which can be determined with certainty in the field, thereby excluding some of
the Macrolepidoptera and most of the Microlepidoptera. Recently certain light-
traps have been operated, but only at one or two locations and, in most in-
stances, only for part of the summer. There is little evidence of recent fieldwork.
The neglect of the Forest by lepidopterists is shown by the following
figures: of the total number of Lepidoptera ever recorded from Essex, 89.4%
have been noted since 1950, whereas the equivalent percentage for Epping
Forest records is only 50.5%. This dramatically low figure for the Forest is
attributable to four causes:
(1) The apathy of lepidopterists to which 1 have referred and, in particular,
their neglect of fieldwork.
(2) Failure of lepidopterists to record all the species they have observed.
(3) Natural changes in species distribution. Doubleday (1836) wrote of the
Forest "The number of insects is increased or diminished by causes which
seem to defy all our attempts at discovering them. Species vanish from
spots where they have abounded, and we know not why: no change per-
ceptible to us has taken place in any of the peculiarities of the spot, but its
old inhabitants are gone. The hand of man cannot have exterminated them
. . . ". The same is true today. In the case of some prolific species, con-
stant numbers are maintained if less than 1% of the ova laid yield adults
which reproduce their kind. This being the case, a very small additional
cause of mortality may be fatal to species survival.
(4) Pollution, which has possibly taken a higher toll from Epping than from
the county as a whole.
It is impossible to quantify the influence of these causes, but I have arranged
them in what, in my personal judgement, is their order of importance. I rejected
a possible fifth cause, namely bad forestry management, through lack of
evidence that this is in any way worse for Lepidoptera now than it was in the
nineteenth century.
Epping Forest is not a good locality for Lepidoptera and this applies
particularly to the butterflies. Doubleday (1836) wrote, "The Entomology of
this part differs chiefly from that of the rest of our neighbourhood, in offering
fewer both of species and individuals." The total population today is probably
not much smaller than it was a hundred years ago, though there have been
changes in the component species. People read consolidated lists comprising all
the species ever recorded, and mistakenly suppose that they were once all to be
found simultaneously: this is far from the case. The number of
Macrolepidoptera (omitting the Hypeninae) recorded from the Forest between
1950 and 1977 is 289. It is less realistic to compare this figure with the grand
total of 538 than with the 373 recorded by the Doubleday brothers from their
boyhood up to 1835; the deficit of 84 species would probably soon be made up if
we had field-workers as energetic as the Doubledays. One does not have to
search far in the early entomological literature to discover that collectors have
always lamented the decline in insect population: things are never what they
were. Certain species do indeed become extinct: their place is taken by
newcomers and the overall population remains fairly constant.
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