Climate change and habitat loss from big agriculture are working together to suffocate global insect populations, according to a new study, with each problem exacerbating the other.

Insects, which include beautiful butterflies and fireflies, are important pollinators of plants that feed people and help to make soil more fertile. Scientists have noticed a dramatic drop in both total bug numbers and insect species diversity, describing it as a “death by 1,000 cuts.” Pesticides and light pollution are among the areas where cuts are being made.

Big single-crop agriculture, which leaves less habitat and leafy food for bugs, and rising temperatures from climate change are both huge problems for insects, according to a new study published in the journal Nature Wednesday based on more than 750,000 samples from 18,000 different species of insects. It’s the interaction of habitat loss and climate change that decimates bug populations.

Climate change and habitat loss from agriculture were found to be magnifying each other in about half of the cases where insect numbers had plummeted. The same dynamic was at work in more than a quarter of the cases of biodiversity loss, which means fewer species.

“We know insects are under threat. We’re now getting a much bigger handle on what they are threatened by and how much,” said study author Charlotte Outhwaite, an ecologist at the University College of London.

“In this case, the habitat loss and climate change can often be worse than if they were acting on their own, as one can make the impact of the other worse and vice versa,” Outhwaite said. “We’re missing part of the picture if we are only looking at these things individually.”

Monoculture agriculture, for example, reduces tree shading, making a given location hotter. Climate change is on top of that, she added. Insects that need to escape the heat or migrate north to cooler climates may encounter problems due to a lack of suitable habitat provided by large farms.

Outhwaite says it’s particularly a problem in countries like Indonesia and Brazil, where forests are being cleared and temperatures are rising faster than in other parts of the world.

That’s difficult for insects like the vexing midge.

“Midges are the primary pollinators of cocoa, and people dislike midges.” They’re the annoyances that bite you and bother you at picnics,” Outhwaite explained. “But if you like chocolate you should be appreciative because without them we would have a lot less cocoa.”

The same can be said for bees, which are struggling due to climate change and single-crop farming, according to Outhwaite.

According to the United States Department of Agriculture, insect pollinators are responsible for about one-third of the human diet. According to a 2016 United Nations science report, two out of every five species of invertebrate pollinators, such as bees and butterflies, are on the verge of extinction.

This study is significant because it is the first to link climate change and industrialized agriculture in explaining insect harm, according to University of Connecticut entomologist David Wagner, who was not involved in the research. Because the study used so many different samples and species and looked around the world, that gives its findings more credibility, Wagner said.