Adults are dieing at alarming rates. What scientists found during autopsies were high concentrations of an insecticide called Myrex. Simple problem really. Not so simple. The problem is, 'designer' insecticides are more robust than spontaneous molecular experiments by nature.
Nature tries things slowly, in small local trials and quantities.
What fails, gets washed away in the ocean of alternatives that succeed and blend in. What succeeds, gains footholds, and becomes more prominent by continued integrations. Human techniques throw massive quantities of substances into the world and reaps no in-between. Successes are extraordinary. Problems tend to become disasters.