Remember, if you're gardening then the 'natural balance' is already out of whack. Gardening isn't natural, you see what I mean? NOT there's anything wrong with it, mind you!!

SO, it's to everyone's benefit if you help your plants keep up the battle, but do so by methods that will not disturb the natural predators. Hand removal of some plant pests is very effective, and strong streams of plain water can also be helpful.

Just remember that healthy plants can live with a certain number of pests. But once they get the upper hand, the natual vigor of the plant declines, and they (plant) find it more and more difficult to remain healthy.

Thanks for the quick reply, rhizo! hmmm, you do have a point there about gardening being unnatural. But I would like to think that I'm helping my plot of land *return* to its natural state before the day the big bad bulldozers levelled the rainforest to make way for my humble home :P

What I'm concerned about is that removal of pests will result in their natural predators *not* being attracted to my garden, therefore never achieving a good balance. Should I just "thin out" some of the pests and leave the rest be?

Unless you go for an all out war on each particular pest, you are never likely to get rid of all of them. But by helping the natural forces in your garden, your plants are much more likely to fall prey to an overpopulation of a problem.

Each of us establishes our own 'threshhold', to use an integrated pest management term. I never worry about seeing few pests. But when something seems to begin to take over, I get out the gloves, the insecticidal soap, the hose, the neem.

First, keep in mind that the "pests" are only a small part of the natural world. Around 8,000 insects out of 8,000,000 species are classified as pests and many of the others are benficial and those insects, as well as birds, eat the "pests".
Second, keep in mind that spraying any, especially the very broad spectrum, poisons upsets the natural order and kills off the beneficial insects as well as the pests. Beneficial insects generally do not show up until there is enough food, water, and shelter provided. Would you go to a resturant that had no food?
There is no need to allow the insect "pests" to devour your garden but control needs to meet the need, ie. do not spray the most toxic poison when you see one Japanese Beetle. Always start by identifying the real problem and correcting that. Determine what the problem is, determine how much damage you could live with, determine the least toxic means of control (would a pail of soapy water work?), apply that control, reassess the problem. If the least toxic contol is not working then look at the next least toxic control, always keeping in mind that even Insecticidal Soap is a broad spectrum poison if sprayed on beneficial insects as well as your "pest".
Dig in and look closely at your soil since plants growing in healthy soil are better able to withstand attacl by insect "pests" than plants growing in sick soils.