The number of flying insects has declined more than 75 percent over the last 25 years, according to a new study.
The data, gathered by scientists from the Krefeld Entomological Society in nature reserves across Germany, was published in the scientific journal Plos One.
Scientists are worried by the new findings because insects are important pollinators and a key part of the food chain, as they serve as prey for birds and other insects.
If you are an insect-eating bird in the area, “four-fifths of your food is gone in the last quarter-century, which is staggering,” said Dave Goulson, an ecologist at the University of Sussex and participating researcher in the study.
The decline of butterflies and bees over the years was already known by scientists. However, this is the first time the total loss of all flying insects was documented.
Changes in weather, landscapes, and plant coverage don’t explain the loss say the researchers. But increased agriculture and use of pesticides may be playing a role, although data on pesticide levels has not yet been collected.
In order to carry out the study, researchers laid out special traps called malaise traps to capture more than 1,500 samples of flying insects in 63 different natures reserves, then documented the changes over time.
Over the past 27 years, they found an average decline of 76 percent and an even higher decline over summer (82 percent).
Casper Hallman, another scientist on the team, highlighted how worrisome the problem was, given that the data had been taken from protected areas.
“All these areas are protected and most of them are managed natures reserves. Yet, this dramatic decline has occurred.”
Scientists agreed that more research is needed to discern the causes of this decline. But in the meantime, “we need to do less of the things that we know have a negative impact, such as the use of pesticides and the disappearance of farmland borders full of flowers,” said Dutch researcher Hans de Kroon.