It's not the number of bugs it's the type.

If I actually see a single Apple Maggot Fly you can bet there are many more. One on the wing is too many. Three fresh ones on a trap is probably time to spray.

I could see a swarm of Picture Wing Flies and it wouldn't be an issue because they're not an issue. Most of what you list is not an issue in any number.

Consider yourself lucky to be able to grow fruit trees in Idaho. Here in the east, its tough getting by without several sprays of chemicals. There are just too many pests to get by without.

If i had my way, i'd move to the low desert and grow fruit. Not to mention its either too humid (summer) and too cold (winter)...only time we get a break is spring/fall...

with all this rain comes pests and diseases... I'm seeing a ton of powdery mildew because of weeks and weeks of heavy rains, clouds and high dew points.

I know the insects that I am seeing are not a problem, that's why I leave them alone. I was just kind of wondering if those who spray more often still see insects on their trees or if the sprays completely wipe them out. I also wonder if the ones that are munching the leaves are possibly spreading disease. Again, since I have seen no harm (other than imperfect leaves) I don't worry about it too much.

I've actually been thinking about further reducing my sprays because I've seen no damage at all to the fruit in the past 3 years. Right now I just use 2 sprays, one shortly after petal fall (early May) and another when it starts to heat up in early June and I start to see some insect activity. I've basically just been following this schedule because it was recommended to me by a friend who has grown fruit here for many years. I have been thinking about cutting back to 1 or no sprays just to see what will happen, but I'd hate to see the bad bugs come in and get established and fight me every year. An ounce of prevention...

I still see insects.
I'm amazed I see so many fly types since once Apple Maggot start I start spraying pretty consistently.

One thing about areas that get plenty of rainfall, you get tons of bugs, no matter what (or how much) you spray.

At times I spray weekly and still see moths coming up out of the grass when I mow.

Mosquitoes, deer flies, chiggers, we have them all. In the fall we have those fat spiders that hang about shoulder height from trees at night. Amazingly, they can see you approaching and generally run back up in the trees before you walk into them.

A broad spectrum insecticide will pretty much kill all the insects on a tree, but it doesn't take long for the bugs (good and bad) to migrate right back in.

Olpea-

Exactly. Its kind of like dropping a nuke on your tree. You basically vaporize everything, but outsiders will move in when they see greener pastures. I figure someday (hopefully when i'm long gone) that mother nature will fire off a few supervolcanoes (Toba type event) and get rid of most humans :)

Part of it is just numbers. As long as the destructive pests aren't excessive, they usually aren't a problem (except for PC...they can lay a lot of eggs per female).