I dont think they have a whole lot of nutrients, probably calcium and phosphorus, mainly the latter as far as I know. I have been a reptile hobbyist for years,and they are food. They are probably mixed with plenty of sawdust right? That would have carbon, or humus. But they need plenty of nitrogen to balance them out.

Is this place you get the mealworm castings from located in Compton? A friend recently told me about such a place but he said they also have worm castings. He said it was on Alameda but I drove around in the area (ratty neighborhood) and I couldn't find it.

He grows heirloom tomatoes and seems to think the mealworm casting are beneficial.

Yes, it's the place in Compton, Rainbow and yes, it's a little hard to find but if you call they will tell you how to weave your way through the neighborhood. I first read about them in some article for teachers (I'm not) and got 20 or so bags a couple of times once a year (each bag weighs about 25 lbs) and I've used it to mix as a soil amendment both for flowers and vegetables and it has definitely helped. I live on the west side of LA and have clay clay clay soil, and it has definitely helped that a huge amount. I've written to many of the local state smart gardening links and the master gardeners around and best and most specific answers I got were that the composition was 3-3-3, and other scientist type told me "they are what they eat" which would include bran. The castings are sort of like sand but there is definitely a manure type scent, especially when wet. My little worm factory worms love the castings and worms definitely are attracted to the castings. So, I know they help my yard and recommend you give them a try. For the company, it's not their cash product and I know they are used to people picking them up and that has been going on for years. Let us all know what you learn.

Thanks. I found them on the web. Link is below - Mike

Here is a link that might be useful: Rainbow Mealworms