When insects attack (should make a good TV show) ..... ..... plants mount a number of genetically encoded responses to the wounding, ALL of which require energy allocation. In plant cells, there are genes that control proteins functioning in defense, sending defense signals, altering metabolism, controlling cellular maintenance, and regulating photosynthesis, as well as many genes of unknown function. In short, plant energy reallocation is prioritized in the plant's own defense, & other things, like every day metabolism and photosynthesis are put on the back burner. When wounding occurs (insect attack) there is a "wound response" that occurs both at the site of injury as well as distally (in other plant parts). Plants can even differentiate between the wounds of a pin and those of insects and react in different fashion to the "attack". Without getting more technical, the plant produces various anti-feedants, anti-metabolites, and toxins that make the insects feel pretty unwelcome - as long as the plant is in good vitality, which means growing strongly, or has high energy reserves. In other words, as long as the plant is in good health. Stressed or strained plants cannot quickly or efficiently respond and ward off insect attack. The speed with which the response occurs, and the effectiveness of the defense response are also both energy driven, so it should be no surprise that plants grown indoors under constant stress are highly susceptible to insect marauders. If you want to keep the bugs away - your first line of defense should not be to reach for a systemic poison, but to keep your plants growing with as much vitality as possible, which is a cultural - not a chemical thing. ;o) Al

Just keep eye on the healthy leaves. If other leaves stay healthy in 2 or 3 days, then nothing to worry. If the symptoms spread further, maybe soil nutrients deficiency is the cause. No need to cut off any leaves since they still able to do photosynthesis, but if you think remove unhealthy leaves will make you feel better, then go ahead. Seems that you have enough healthy leaves to support plant growth.

Leaves are the plant's power source, and they're not diseased, so removing them just weakens the plant's ability to replace roots that have died due to overwatering. Roots need air for oxygen, so monitor the soil moisture at the bottom of the pot with the dowel test and only water when it comes out dry to the touch. Here's a post by Al from this thread. I guarantee that following this advice will take care of your watering issues and stop any more brown areas. Read the whole thread to really understand what's going on. "The calendar isn't what determines an appropriate watering interval; and you, not the guys at the store where you bought the plant, are in the best position to determine when your plant does or doesn't need watering. When the skewer first comes out dry or almost dry is the appropriate time to water. There ARE some things you can do that will shorten the intervals between necessary waterings, which would mean the plant has a greater fraction of unsaturated soil for a higher % of time, which is decidedly a plus. Follow this link to info on how to deal with water-retentive soils."

Browning is due to overwatering and/or a build up from fertilizers and tap water. The build ups are from you watering a cup per week and not flushing out the soil. When you water, you need to water thoroughly until it comes out the drain holes and discard the collected water. But for this plant, you need to put it in The tub and water 10x the amount it takes to start draining. Don’t do this until it’s time to water. Letting water sit doesn’t do much of anything. Flouride doesnt evaporate anyway. You we also likely overwateringif you were watering on a set schedule without knowing what’s going on with the soil deep in the pot. Use a sharpened wooden dowel and stick it in the pot all the way to the bottom and pull it out and inspect. Dark, damp with soil clung to it, don’t water. Clean and dry, water. Check with the dowel every couple days.