In case it isn't clear, the peppers overwinter in my living room in a south facing window.

Sounds like you're doing everything right. Insecticidal soap has always worked for me. I soak the plant pretty good, let it set for a bit, then rinse. Repeat every 2-3 days until they're gone. If you suspect some other houseplants as the source, are you treating them as well, or just the infested peppers?

How big are the plants when u r over wintering? Do you have pics?

I just sprayed my Black Pearl this afternoon with Neem Oil....and then I sprayed my Hungarian Wax for good measure, even though I didn't see any aphids on the latter.

That's about the best method I've found....spray, rinse, repeat, as Tsheets mentioned. Treat plants *before* the infestation occurs.

Josh

Do you have ants? I know first hand in a greenhouse the aphid can be just a symptom of another problem. Placing traps can help I tried a sulfur bomb years ago. DO NOT DO THIS it was a sad site . Thank god my peppers cam around [weeks and weeks later] I hate aphids. Some people dip there plants getting all those arias those SOBs can hide.I would NUKE THE BASTARDS only they would only be replaced by pepper eating cockroaches .Aphid control is an important part of pepper propagation and I for one am always looking for a better way. None last year Knock on wood.

neem oil will not help prevent aphids. It will not kill the eggs.

Neem Oil will kill the aphids.

Josh

Josh, I'm not sure if that post was for my benefit but you are correct It will kill the aphids but to use neem as a preventative is not a good practice because it will not kill the eggs.

Best thing I ever used- Diatomaceous earth (DE). Doesn't harm the plant like oils or soaps that can strip off the natural oils on the leaves making them more susceptible to insect infestations. DE dries out the eggs and and cuts them up as soon as they hatch. Use the fine ground powder specifically for insect control, not the chunk DE that you get as oil absorbents.
-Eric-

Yep, I was clarifying that the Neem recommendation was to kill the aphids themselves - to prevent an infestation by crushing the numbers and possibly disrupting hormones as soon as the aphids appear. Neem has many properties and will deter certain pests - but I don't think aphids bite deeply enough into the tissue to get a strong dose of the active ingredients. Which is why the Neem is used as a simply suffocant in the case of aphids. It takes times, though, it's not an overnight cure.

Josh