[Subversive_plot]

I have heard that washing up liquids that have simple ingredients and no perfumes can be used effectively as insecticidal soap.

I found a web site that discusses one of the washing-up liquids sold here (Ivory Liquid) to mix as an insecticidal spray (fragrance-free, "pure" ingredients).  The mix proposed was 5 tablespoons to 1 gallon of water.  That sounded like a lot of soap.  The article said to use on an inconspicuous leaf then check after 24 hours for leaf damage (if yes, use a lower concentration).  The Encyclopedia of Entomology indicates this soap brand is effective on insects.

I need to use something soon on some tender-leaved lettuce (for control of black aphids).  I was wondering if any of you have experience using lower concentrations of washing-up liquid?  I would prefer not to damage any lettuce if it can be avoided.

I was thinking of spraying late in the day, near sundown, then hosing the soap off the next morning.  I am open to any suggestions.

[Subversive_plot]

Sometimes I learn a good bit from the "Similar Topics" beneath my original post.

This time, I think I learned that (unwittingly), I broke an 11th commandment:  "Thall shalt not use products for their unintended/non-approved use, especially in the garden, even if it's perfectly harmless".

So, I'm left with a dilemma. I have accidentally made (or might accidentally make in the near future) a solution of a half teaspoon of washing-up liquid to a liter of cold water.  Having accidentally made such a solution, I will NOT use it for insect control. That might be a violation of the law (I'm not sure what the extradition laws are regarding serious crimes of this type, i.e., illegal use of washing up liquid).

I will re-purpose the water, carefully applying it to some lettuce with some small black dots on the leaves (very tricky dots - some of them move occasionally).  The water will be applied as a cleaning agent to remove the dots, and possibly as a sticking agent for a foliar feed of the essential plant nutrient, dihydrogen monoxide (I've been advised that lettuce can't survive without this nutrient). 

I will see if the cleaning agent works to get rid of the black dots. If it doesn't get rid of the dots, I might accidentally make a stronger solution.

Let me know if I stuck the landing on this one. 

[AndyRVTR]

I remember a lot of years ago, my older brothers used this method in their allotments, it was the 'go to' way of dealing with aphids. But, I also remember it was a weak solution, like 1 teaspoon of Fairy (other brands available) to a gallon of water and then put into a 5ltr pressure sprayer, shook it up so when it was sprayed on the plant, it made lots of soapy bubbles. It was the soapy bubbles that covered the aphids which in turn suffocated them, if memory serves me I'm sure this was done quite regularly to keep the numbers down.

[mumofstig]

The 'thou shalt not' rule was mainly pre-Brexit, it's not used as much nowadays  (unless people are suggesting something that is actually dangerous  )

I just use a few drops of a 'gentle' washing up liquid to a hand sprayer of water to spray the inevitable blackfly on my climbing beans. Works a treat 

[Plot 1 Problems]

I make an all purpose bug spray with a tiny squirt of washing up liquid (nothing fancy, cheapest going), garlic and coffee grinds (strained out before using) spray it liberally over my beans and greenhouse crops and tends to stop most of the bugs.

[JayG]

There's a lot of conflicting information 'out there' as to whether the detergent in washing up liquid works as well as real soap solutions, and also whether either damages the leaves of the plants.

All I can say is that for me it does the job well on both broad and runner beans without any obvious collateral damage - I use a 'squirt' (probably about a teaspoonful) to a litre of water in a hand sprayer.
Sometimes have to repeat if the colonies have really established themselves by the time I get round to it (which is usually exactly what does happen!  )

I do check before spraying that there are no ladybirds or their larvae on the plants - I wouldn't want to stand in the way of their good work, but have to intervene because in most years the aphids have a big head start over them.

[Subversive_plot]

Yes Jon, that is what has happened for me.  With a sudden warm spell, the aphids have appeared, with no opposition.

The heroes in your post, we call them "ladybugs", here, or the entomologists (like my son) call them lady beetles.  I suspect they were called ladybirds over there before they were called anything in particular over here.

[Hampshire Hog]

I have used pure water in a hand sprayer which might by mistake still contain the remains of washing up liquid I had used to clean it!! For some reason this works very effectively to deter black fly etc. Naturally I wouldn’t intentionally use a very dilute solution of liquid detergent to deal with pests. 

[rowlandwells]

we've used washing up liquid as an insect spray for some years I've  even made my own spray containing Garlic powder  chilli powder and washing up liquid and it seemed to work ok on our brassicas but for broad beans just washing up liquid I'm not a member of the nannie club so I don't take any notice of some of the tat that's said about spraying I tend to do my own thing the main thing is to get rid of those pesky aphids so we spray on a regular basis