I think the easiest method of controlling insects is to use a soap and water solution. Use a soap and not a detergent, Palmolive is a soap vs Dawn which is a detergent. Just a small amount of soap, say 1/2 a tsp in a spray bottle is good enough. Spray all leaf surfaces and repeat in two or three days to get any newly hatched critters.
Using an oil is more dangerous for plant health because you can burn the leaves in hot weather or bright light. It's best to spray anything is shady conditions but you will have far less problems if you skip the oil. Products like Neem oil work well and they shine the leaves up but they also can cause burns if conditions are too bright. Neem oil also had insecticidal properties vs regular oils which smother insects.

Mike

Mike how about using non mint mouthwash? ~ Mary