Are bugs really disappearing?

Vox reader Gunnar Colleen writes: “So are all the bugs really disappearing? If so, why does it seem like nobody is doing anything about it? Is there anything I can personally do to help out the little guys at the very base of our ecosystems? I’ve been thinking about this a lot and it seems like something that is really important.”

Many of the bugs that humans encounter — the mosquitoes and houseflies, cockroaches and bed bugs — are, in a word, disgusting.

But these loathsome pests represent an almost unimaginably small fraction of the planet’s insect diversity. Scientists have discovered about one million species so far, and they estimate there are likely several million more that they have yet to describe.

This incredible diversity of bug life sustains our planet. Insects pollinate our favorite foods, clean up our messes, and even help reduce the number of insects that we don’t like. Dragonflies, for example, eat mosquitoes, and certain wasps prey on cockroaches.

That’s why recent headlines warning of an “insect apocalypse” — the idea that a huge number of insects are disappearing — are so alarming. A world without insects is not one we want to live in.

But are bugs actually disappearing? It’s a good question, considering there’s an ongoing debate over the true extent of insect loss.

For help answering this question, I spoke with someone who knows insects better than almost anyone: Scott Hoffman Black, executive director of the Xerces Society for Invertebrate Conservation, a nonprofit that works to protect insects. He’s been with the group for more than two decades.

“Unfortunately, the data is conclusive,” Black told me. “Insects on the whole are now declining. And it’s very worrisome.”

Understanding the scale of this decline is a bit more complicated. Many groups of insects, like flies, haven’t been thoroughly studied, so there are still a lot of unknowns. Some critters, meanwhile, are thriving in the world humans have created. Disease-carrying mosquitoes, for example, are expanding into new areas as the climate warms.

But on the whole, studied populations of insects are declining by about 1 percent to 2 percent each year, according to the best available research, Black said. When compounded over two decades, that amounts to as much as a 30 percent decline in insect populations.

“I don’t know any insect ecologist that doesn’t agree that insects are now declining,” Black said. “This was a question 10 years ago. It’s not really a question now.”

That would be us, humans.

The first problem, Black says, is that we’re gobbling up insect habitat, like prairies and forests, with our farms, buildings, and homes. He points out that there are some 40 million acres of lawn in the US (bluegrass, mostly), which has replaced native habitat.

“Very few animals, insects included,” can live off of bluegrass, Black said. “It’s a giant monoculture.”

The extremely common practice of spraying insecticides only makes the landscape less habitable. Globally, we now use more pesticides than at any point in human history, Black said, and they’re clearly linked to insect declines. One recent study, for example, linked insecticides — and particularly neonicotinoids — to the decline of butterflies in the Midwest.

Then you add in climate change and its many symptoms — from rising temperatures and deepening droughts to more extreme rainfall and hurricanes — which together can amplify these downward trends.

“That affects us, but it also affects all of the animals,” Black said.

Arthropods, a group that includes insects, spiders, and crustaceans, make up roughly half of all animals on Earth, by biomass. There are, for example, an estimated 20 quadrillion ants. And because insects are superabundant and everywhere — in streams and lakes, deserts and mountaintops — they are essential parts to every ecosystem.

Scientists estimate that about 90 percent of flowering plants are pollinated by animals, most of which are insects. More than a third of our food crops depend on pollinators, including almonds, chocolate, and coffee.

Insects also make up a huge part of the diet of many animals. Nearly all terrestrial birds in North America feed their young invertebrates. “If you like birds, you should thank an insect,” Black said.

Many fish eat insects, too, including salmon, he said. “They would not make it to the ocean without feeding on insects,” Black said. “This goes all the way up the food chain. Think of grizzly bears. They eat salmon, which rely on insects. And their other main food source is berries, which are insect-pollinated. So bears almost exclusively eat a diet that comes from insects.”

Also worth mentioning: Insects, like dung beetles, clean up animal feces that might otherwise smother the ground and fill the air with a foul stench.

Saving insects isn’t an issue that can be solved by one person alone. City, state, and federal governments play a major role in helping insects, such as by passing legislation to limit habitat loss or certain insecticide chemicals. But there’s still a lot that individuals can do, Black said.

Black pointed me to a publication he co-authored titled, “Eight simple actions that individuals can take to save insects from global declines.” It suggests, among other things, creating insect habitat by growing more native plants. That could entail ripping up part of your lawn, even just 10 percent, or putting a few plants out on your city balcony.

“We have a member in Germany who has a big garden space on his balcony, and he’s getting like a dozen of different bee species,” Black said. “You don’t need to rip out your whole lawn and go native unless you want to. Just start.”

Here are some other tips Black shared:

Relative to other major issues that face our planet and our communities — war, American politics, life-threatening natural disasters — insect declines have not, rather unsurprisingly, drawn much attention. They’re harder to see.

But what’s heartening, Black said, is that in his nearly 25 years of work at Xerces he’s seen support for insects swell dramatically. “There are tens of millions of people across the world who now garden for pollinators,” he told me. “There’s a growing movement.”

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