What's been lost... Entomologists from Krefeld, Germany, collected flying insects for two weeks in August 1994 (left) and—at the same site, with an identical trap— in August 2016 (right). Similar data from 63 German protected areas overall gave a shocking result: a 76 percent drop in insect biomass between 1989 and 2016. It has worsened significantly in the past 9 years. Photographed at Entomological Society of Krefeld
@VeroniqueB99 maybe the trap from 1989 caught all the insects
Seriously though, I can think of many causes for this but I'll share one that has not yet been mentioned here, artificial light. There's so much of it and flying insects b-line for it whenever they see it, that *has* to mess with their life cycle over time.
@VeroniqueB99 “for two hours each evening, the site got power and a 25-watt bulb flickered on above the porch. Out of the forest darkness, a tornado of #insects would flock to its glow, spinning and dancing before the light. Lit up, the side of the house would be “absolutely plastered with moths – tens of thousands of them”, #DanielJanzen says. [The walls would be] absolutely plastered with moths – tens of thousands of them… Inspired, he decided to erect a sheet for a light trap with a camera – a common way to document flying insect numbers and diversity. In that first photograph, taken in 1978, the lit-up sheet is so thickly studded with moths that in places the fabric is barely visible, transformed into what looks like densely patterned, crawling wallpaper.
Scientists identified an astonishing 3,000 species from that light trap, and the trajectory of Janzen’s career was transformed, from the study of seeds to a lifetime specialising in the forest’s barely documented populations of caterpillars and moths.
Now 86, Janzen still works in the same research hut in the #Guanacaste (Costa Rica) conservation area, alongside his longtime collaborator, spouse and fellow ecologist, #WinnieHallwachs. But in the forest that surrounds them, something has changed. Trees that once crawled with insects lie uncannily still.”