Hey there JP! I've experienced spidermites before so I always say it pays to be worries about spider mites. I don't know if Marigolds attract spidermites but what I do know is they're an absolute disaster to get rid of. In my experience if they're there they're there and no amount of companion plants will really Change that ... But if you're looking for anti pest plants check out : coriander, Dill, lavender , sunflower or lemon balm. Hope this helps ! 🚀