Control spider mites with soap and oil sprays. Confirm the mites’ presence by trying to knock a few off of the leaves and onto a sheet of white paper, then observe them moving around. Mix 3 tablespoons of dishwashing soap with a gallon of water and wet the leaves thoroughly. Wash off the soap solution after a few hours. Repeat every five days.
Hand-pick stink bugs and drop them into a container of soapy water. Nymphs feed shallowly on trumpet vine leaves, while adults cause deeper damage.
Ignore planthoppers, which are thin insects shaped like a guitar pick. These insects do not cause serious damage to trumpet vines. If you are bothered by the sticky liquid planthoppers excrete, you can disperse the bugs with a strong stream of water from a hose.