The Relationship Between Insect Abundance and Seasonal Temperature and Weather Trends

Global climate change is affecting seasonal temperature and weather patterns. There is concern that these changes may be leading to declines in insect populations. One hypothesis proposes that the increase of extreme weather events such as extreme precipitation events is leading to declines of insects. Another possible cause could be an increase in wind speeds, which can decrease the capture rate of insect samplers. We used data from the UW-Milwaukee Field Station in Saukville, WI from 2000-2020, to analyze long-term patterns of weather and insect biomass. Insects were trapped using two different methods, a malaise trap and suction trap. The malaise trap is a tent-like structure that funnels aerial insects into a bottle of alcohol, while the suction trap uses an electric fan to “pull” aerial insects into a bottle of alcohol. The collected insects were then sorted by order, dried for one hour, and weighed with an electric balance. Weather data were also collected daily, including temperature, precipitation, and wind speed. We predicted that rainy days, higher wind speeds, and colder temperature events would lead to a drop in insect biomass over the long-term. We also predicted that this would have a noticeable effect on peak insect biomass, which would be lower in more recent years than in the past. We found that insect biomass decreased when there was more rain or higher wind speeds. Insect biomass was also lower when soil temperature was lower. However, there was not a significant change in peak biomass over the past twenty years, showing that insect biomass at the UW-Milwaukee Field Station has been relatively stable, despite short-term variation due to local weather