if you look back into history you will find neem was the only thing that lived after the locust destroyed everything,also if you look into it you will find neem is also in most medications ,bath soaps and lotions ,even in some foods we eat,i use neem cake and yucca,both combined is a recipe for dead bugs ,i have found they dont even want to come around my plants indoors and outdoors,use recommended amounts and you will be pleased,and the main thing they arent chemicals,you cannot foilar feed with the neem oil when you have flowers indoor or outdoors,this is the reason you add to your soil,and plant naturaly uptakes it,hope this helps ,i dont like chemicals
I use neem pretty heavily, and I still observe a ton of microlife in my soil. I add it to the worm bin, etc with no problems.
Neem seed meal is the left over part of the seed after they squeeze the oil from the seed. I don't know about earthworms attracted to it, but it is a staple in my garden.