I have a variety of plants in my house that have had populations of a small, weak flying insect that sticks around the soil on my plants. I thought they must be fungus gnats, but they don't have the appearance described by common guides to fungus gnats. Particularly, the insects I have in my house are primarily yellow with black blocking on the back, and they lack the distinctive Y-shaped vein in the wings. I was going to apply Bti as a biocide to treat the affected plants, but wanted to confirm I am seeing fungus gnats before application. I have a hydroponic garden that is currently idle, clean, and dry. I want to start that hydro garden again soon, but want to treat the insect problem before I add this chronicly wet garden back to my house's ecosystem. I did recently replant a few orchids with new potting soil that I suspect may have been the source of the new pests. Please let me know if you can confirm I have fungus gnats, or if not an identification of the pest. Thank you.