First thing I always do is try to just get the bugs off of the plants. Just disrupt them -- no need to watch and let them eat your plants! Even if you just knock them off, you'll make them have to get back up on the plant again.
Use your hand, wear gloves, dust brush, old toothbrush, blasts of water when you have the hose or sprayer. A cup or pan of soapy water is very effective for drowning/eliminating anything you can get off of the plants. Larger bugs -- if I can catch them I will force drop them on the ground and stomp on them. YOU ARE THE PREDATOR.
Mass infestation like the sunflower leaf, especially when so damaged that the leaf is not going to recover -- it's just easier to capture the lot and dispose of them... Hence the plastic bag trick. If you cut off the leaf without bagging first, you'll jostle a bunch of them off. That's fine if you don't have a bag handy -- just get them off.
Flea beetles -- if you can get to them early in the morning when the dew is still on the foliage, they are slow and you can easily rub them off the leaves and squish them. If the foliage is dry and they tend to jump off, hold the soapy pan under the leaf and drive them to jump into the pan.
...it's easy to get caught up in the marketing hype and propaganda that you HAVE to have poisons to control garden pests, but that's not necessarily true...
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