It all depends on the bug...

If its just a few plants - its generally easier to just pick them off, its faster than spending time figuring out what you need and buying it (in that time the bugs have eaten more).

Otherwise a thing to try is soap with various essential oils applied with a hose end sprayer. Oil of Citronella,(Pepper)Mint, Lavender, Neem, Tea Tree, etc. all have their merit depending on what you are after.

I would imagine the peroxide works at a slightly higher concentration than the typical off the shelf (too strong would be bad as well though), thus lending itself to a handsprayer for a limited number of shrubs, or an individual tree...

Back to the health - this is generally what draws the critters in (sort of nature's refuse collector), so besides knowing the soil, apply the appropriate foliar feed.
Some corn syrup, Tblsp of Fish Fertilizer, tsp of Boric Acid, well diluted into several gallons. The Boric Acid acts like DMSO for plants to get the Sugar into the plant cells.