If you have folded paper towels or newspaper on top of the substrate, the mealies will gather in the folds, and you can just pick it up and shake them into your feeding container. Or use an empty paper towel or toilet paper roll. They love to crawl in those. Makes a handy scoop full of worms. Or put a fresh piece of apple or carrot in. In 10 minutes, there are a hundred or so glommed onto the fresh food. Pick it up and shake into the bowl.