You need to use a 'true' soap. Dish liquids, and the usual body products are detergents. Look for true soaps like Castile soaps, Bonner's products, and any number of soaps you can find in health stores, etc. I buy my natural soaps from Green Mountain soap company...but don't use it as an insecticide.

You can purchase a true soap that is manufactured expressly for this purpose...a commercial insecticidal soap with real directions on the label.

If you can find it Fels Naptha is one true soap. There are a few but it is easier to make detergents from waste materials from non renewable resources than to make lye and react that with animal fats to make soap, anymore.

Doesn't have to be an animal fat. Olive oil (castile) and other plant oils are often used to make good soaps.

I wish I could remember the other brands of soap I've seen at the grocery stores, besides the bars of Fels Naptha.