• Posted April 26, 2025

Where Have All The Insects Gone — And Why?

SATURDAY, April 26, 2025 (HealthDay News) — From beetles to moths, leafhoppers and butterflies, the world's insects are vanishing at a breakneck pace.

Since 2017, when European researchers reported that insect populations had declined 75% in fewer than 30 years, scientists have churned out study after study trying to parse out exactly why.

To get a handle on all those studies, a team from Binghamton University in upstate New York has published one more. It's a comprehensive analysis of more than 175 studies containing more than 500 hypotheses about the causes of insect decline. 

The No. 1 cause, not surprisingly, is agriculture, specifically insecticides and changing use of the land. 

But the analysis also shed light on a surprising culprit: favoritism.

Simply put: Scientists tend to focus on what this study describes as "charismatic" insects like bees and butterflies — even though they're actually minorities among insects. Others suffer as a result.

"It's really hard to talk about what everyone thinks, and so instead of getting 600 people into a room, we decided to take an approach where we read every paper that's either a review or a meta-analysis," said lead author Christopher Halsch, a post-doctoral researcher at Binghamton University in New York state. "The idea was to read them and extract what people say are 'causal pathways'."

Their research — published April 22 in BioScience — points to other threats that are often overlooked. 

Among them, for instance, are extreme rain, catastrophic fire and Earth's rising temperature. And, Halsch's team says, these factors are intertwined and too often ignored.

"None of the papers mentioned natural disasters," said Eliza Grames, assistant professor of biological sciences at Binghamton University. "No papers looked at human intrusions and disturbance, or the effects of war on insects, or railroads."

So, she continued, big threats to biodiversity go unexamined.

"The insect decline literature is really just focused on a few big stressors, as opposed to getting into the more specific ones, which are a lot more mechanistic," Grames said.

The review pointed up biases in the literature, especially a focus on what researchers described as "popular" bugs.

"Because people have focused so much on pollinators like bees and butterflies, we are limited in identifying conservation actions that benefit other insects," Grames said. 

Halsch noted that people care about bees because they're agriculturally important.

"So," he said, "there is a lot of research priority towards funding research on bees. … If you prioritize research on bees, you learn more about bees."

The upshot of their work is an interconnected network of 3,000 possible links, touching everything from beekeeping to urban sprawl.

The takeaway is this, Halsch said: "If we focus too much on bees and butterflies and their conservation, we will miss a lot of other species, most of them in fact."

More information

There's more about declining insect populations at the Florida Museum of Natural History.

SOURCE: Binghamton University, news release, April 17, 2025