The angel trumpet, or Brugmansia, is an ornamental shrub to small tree in tropical regions and is often grown as a houseplant for its large, fragrant flowers. Several insect pests can invade and damage angel trumpet plants.
Caterpillars, which are the larvae of butterflies and moths, chew large, unsightly holes in angel trumpet leaves. Spider mites come in a variety of sizes and colors, but all are small–1/60 of an inch long–and form webs on the plants they inhabit. Mealy bugs are small, fuzzy and white and suck the fluid from angel trumpets.
Insecticidal soap is a natural insect-control remedy that effectively kills insects such as spider mites. You can buy it pre-mixed at nurseries or make your own by combining 1 tbsp. dish soap with 1 qt. of water. Spray every day until all signs of the insect are gone.
Bacillus thuringiensis (Bt) is a natural soil bacterium that kills caterpillars on plants such as the angel trumpet. It is sold as a white powder that you dust on your plant and is most effective against small or young caterpillars and similar types of insects.
Colorado State University recommends using dormant oil, as an alternative to insecticidal soap, to control spider mites. You can also spray your angel trumpet with dormant oil or delayed dormant oil to control mealybugs, which have a tough shell that prohibits insecticidal soap from entering their bodies.