I have this same view in my yard... orange bucket with tomato plants!

Are the critters hurting anything? Most critters are harmless and some are even beneficial!

A gallon of water and a few spoons of regular dish washing soap mixed and sprayed through an atomizer (spray bottle) will do the trick. It suffocates the critters and shouldn't bother the plant. I usually rinse it off after a few minutes, but sometimes I don't and there have been no apparent issues.