Interesting. Feldon is exactly right, that BT (bacillus thuringiensis), a bacterium that affects only some caterpillars and insect larvae, is completely organic.
We now have illustrated what I think of as three different types of gardening/farming:
What we tend to call conventional/ traditional, but has only become "traditional" in my lifetime, since WWII. I call it chemical gardening: Gardening in monocultures ( a field that is all one crop, e.g. corn), plowing/tilling, synthetic fertilizers, chemical herbicides and pesticides.
Organic gardening- Probably still monocultures, probably still plowed/ tilled, uses things like compost / manure/ compost tea instead of synthetic fertilizers, uses hand weeding or things like vinegar, citrus for herbicide, Bt and things like garlic-pepper spray for pesticides, no synthetic herbicides and pesticides.
What I call ecological/ natural gardening, related to things like permaculture and biodynamic gardening: No monocultures, very diverse plantings, no tilling, composting in the field, mainly using only what comes from the field and mulch and cover crops, companion planting, trap crops, interplanting, beneficial insects, use of birds, toads, ducks etc to control pest populations, chicken tractors for fertilization...
So the chemical gardener sees the hornworm and reaches for some kind of poison spray. The organic gardener sees the hornworm and reaches for the Bt spray. The ecological gardener sees the hornworm and tries to figure out how to adapt the garden ecology to keep everything in balance, and probably doesn't spray anything except water.
Of course most of us exist somewhere along this continuum and are not perfectly any one 100% of the time!