Dish soap makes a safe, effective homemade insecticide, the same as insecticidal soap.
Dish soap isn't the same as insecticidal soap. Detergents strip the leaf's protective wax and can damage foliage, so the "safe homemade spray" idea backfires. If you want a soap spray, use a real insecticidal soap; it works on contact against soft-bodied pests like aphids.
What is actually known
Dish detergents are not insecticidal soaps. Insecticidal soaps are potassium salts of fatty acids made for use on plants; detergents are degreasers that can damage plants by dissolving the waxy cuticle that protects the leaf, so the "safe homemade version" framing is exactly backwards. If you want a soap spray, use a labeled insecticidal soap, which works on contact against soft-bodied pests such as aphids.
The evidence
Evidence: checked against 1 source in the research-based literature.
The source
Dishwashing soaps and detergents are designed to remove grease from dishes and may cause plant damage by dissolving the waxy cuticle on plant leaf surfaces
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Milpa Gardens. “Dish soap makes a safe, effective homemade insecticide, the same as insecticidal soap.” Evidence grade: Refuted. https://milpa.garden/beliefs/dish-soap-insecticide-soap-spray-bugs/
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