Is the insect apocalypse really upon us? It's complicated, say researchers

Contrary to the trend for land-dwelling insects, the number of freshwater insects has increased. This could be due to effective water protection measures. The photo shows common water striders (Gerris lacustris) while mating.

(CNN)Bumble bees are struggling. Fireflies are no longer lighting up the night, and fewer butterflies are fluttering over fields.

Several recent reports have warned of a crushing decline in insect populations that could have a catastrophic effect on our environment and food supply.
However, a new study that's been described as the largest and most comprehensive assessment to date of insect and arachnid populations paints a much more nuanced picture. It suggested that while some might be in peril, an insect apocalypse isn't upon us quite yet.
    At the same time, researchers said the study is by no means complete, and there is an urgent need to ramp up the study of insect populations to gather more data.
      While insects that live on land are declining at 9% per decade (0.92% a year), which is a much smaller percentage than suggested by other studies, the study found that there's been an increase of freshwater insects, like midges and mayflies, of 11% per decade. That could be as a result of efforts to clean up the water supply.
      "Insect populations are like logs of wood that are pushed under water. They want to come up, while we keep pushing them further down. But we can reduce the pressure so they can rise again," said Roel van Klink, a researcher at the German Centre for Integrative Biodiversity Research (iDiv) and Leipzig University.
      "The freshwater insects have shown us this is possible. It's just not always easy to identify the causes of declines, and thus the most effective measures to reverse them. And these may also differ between locations."
        The study, which published in the journal Science on Thursday, looked at 166 long-term surveys conducted across 1,676 sites worldwide.
        Trends were highly variable, with differences not only between regions but also areas of study that were close together.
        The colored dots represent the location and strength of decline or increase of insect population in the 166 data sets used in the study. Credit Van Klink et al, Science [2020]

        'Critically understudied'

        One of the first studies to signal the doom -- spurring reports of insect Armageddon -- came in 2017 when data from nature reserves in western Germany suggested that flying insects had declined by 75% over 27 years.
        A review published in 2019 indicated that 40% of insect species could become extinct in the next few decades, with insect biomass projected to decline by a staggering 2.5% a year. That figure was quoted in other reports on the topic.
        Some insects perform important functions in our ecosystems, such as pollination of wild and cultivated plants. The photo shows the European orchard bee (Osmia cornuta).
        One of the reasons studying insect populations is so difficult is that there are more of them than any other type of animal on the planet -- there's said to be more ladybug species