A good field guide
(right) is the best reference source for
non-specialists to identify
an unknown insect or spider. Field guides
generally have photographs, distribution maps and life
histories for the common species in a particular area,
organized in some logical grouping.
Field guides usually are
written for a particular region such as North America,
or the eastern US, or the western US, and so on. They
can also specialize in a particular insect group such
as beetles or butterflies.
In general, the more
specific a field guide is in terms of group and
regional coverage the more detailed the information
will be, but this comes at the expense of broad
coverage. So, for example, a field guide of the
beetles of Oregon will contain far more detail about
the beetles of Oregon than will a field guide about
the insects of North America. I like more narrowly
focused books because they give me the detailed
coverage I need but they can be more difficult to use
until you are somewhat familiar with the topic.
Field guides are highly
individualized in that what works for you may not work
for someone else. Each publisher and author has their
own way of organizing the same basic information so
don't be afraid to compare field guides until you find
the one that suits you.