Worms disappeared now that Weather is normal

No more earthworms show up on the PCN once the haze cleared.  It is quite interesting phenomenon.  No dead or live earthworms on the track.  So I have no idea why they come up to "commit suicide" as many died on the tracks unless they were collected by me before drying out or run over by cyclists.  I checked on the internet.  Earthworms do come up during rain.  Nothing on why earthworms come up during haze.  This must be a phenomenon not observed before.