Question
QUESTION: I live on the third floor of an apartment building in West Los Angeles, about five miles inland, with a southwest-facing balcony, where I have herbs, kalanchoes, a Christmas cactus and a large jade tree. All of them have become infested with mealybugs, whiteflies, tiny black bug and green aphids, despite repeated applications of, first, essential oils, then insecticidal soap, finally bug-killing spray from the garden center. The pests just keep coming back (obviously I'm not using the herbs). I'm told I will have to sacrifice all the plants and start over. Is this necessary? And if I do, what will prevent the horde of pests from coming back?
ANSWER:

This is an extreme problem. There is something that is attracting them to YOUR plants. You will need to get rid of that attraction, and put up some kind of barrier to keep them away.

Bugs are attracted to smells. color, and moisture. Soils with moist, decomposing soil, flowers with bright colors, and water sitting in containers. Bugs can be brought in by bug infested plants, or soil, or by other bugs, or birds. Ants will, for exmample, carry aphids from plant to plant. So, just when you think you have killed them all, the aphids return. So you would need to kill the ants as well.
With such an extreme infestation as you have described, you are going to have to take extreme measures to solve the problem. It all comes down to " how important are these plants?" Are they worth the trouble?

Remember, I said get rid of the attraction, and put up a barrier. Well, this means starting by, completely cleaning the plants with soapy water, then heavy rincing, and adding fresh soil. Add systemic insecticide to the fresh soil, applied at two week intervals, as per container instructions.
Neem applied to the leaves, and the soil as directed on the container. Spraying the leaves with a good insecticide.
Read the instructions carefuly on the lable. This will tell you what bugs it kills, what plants to spray it on, and how much to use, and how often on that plant.

And most important, a net, or some simular sterile enclosure, that will block the bugs from getting back to the plants. This isn't very attractive, but it is a barrer that will deter the problem, and save the plants in the future.

Unfortunately, being in an apartment in the city, you are not able to use the traditional organic methods, like chickens, and other insects that eat insects.

I am sorry that the problem has become so devistating, but If you are not able to save your plants, and must distroy them, then perhaps they can be replaced with resistant plants, that you can start preventative measures with when you bring them home.

bakerplanter

---------- FOLLOW-UP ----------

QUESTION: If I do decide to start over with new plants, what preventative measures should I take right from the beginning? (and yes, I have tiny ants, and am going to put out new ant traps and spray). Thanks very much!

Answer
If it were me, I would clear out all plant material, and not get any more plants for a while. Possibly a year, to be on the safe side. Wait for the bugs to go to "greener pastures" Then sterilize the area with insecticide to make sure. Choose your new plants with care. Keep in mind that the bugs are still in the area.
Systemics added to the soil, sprays, and netting, will all give notice that they are not welcome on your plants. Keep your plants healthy, and well cared for. Bugs usually pick on weak, and sickly plants first. When you bring the plants home, clean them. Be very aware of the things that attract the bugs to your plants. Never leave water sitting out, or splash water on the leaves of the plants, or never leave the plants unattended for a long time. Check your plants daily for problems.
I only list all of this extra effort, because of your unusually serious bug problem, and the threat that it will repeat over and over. I used to have a simular problem where I live, but I am in the country, so I now have a Turkey, and Rooster, to help. Otherwise, I too would need to do all of these things that I list.

bakerplanter