I just called Rainbow farms that produces much of the mealworm castings in the LA area and the lady I talked to said the bags of castings, which are mostly the skin molted off the growing mealworms, do usually have some live darkling beetles and live mealworms in them, but she didn't know if they would be harmful to a garden. I don't want to use this stuff if suddenly I will have beetles and mealworms eating up my plants and vegetables and fruit. So does anyone know for sure if they would be safe to use?

I can only speak from my experience but in the time Ive had a worm bin I havent harvested the castings, I leave them in the bin and only take some out as I need them so there's always been a high percentage of castings in there. Ive never noticed any problems, the worms are happy and healthy and seem to like it down in the castings where it's always nice and moist If the worms were unhappy or trying to leave then I would suspect a problem but it's never happened

I think worm castings look a bit like chopped cigarette tobacco. If your bin is white or if you have ever kept worms in a light color container with a cover for a couple of days the sides of the container above the food level will have 1/4 inch castings on them. You should be able to see individual ones. Even when harvested you should be able to see the individual ones depending upon what harvesting method you use. Coffee grounds would be maybe rounder? It all depends upon how close one wants to look. I know one thing. However good your vermicompost is this week, if you stop feeding for a week and let the worms work just on what you plan to harvest, you will like it even better in a few more weeks. When I am in a rush for compost I put some in an old plastic easter basket with good sized holes in it and shake the material. What falls out is my harvest. What stays in is put back on top of the bin. I almost think this partially processed material is very good for the health of the bin. It balances out the excesses in all directions, too wet, to dry, to acidic, of new additions. Good luck, hope you have some already.

castings are a soil amendment that will keep the vital bacterial population happy .... Miracle Grow is a chemical stew that will eliminate the bacterial population ... commonly castings are added to garden soil in small amounts near individual plants, some folks do add them to potted plants, usually by scratching a small amount into the surface sounds like by "juice" you mean leachate, the excess liquid draining from the bin and taking some of the nutrients with it ... it's best used to add back to the bin when it's tending to be dry, it's NOT "tea" the pH of finished castings, like any type of compost will tend to be perfect for plants, very near neutral or very slightly acidic, which is what the bacteria prefer Bill