| I don't know that there is a technical definition to differentiate between attractor and
searching flies. I would define searching flies as flies that
imitate an insect or stream organism that is consistently
available to trout. For example, an Adams is used to imitate a
general upwing mayfly and an Elk Hair Caddis is used to imitate
downwinged caddis. Both of these flies represent an insect type
that is consistently available to trout and they may be moved to
strike these flies when the insect in not hatching or is hatching
in limited numbers.|
I would also add flies that imitate crustaceans like scuds and sowbugs which are always available to trout in the drift of southwestern spring creeks.
Many might consider all nymphs to be searching patterns seeing they are always available.
Terrestrials are one of my most used searching patterns. Casting to likely looking holding areas will often draw strikes when fish are not otherwise rising. Attractors are flies which may have a resemblance to an insect type but generally have unnatural coloration. I can't explain why a trout may strike a Royal Coachman because it's coloration doesn't resemble any streamborn insect but they do catch fish. These flies are often effective to draw surface strikes when nothing is hatching, during sparse hatches when fish are not selective, and at times, during heavy hatches when they simply stand out from the natural and grab a fish's attention.