Possibly a factor. I think it's quite likely insect numbers are declining but so...

BaronMingus on Feb 25, 2019 | parent | context | favorite | on: Major survey finds worms are rare or absent in 20%...

Possibly a factor. I think it's quite likely insect numbers are declining but some amout of the windscreen affect could be accounted for by good old Darwin - all those insects you scraped off your windscreen found their reproductive success curtailed with extreme prejudice.