The Survey
The survey commenced in 1980 and for the first three years records were obtained
mainly from the Colchester area. No clear pattern of insect presence emerged; in fact
there was no real intention of making a serious attempt to record Orthoptera in north
east Essex, let alone the County as a whole. However, as time progressed and records
began to accumulate, contacts were made in other parts of the County, mainly through
the Biological Records Centres at Stratford and Southend. These provided a wider base
from which to work and made recording on a County basis possible.
The bulk of the survey took place between 1983 and 1990 inclusive, when 85% of the
total number of records were collected (4258 out of 5001). Only 276 records were
secured during the first three years whilst a further 467 were added up to December
1995. For more detail on the recording of individual species over the survey period refer
to Table 3.
It seemed logical to present the data using 1km squares as it is then fully disaggregated,
and tetrad and 10km square records can be inferred. It was recognised that to visit
every 1 km square would be impractical and inefficient given limited participation in the
survey. An alternative system was used to try to ensure even coverage. Firstly we
assumed that it should be possible to locate 5 species in every 10km square; an
unambitious target except perhaps in the north west of the County. The species would
not necessarily be the same five but it was envisaged that the "core" species were likely
to be:
Chorthippus brunneus
Chorthippus parallelus
Leptophyes punctatissima
Meconema thalassinum
Pholidoptera griseoaptera
Secondly, we decided to visit and obtain records from every 5km square in Essex. The
interpretation of dot distribution maps is always open to question. A dot on any map, be
it on a 10km, 5km, 2km or 1km square basis, may represent only one individual sighting
or, conversely, many sightings of the particular species in question. However, providing
sufficient field work has been completed the maps should make it possible to assess at
least the spread of an insect and at best yield a crude indication of its abundance. The
lkm maps shown in this publication, will not correlate exactly with the species number of
records as shown in Table 3, as these figures include, in some cases, more than one
record for an individual 1km square.
Certainly, this survey has not been as comprehensive as one would have liked, but the
two criteria mentioned above have both been met. This has ensured that the limited
number of recorders have spread their efforts around the County, avoiding serious
distortions in the data. Inevitably though, the maps, to some extent, record the presence
of recorders rather than insects.
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