People sometimes ask me how I spot all these bugs. I tell them I've had over 40 years of practice. I know where to look, and what to look for, and even when I don't, my eye can "read" bugs among the leaves, much as (I imagine) a skilled editor or proofreader spots bad grammar and spelling mistakes in a piece of text.
For example, my eyes were drawn to the bright green of this green lynx spider, which stood out from the duller green coastal sage scrub.
But sometimes, my eyes play tricks on me. My brain is always looking for bugs, so sometimes I see them when they're not really there. I'll get a little rush of excitement, and then realize it's just a twig, or a dried leaf or some other non-bug thing.
False alarm: This dead twisted peach leaf made my heart quicken for a second.
Oh yeah, the first post about my insect-finder's eye was here.