Cinnamon extract is the key ingredient. For Brookn's recipe.
When I experimented with it, I used less or more of the ingredients and got different results.
When I used the same amount of extract and more soap it killed some bugs but not all. It did nothing for the snails or slugs.
BUT When I added a little more (not much more!) extract
it killed the bugs, the slugs, (melted them like ice cream on a hot day-GROSS!), everything! Even La Cooka Racha Cockroach I found in an oncidium that I bought! YUK!!!!
Now I use it as a pretreat for every plant that I buy
and as a preventative wash for all the orchids that I have.