Here are some sources that help to explain what is happening, and implications of these occurrences:
Human society under urgent threat from loss of Earth's natural life
https://www.theguardian.com/environment/2019/may/06/human-society-under-urgent-threat-loss-earth-natural-life-un-reportAs Insect Populations Decline, Scientists Are Trying to Understand Why
https://www.scientificamerican.com/article/as-insect-populations-decline-scientists-are-trying-to-understand-why/?redirect=1
Insect and bird populations declining dramatically in Germany
https://www.dw.com/en/insect-and-bird-populations-declining-dramatically-in-germany/a-41030897
Why insect populations are plummeting—and why it matters
https://www.nationalgeographic.com/animals/2019/02/why-insect-populations-are-plummeting-and-why-it-matters/
Could Loss Of Flying Insects Be Leading To Loss Of Birds?
https://www.wxpr.org/post/could-loss-flying-insects-leading-loss-birds#stream/0