The attempt to plot the distribution of a shifting population of insects from
inadequate data supplied capriciously by microlepidopterists offering limited
coverage of their field may not seem worth while, but it has been made and for
the majority of species a reasonable picture of their status in the county has
resulted. The reader must, however, remember that the maps have serious
limitations.
The pattern of coverage
In spite of these limitations, the accompanying map showing the number of
species recorded from each square gives a fairly accurate picture of the true
pattern of species diversity in Essex. Fuller recording would reduce the margin
of difference between high and low yield squares without significantly altering
the pattern.
Coastal squares which contain little more than virtually treeless arable
farming and salt-marsh inevitably have few species. Not much importance
should be attached to a paucity of species in squares which border on other
counties. The maps for the microlepidoptera differ from those of the macro-
lepidoptera in that they show only species recorded in the Essex section, and if
this is small it may lack variety of sites which are accessible for recording.
Map to show the total number of species recorded from each 10km square in Essex.
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