I'm not sure about all insects. I have leaned over the recent years to discover the insect that is a pest, first. I use to just grab Raid at the store and go for it until I became a gardner. Then, with good teachers and research I discovered, explored, and learned they are more friend than foe.
Some pests are just pests, I agree. However, I am much more lenient with spiders now than before. Not being agraphobic, which may be a hindrance to some, and not really all the time believing they are spies like Merlin the Magician says, I discovered they are great hunters. Seems, many of those spiders do keep the real pests away. If you would like a great adventure take a peek about.
I also learned my best friends the humminbird use spider webs for their nests. Another point. And, some are food for other bird friends too. But, if it is ants, especially wood ants tearing at the plants then I usually buy a box of splenda - works great being hydrocarbon a relative to hydrocholic acid. Take a gander at the 2nd paragraph here http://www.anh-usa.org/toxic-chemical-being-sold-a... Any hoot, though a toxcin of sorts, safe if kids or pets chance upon it, and does a long term job with ants. I have heard a few other pests too. You'll have to do a look about to see.
Cost wise, not much different than other ant chems, over the long run, especially if there is a Costco or Sam's club or something similar nearby. Oh yeah, I have no flies in my mobile home, since I have few jumping spiders who live on the window sill. Seems it is a fun event to watch them leap, snag, and spin a web, real fast.
And if you have roses or other plants with aphids order some lady bugs. They do a great job when spread early in the AM just before dawn.