Predaceous mites, and also Bti and nematodes, are commercially available through mail order from special suppliers. Potato Disks Fungus gnat larvae migrate to feed on the underside of potato pieces placed in media. Pick up and examine the underside of each potato and the soil immediately beneath it about once or twice a week. Compare numbers of larvae before and after any treatment to determine whether larvae are being controlled. Numbers of insects caught often are not a good indication of the number of pests infesting plants.
Sticky traps are unlikely to provide pest control.
Orient vertical traps so their bottom is even with the top of the plant canopy. Regularly adjust traps upward as plants grow. Hang traps from wires or use clothespins to clip the trap to a stick placed in media. Inspect traps at the same regular interval, once or twice a week. Count and record the number of each type of pest caught.