vacuum Cleaner

Pointing a vacuum cleaner nozzle at a swarm of insects — I imagine it looked pretty strange from the side. I was serious. More than serious: so intent that I had no spare attention for whether it looked strange.

When I switched on the vacuum, the insects on the floor, the ones clinging to the walls, and the ones drifting in the air were audibly sucked in. The roar of the vacuum stayed in my ears, and the vibration of the nozzle traveled into my hands. My hands kept slipping from sweat, so I had to re-grip over and over while I kept vacuuming.

It was clearly more effective than the sticky sheets. It still couldn’t stop everything — but I vacuumed up every intruder I could find, cleared the floor, cleared the walls, and then vacuumed up the new arrivals. And repeated that.

Partway through, other staff arrived, and we all dealt with it together. I’d never imagined that in a vertical farm, there would be a morning when a vacuum cleaner was the hero of the day.

After noon, the massive swarm outside gradually began to quiet down. The number of new arrivals slowly decreased. By evening, the intrusion had stopped completely.

This species apparently has a very short lifespan — the insects that emerged that morning had died out by evening. The insects that had been everywhere that morning were, by evening, gone as if they’d never been there.

Don’t Miss the Gap

That evening, we did a thorough cleaning of the entire facility as a team. We were tired — considerably — but the plants were safe. That part was a genuine relief.

My basic position that insects from outside don’t become a major problem at a vertical farm hasn’t changed. But being adjacent to the outdoor environment means there will be exceptions. Rice paddies, irrigation channels, the change of seasons, a mass emergence. When conditions align, a small gap that never mattered before can suddenly become a significant vulnerability.

On the way home, I thought briefly about the countless insects that had been sucked into the vacuum. There’s something hard to put into words about so many short lives ending inside a vacuum cleaner.

Ever since, I pay considerably more attention to any gaps leading into the facility than I used to. The places where you’ve thought “this much is probably fine” are exactly the ones worth checking again on a post-rainy-season morning, just to be sure. Insects don’t take our convenience into account.