You can get rid of a boat load of aphids and spider mites by the careful spraying of plain water to blast them away. Not so strong that you could cause plant damage, but enough to get rid of the critters. Spider mites tend to congregate on the underside of foliage, so pay some attention to that location. Use your fingers, too, to help squish. Then, you might try an application of insecticidal soap, mixed according to label directions. Again, direct the spray to all parts of the plant. I've found that spider mites can be controlled by applications of alcohol and water (in a 1:4 ratio). Save that remedy for when you bring your plant inside or out of the direct sunlight. Same goes for the soap, too. I should say that spider mites can be very difficult to get rid of entirely. Aphids, not so much. But you will have to do a much better job at observing your plant from now on, so that you can continue treatments. Pest populations like that don't occur overnight.

Rhizo...Boy do we owe each other a letter!! MY mother has been asking about you for days and if you still had slippy's? I've missed you.. That's good for Mrshigsy..lol I was beginning to woner..lol So happy to see you Rhizo)

Yes you should. Your lemon will be a nice pretty foliage tree but if you want fruit you will probably never get it. Harris in flordia and Briteleaf in flordia have dwarf and full size so be sure it's a dwarf your buying. four winds only has dwarf but their rootstock is slightly less desirable. They do have very fancy tags that I really like. Most of mine are from four winds. If you do get another lemon consider the Mediterranean ones also. I wish I would have got a Santa Teresa instead of a Lisbon. But it was one of 4 in my first order.

Christina, those other leaves look mighty fine and dark green. You must of been doing something right all year. Many times citrus will drop leaves, turn color or even get attacked by pests this time of the year. The cold comes into play. A lot less direct over head sunlight like summer and watering has to be pulled back dependent on the temps.. That leaf looks like it just naturally fell off.....Mike When you sprayed with Neem, did you spray under the leaves too? Looks like you did the tops but not the bottom..