Insects are by far the most species-rich
Earth. To date, 950 000 insect species have been described
and many millions await discovery (Groombridge 1992).
Insect species are estimated to account for more than
half of all species on Earth, and beetles alone currently
represent a quarter of all described species (Southwood
1978; Stork 1988). Due to our very limited knowledge
base regarding the exact number ofspecies of insects, their
distribution and rarity" only a small number of species
have been listed in regional and global conservation lists.
It has been estimated that 44 000 extinctions of insect
species have occurred in the last 600 years, but only 70
such events have actually been documented (Dunn 2005).
Of the predicted 29 000 insect species endangered or
threatened in North America alone, only 37 are included
in regional red lists (Redak 2000; Dunn 2005). Overall,
the diversity of insects has received very little attention,
due not least to constraints in time, energy and funds to
thoroughly investigate mega-diverse insect taxa. Their
small body sizes and variability in colour patterns mean
it is difficult to identify insects and makes insect diversity
studies more challenging than studies on vasculm plants or
vertebrate species.