Not sure, but bug/critter populations do seem to be cylical-for instance this year the crickets seemed extra thick around here. One year husband trapped 19 skunks around here (never that many before or since).
The last couple years we have not had nearly as many of the Asian beetles either (colored like a traditional ladybug; but larger, rounder and stink if you touch them or squish them...and they do pinch you). About 10 years ago we were literally invaded by them after scientists set millions (or billions) of them loose in WI due to soybean aphids. Never cured the aphid problem...now the beetles are migrating all over the country. The way those things crawl into walls, I'm sure the walls of our house and shop are now equally as full of beetles as they are of blown-in insulation.