Is it normal to have many different insect pests in one garden? Is it a sign that I am not taking care of my plants well? Everything looks fine except for one infestation after another!
As far as I am concerned it is perfectly normal to have all of these pests (because I also have many)! But some gardeners are more ruthless than I am. They would rip out the plants. Others would assault their garden with chemicals. I prefer the middle ground of tolerance of some damage and using low-toxic controls.
The mantra these days is RIGHT PLANT RIGHT PLACE and HEALTHY SOIL = HEALTHY PLANTS. For further information (and support) go to the Seattle Public Utilities website, which has a number of great publications on Natural Lawn and Garden Care.
There are lots of links to browse.
There is also information about Natural Pest, Weed, and Disease Control.
Other good resources are Toxic-Free Future (formerly known as Washington Toxics Coalition) and Northwest Center for Alternatives to Pesticides.