The garden hose without the detergent is rather more effective. For the home gardener mixing up your plants is a very powerful force for pest control. The work that we've done here at Reading shows that plants absorb each other's smells and that insects can even smell the difference between two varieties of brussels sprouts. I've often wondered why the home gardener has to have a miniature farm, why the plants have to be the same variety in straight rows with bare soil in between. The thing that attracts natural enemies is aphids.
Predators react to the smell that comes out of the sap excretion at the back, the honeydew.
Biological control doesn't work unless you spray early on with something that mimics the smell of the honeydew. Normally the ladybird is active at night and not too visible. When you see them it means that they are starving and rushing around looking for food. Well, the real perisher is the black bean aphid, most years that is going to need control, otherwise you will suffer very much, particularly on broad beans. That's where I get out my garden hose.