INTRODUCTION
Why the macrolepidoptera and microlepidoptera are in separate lists.
"Much thought was given during the planning of this guide as to whether the
microlepidoptera, of which there are nearly 1,500 species on the British list,
should be included. But it was realised that our present knowledge of the Essex
species is still strictly limited and that status summaries would be so incomplete
that their publication could not be justified" (Firmin et al., 1975:21). ...The
Panel is to continue in being and its objectives will now be ...secondly, to
compile, with a view to eventual publication, a list of the Microlepidoptera of
Essex, our knowledge of which, although sparse in many areas of the county, is
now growing steadily (Crittall in Firmin et al.. 1975:8).
Can a list of the microlepidoptera of Essex now be justified?
Since the above words were written, the literature has been searched and an
extensive programme of recording in all parts of the county initiated.
The number in the present list has risen to 1,052. This represents 70% of the
British total. Firmin et al. (1975:22) gave the number of macrolepidoptera as
690, which is 68.5%, but recent additions have raised the percentage to that of
the microlepidoptera. This does not mean that the smaller moths are now the
more fully recorded, for there is reason to think that they are better able to
survive in intensively cultivated country and therefore predominate over
the larger moths; it does mean that the gap in recording, if it still exists, is a very
narrow one.
Recording is not concerned only with the number of species, but aims to give
as full an account as possible of their distribution within the county; it was fear
of inadequacy in this respect which led the panel to exclude the microlepid-
optera in 1975. Distribution is here shown by dots in the 10x 10 kilometre grid
squares, 57 of which cover the county. Each species is recorded on average in
13 squares. The average number of species per square is 246, but there are four
squares with over 500. These are all in good entomological country with above
average potential; not many others could match them. But using them as
indicators, we can calculate that the overall coverage is still less than half
completed. The reader must decide whether this is sufficient to justify
publication.
The recording area
Counties are artificial units created for administrative purposes, their
boundaries being changed periodically to meet new human requirements. In
biological recording change is undesirable and for this reason the Watsonian
vice-county system is widely adopted. This dates from 1852 and was instituted
for botanical recording. The larger counties were subdivided into smaller units;
Essex, accordingly, became two vice-counties, South Essex (VC 18) and North
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