Insecticidal Soap - Homemade?

I've noticed the first signs of return of sawfly larvae to my currants and goosegogs and have read that using insecticidal soap is effective against them as part of organic gardening, but this kind of thing seems a bit steep -
http://www.organiccatalogue.com/p550/INSECTICIDAL-SOAP-Concentrate-1-Litre/product_info.html

Does anyone know how effective it is? I'll pick them off as best I can of course but feel a spray would be good to add to my armoury. I reckon it must be possible to make this kind of thing at home but most of the recipes I can find are American and the soap brands mean nothing to me. Apparently it needs to be a pure soap with lots of fatty acids, but as someone who's not big on getting a wash (not with soap anyway!) I don't know how to tell from looking at them in the shop - can anyone else recommend a soap and a recipe for making your own insecticidal soap?

Thanks

 

I would try household soap,ie the old fashioned green"Fairy", I know Morrisons do their own brand , less than a £, grate it up and leave to dissolve in water.

 

I agree with @pamsdish but put a few drops of tea tree oil in it as well.
Morrisons Household soap is 65p for a two bar pack.

 

Thanks, ladies. Much obliged, I shall pop to my local Morrisons on Friday. Do you think a bar of soap grated into...what...a few litres of tap water, plus a splash of tea tree should work? Will it keep through the summer if I cover it and keep it cool do you think?

Thanks again :-)

 

Yes, it will keep but mix the soap with hot water and then let it cool. It mixes in better that way. The tea tree oil helps to stop the little blighters coming back but use sparingly. I usually put in about 3 or 4 drops to litre.

 

I use the soap method plus I add 4 to 5 handfuls of Elderberry leaves (bruised)'mix it well and spray on

 

Thanks, I'll buy myself a sprayer this weekend and give it a go.

What does the elderberry do, @Lolimac ? We have loads growing near us so I might as well sling some of that in too :-)

 

@AndyS ...they're said to be a natural insecticide....

 

Brill. Thankyou :-)

 

I use Horticultural Soap. Not especially cheap ... It includes Potassium fatty acids, which is what does the damage to soft skinned insects.

Regular Detergents (which probably includes most of the things in your kitchen) don't include soap based on Potassium, hence not so good.

The dilution rate is important because if too strong you will get Phytotoxicity which will damage the plant. If in doubt try it on some leaves and see if they react. Although I tend to allow some leaf damage, to get rid of the pest, and then help the plant to grow out of that damage later on.

 

Me too I mix that in with the Horticultural soap

Now then ... a systemic Neem oil would be just-the-ticket

 

In light of this would you say that the homemade soap discussed above wouldn't contain enough Potassium fatty acids and would be less effective then something like this the, Kristen?

http://organiccatalogue.com/product_info.php?products_id=550&osCsid=a37a6911a533eeecd0f752104160143f

If so, is that about the going rate, or can you suggest a cheaper alternative? Thanks