I don't know where they came from. Possible the outside planter where I was growing celery on the deck for the tasty leaves until October. Maybe a few on the Endive lettuce leaves I brought inside about the same time.

But the darn things have plagued me inside ever since Mid Winter. I spray with insecticidal soap. I rinse everything with strong water spray in the bathtub the next day. I spray the bathtub with soap.

I keep plants apart and the damn aphids find them anyway. I can't seem to get rid of these things inside the house and I've never had this level of problem before. I know what normally works and I can't find where they keep coming from. I've checked all the other houseplant leave above and below down to the roots with a magnifying glass.

Are they just in the soil?

I may be missing something here. Any suggestions?

You might try an oil spray designed for indoor plants. Here is one:
http://www.truevalue.com//cata...

They wouldn't be in the soil unless they are root aphids, and if they were root aphids you wouldn't be seeing them on the above ground parts. They probably came in with the plants in the fall. Once indoors they proliferate because of comfortable temperatures and no natural predators. It's difficult to blast them off the soft tissue of plants with enough force without damaging the leaves, they can really hang on. Aphids may nor may not have wings, have you seen any winged forms? If so that'll likely be how they're getting around.

sooby said:They wouldn't be in the soil unless they are root aphids, and if they were root aphids you wouldn't be seeing them on the above ground parts. They probably came in with the plants in the fall. Once indoors they proliferate because of comfortable temperatures and no natural predators. It's difficult to blast them off the soft tissue of plants with enough force without damaging the leaves, they can really hang on. Aphids may nor may not have wings, have you seen any winged forms? If so that'll likely be how they're getting around.

The aphids are green, but I have seen tiny black winged flies around. I thought they were fungus gnats. Is that where I'm missing them?

The aphids with wings would be the same size as the largest of the non-winged ones, so maybe you have both aphids and fungus gnats. Could you be inadvertently transferring the aphids yourself, such as with a watering can?

Are you seeing any ant traffic around these plants?

All soap and water will do is give you clean aphids.
They could come from your house, a neighbors house, who knows. They travel on the wind.
Bayer's 3in 1 insect spray, follow directions, three sprayings, a week to ten days apart. Spray all the soft tissue parts of your plants. Leaves, tiny stems, etc.

BigBill said:All soap and water will do is give you clean aphids.
They could come from your house, a neighbors house, who knows. They travel on the wind.
Bayer's 3in 1 insect spray, follow directions, three sprayings, a week to ten days apart. Spray all the soft tissue parts of your plants. Leaves, tiny stems, etc.

Well, actually, the insecticidal soap worked great. It just took a few days. Now all I have to do is snip off the celery leaves with the dead aphids on them and let new ones grow.

I can sympathize. But honestly here in Florida back in 2009-11, I thought I was raising aphids!
They were everywhere. The orchids, the hibiscus, the plumeria, the tibuchinas! It seemed like 100's per branch tip. I use Neem Oil now as a monthly preventative since then: no aphids, no mealy bugs, no false spider mites, and it is safe to use.
But as with any treatment you choose, diligence, especially in the beginning is critical. If you are not faithful in your control, they will beat you every time.
After 6 years now if I miss a treatment, I do it the first weekend of every month, or I spray the next weekend, it is no biggie. There are no insects to suddenly explode into a problem but I know several people who use my treatment occasionally and have trouble. They do not spray faithfully, but spray when they remember to. They have no luck controlling insects who have a weekbto ten day life cycle and their population can explode overnight it seems.
Insect problems go hand in hand with growing plants. Just how it goes.

I use only soap to kill my aphids all the time. It will only kill the live bugs, not the eggs so you do have to apply it about 3 times say 5 days or so apart. For smaller potted plants, I'll fill a bucket with soapy water and just dip the whole thing, I find that easier than spraying. http://mg.ucanr.edu/Social/?bl... Although he cautions, I do mix my own with Dawn dish soap (not anti-bacterial, regular like they wash the otters and birds with). It can damage some leaves as he cautions (he notes most susceptible plants). Works like a charm for me. We've had warmth here and I've just been doing it this week.

So, after 3 sprays a few days apart on the celery (which I grow inside under lights for the tastey leaves) I finally saw no aphids. I even examided the leaves over and under with a magnifying glass. I snipped off dead leaves and threw them in the trash in case of eggs (and trust me, putting anything compostable in the trash is really hard).

My biggest concern was that the aphids were getting from one flat of seedlings to another. But that also seems to have stopped finally. I think I got the last ones 4 days ago, but am watching carefully. Sorry if I panicked a bit, I was having a real problem here that was beyond any aphid problem I've ever experienced.

Thank you all for the helpful advice...