Introduction
 In
Britain approximately 2500 species of Lepidoptera have been recorded,
all but around 50 of which are moths. To acquire a thorough knowledge
of all the species requires time, enthusiasm and dedication – but
don’t be put off, above all have fun. The following pages provide
an insight into various recording techniques, rather than a guide to identification.
When to Look
Most species of butterfly and moth are on the wing, i.e. in their adult
form, between March and October, although the period from mid-May to late
August is perhaps the best time to undertake survey work. It should however
be noted that some species only fly in the early part of the season, so
survey work for them should be concentrated in May and June. Ova, pupa
and larva can all be found at any time of the year.
Recording Methods
Recording Lepidoptera can take a number of forms; at its simplest noting
the identity and number of species seen during a visit to a particular
site, at its more complex the use of light traps to attract moths overnight
and later identifying the species caught. This latter can also be combined
with wine roping!
Transect Routes
This is also known as the Pollard Walk and is used to assess changes
in the abundance of butterflies from year to year. A route is chosen that
goes through representative habitats within the site and mapped on a habitat
map top ensure that an accurate record of the route is kept for future
transect walkers.
The transect is walked at a uniform rate and all butterflies seen 5 metres
either side of the route and 5 metres in front are noted and the figures
transferred to a recording form. Ova, pupa and larva should also be noted
if located. The walk is repeated once a week between April and September,
but not necessarily at weekly intervals. Certain criteria need to be met
to ensure that the walks are conducted in similar, suitable weather conditions:
- Visits should commence after 10.45 and finish before 15.45.
- The weather conditions must satisfy minimum requirements:
- The temperature must be above 13°C
- If the temperature is between 13°C and 17°C there must be
at least 60% sunshine
- If the temperature is over 17°C, then it can be either sunny
or cloudy.
Netting
In some instances it may be necessary to net a moth or butterfly to confirm
the identity, especially when just starting to learn the differences,
but with field experience the need to net becomes less. Sweep netting
involves the use of a stout canvas bag mounted on a sturdy metal or wooden
frame, swept back and forth through vegetation to dislodge insects from
their resting-place. Lighter aluminium butterfly nets should be used for
catching insects on the wing.
Wine Roping
Prior to the introduction of moth traps black treacle, sugar, wine or
stout (or a combination) was used to soak ropes that were then strung
out or draped over tree branches or fences to attract moths. This method
is not commonly used today, a light traps are far more effective.
Light Traps
These take various forms, however they all follow the same basic construction.
A light in the UV or MV range is used to attract moths to a collecting
box containing egg trays. The moths can then be identified later that
night or the following morning and released. The most popular types are
the 12v actinic heath traps and the more expensive mains voltage MV Skinner
or Robinson traps. The latter two require a 240v power supply but attract
a larger number of species and moths than the more portable Heath Traps.
Prices are around £50-00 for a Heath Trap, £100-200 for a
Skinner trap and £400 for a Robinson. However with a little electrical
know how one can be built for a smaller outlay. To
buy a moth trap, click here
Photographing
A good close-up photograph / slide can be useful for identification purposes,
providing the diagnostic features are clearly visible. A 35mm camera with
a close-up lens is necessary obtain a good shot.
Collecting
This is not necessary for larger more obvious specimens, however a species
new for a county normally requires a voucher specimen – consult
your county recorder first. If you should come across a new species for
the county, take a description and try to have an independent observer
confirm your record - take a photo if possible. |
