I purchased a Campbell Valencia Orange tree from my local nursery around October or November and per the nursery worker's instructions, kept the tree inside in a sunny location all winter. I noticed that a couple of months ago the few fruits on it had gone from green to pale yellow and there were bright reddish/orange dots on the backside of the leaves, and in stringy webs hanging down. I identified these to be spider mites, so I put the tree out in the rain on a warmish day and then tried to wipe all the leaves off with a paper towel. I brought the tree back inside and a week later it looked like there were even more mites than before. I've put the tree outside for the past few days because I don't know what else to do. Suggestions? I think the nursery might have a generous return policy, although I'd rather not give up on the tree. Thanks for reading.

spider mites like it warm and dry, and if I remember right are particularly susceptible to insecticidal soaps. You can use something like Safer and follow the directions, or make your own with a spray bottle, a tablespoon of rubbing alcahol, and a teaspoon of something like Ivory or Dawn soap. Let the soap sit in the water over night to dissolve, but add the alcahol immediately before use. Some folks like to add a little tobasco sauce to the mix, a couple drops will suffice, but I usually just use soap and rubbing alcahol.

Also, pay attention to the night time temps for the tree. It will need as much sun as you can give it inside, but it also needs at least a five degree drop in temps at night. In other words, if you keep the room at 65 degree during the day, try and make sure the room temp drops to around or below 60 at night. Putting it next to a window opened a crack will give it both fresh air and a cooler night temp, which will help the tree out in the long run.

Most citrus actually prefer cooler temps than that in winter- night temps around 55 will do wonders in keeping them happier. For this reason they are really better suited to a conservatory or barely heated greenhouse than to typical house temps. Well, unless you are like me and like it cool to sleep *grin*.

At any rate, lowering the night temps will help the tree stay healthier, which will in turn help it deal with the mites with its own natural defenses. Thar will only help so much though. A spray bottle with soapy water and a sponge to wipe down the leaves will also do it a world of good. Be careful of leaving it outside overnight though... it really is too cold out at night for it without protection this time of year. I don't usually take house plants out till mid May.