75% decline over 27 years in total flying insect biomass in protected areas
This study appears to be an alarmist rehash of what was  previously discussed on HN:  <a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=14323533" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=14323533</a><p>Here&#x27;s one of the original papers:
<a href="https:&#x2F;&#x2F;www.farmlandbirds.net&#x2F;sites&#x2F;default&#x2F;files&#x2F;Orbrioch Nature reserve.pdf" rel="nofollow">https:&#x2F;&#x2F;www.farmlandbirds.net&#x2F;sites&#x2F;default&#x2F;files&#x2F;Orbrioch%2...</a><p>The 75% decline number appears to be from two data points from a 220-acre plot. From that paper:<p><i>&quot;What follows is a description of measured Insect-Biomasses from samples collected in the Orbroich Bruch Nature Reserve, near Krefeld, using Malaise Insect Traps. The results show that, in the same two areas, sampled in the years 1989 and 2013, there was a dramatic fall in the number of flying insects. Using the same traps, in the same areas, significant reductions of insect populations, of more than 75%, were found. Our data confirms, that in the areas studied, less than 25% of the original number of flying insects collected in 1989, were still present in 2013.&quot;</i><p><i>&quot;The Orboicher Bruch, to the Northwest of Krefeld, is a designated Nature Reserve of around 100 hectares (220 acres). Due to the reserve’s relatively remote location and its rugged landscape, intensive farming came to the area only recently.&quot;</i><p>So alarmists are extrapolating from two data points (years 1989 and 2013) for a 220-hectare plot of German farmland to the entire world. I think that is a bit of a stretch, even for statistics.<p>since different bugs breed in different seasons, and numbers depend on the fruitfulness of previous generations, food supply, predation, disease, temperature and so on, this bug weight could vary considerably from year to year (or site to site) for any number of reasons.  While one year cicadas thrive, the next year there may be none. Shocking, simply shocking!<p>BTW they&#x27;re measuring the <i>weight</i> of dead bugs - not how many bugs or what species of bugs - just the weight of bugs. Actually they&#x27;re not  even measuring that, they&#x27;re measuring the weight of dead bugs&#x27; soaked in 70-80% alcohol.<p>I could go on and on about controls in statistical experiments but I think you get the idea.<p>See the original HN posting for discussions pointers to the earlier papers.