If water-blasting the leaves doesn't get rid of enough insects to satisfy you, the next step is to try liquid soap. Garden shops sell special insecticidal soaps. You can also use liquid dish soap. My favorite is Dr. Brauner's Peppermint Soap, sold at health-food stores. It smells great and is more biodegradable than some soaps.
Insects carry their skeletons on the outsides of their bodies.
Soap clogs their pores, suffocating them, but doesn't harm you, your plants or the environment. However, even with soaps, you should test a couple of leaves first, especially on a prized or rare plant, or something that might be sensitive, such as a fern or African violet. If this doesn't work well, you can try horticultural oils, or safer products such as those with neem, a plant-based compound. Go to your favorite garden center and ask what they recommend. You can also call Desmond Ogata at the UH-Manoa plant disease clinic.