Yes, you do want to use a simple soap. Your new soap will be fine. Just make sure to spray the undersides of the leaves, because that is where most of the aphids will be.

Lorna

The FAQ from the organic forum suggests: Only use natural soaps or Murphy oil soap or mild liquid dishwashing soaps like Ivory. Soap help make teas stick better to plants and pests, and they also paralyze many insects in direct contact. Use no more than 1-2 cups of soap per gallon of water. Do not use much on flowering fruit or vegetable plants. Can hinder fruit production.

That is a typo in the FAQ on the soapy mix that never has been fixed. It is supposed to read "never use more than 1-2 tablespoons of soap per gallon of water". BIG difference. 1-2 cups of soap will kill most anything including the plant. ;)

Dave

I agree. It only takes a few drops to kill a lot of bugs.

Thanks everyone! Now I'm wondering exactly what I used last year. Probably any old thing in my cabinet. Oh well, I'm still here so I clearly didn't poision myself.
STacey

Only one word of caution to add. Before using a soap solution on aphids, you might want to inspect the plants for aphid predators, such as ladybug or syrphid fly larvae. If they are present, the spray would kill them also... and they represent the best long-term solution for aphid control. Sometimes, all you need is patience, and Nature will take care of the aphids.

i was infested with aphids a couple of months ago,i used dawn dish soap spray mixed with water ofcourse but only when you got huge clusters of them cause it burnt some of my plants,so just mix it good with water and be carefull but it does work it even killed stink bugs.then after spraying i just inspected the leaves and smashed what was left with my thumb,i havent had a huge problem since only a few here and there,nothing to cause any real damage(not like the white flies)hope this helps!

I had a bad infestation of a tiny dark something on chrysanthemums and washed down twice with just the hose and they returned shortly. Third time I washed them down with the fertilizer attachment on the end of the hose and have not seen them return. Perhaps it is just the third times charm affect or perhaps the fertilizer lowered the surface tension enough to be more effective.

Stacy, read what Dave posted! I almost killed mine by using to strong a soap mix. I wanted to use Black Flag but Jeanne demanded I try the soap first.
Grrrrrrrrr, I will make her eat STORE bought tomatoes!

I know this is an old thread, but I wanted to chime in anyway. I just sprayed about 5 trees with what I had, Softsoap brand Juicy Melon hand soap.

I hope it works okay. I used an Ortho Dial-A-Spray and set it to an 8oz setting. I sprayed all of my citrus trees, since I have a pretty bad infestation with hordes of ants following. I've tried a Neem oil regiment, but it didn't seem to have much affect.

Also, I still don't know why my aphids do not attach to the bottoms of leaves as everyone states they should. All of mine attack the branches themselves, and I never see any under leaves. The whole branch gets spotted with aphid dots. The only thing on the leaves is the honeydew droppings and sooty mold.

Here's a very informative page about using soaps.
http://www.ext.colostate.edu/pubs/insect/05547.html