Mutant seedlings - any way to know...

Is there any way to know how many are left bouncing around your town?

Some of my neighbors are far enough ahead that they're already dropping them (thank you all, by the way - it's pushed me ahead of where I would be. Special thanks to Steve____ who just dropped 7 in my town.), and I know that hearing the splorch sound when you enter town tells you there are some there, but is there any indication to tell you that you've gotten them all? They move so quickly they could be off screen before I can move to the part of town where they are. And so far they don't seem to be attracted to streets or houses like some past invaders (aliens, Feds).