So I'm growing a pink laugh-o-dil and it's plagued by bugs. I've been able to get rid of bugs of other levels, but for some reason these won't budge. I tried logging off multiple times, using treasure cards as well as the regular pest spells for level four a few times and nothing has worked. Interestingly, I have no problems with other gardening spells on this plant or on any of the others.
You need to use a spell that can kill rank four bugs or higher such as Pest Bomb or Fly Swatter. You can also use Ant Lion to kill any rank bugs. I'd recommend Ant Lion if that doesn't work, then dig up the seeds and try again.