Coco, I live in Massachusetts where it gets plenty cold in winter and the flies seem to reproduce from year to year just fine.

poor Nikki, you have my deepest sympathy!8-|

Ptrick - your memory is playing tricks on you this time. The Great Ladybird Invasion coincided with that iconic summer of '76 - 29 years ago! I well recall this since, as a child, I was being frogmarched along the South Downs Way, en famille, on a Youth Hosteling holiday.
Scorching heat, a plague of ladybirds and 15 miles to go (still) seem to be my abiding memories of that summer.

Dr D.