I deal with spider mites on my Norfolk island pine indoors every year. I spray it with 90% rubbing alcohol to kill them followed by washing it off with water. Low humidity and lack of air circulation allows spider mites too thrive. Wash the banana leaves with water daily and spray as needed.

Keeping the humidity up is really important. I would was it really thoroughly and clean the trunk and leaves with a paper towel and water. If its somewhat older, I would cut all the leaves off except the growing one. Then put it in the ground in a sunny spot with some occasional fertilizer and watch it take off!
Good luck!
-Alex

Thank you for the advice !

Is this plant outside???
If so,you should be able to hose it of a few times a week and dislodge the little critters.