Identification Feature:
Riband Wave and Plain Wave
The Riband Wave is a widespread
and common species in Lancashire, whereas the Plain Wave is very local and uncommon
and is prone to mis-identification. The problem in separating the two occurs
primarily because of the features used to identify the two moths in modern popular
identification guides. Both Skinner and Waring refer to Plain Wave being slightly
smaller, having a slightly siilky appearance to the wing and the way the outer dark
brown line on the forewing meets the leading edge.
There is quite a large overlap
in the size of these moths and therefore it cannot always be used to separate the
two species. The silkiness can be seen in most fresh specimens of Plain Wave,
but once Riband Wave is worn this can be problematic. In most cases, the Riband
Wave has a inward kink at the top of the outer line on the forewing but several
Riband Wave have been found in Lancashire which have had a smooth gently curving
line resembling Plain Wave (determined by dissection).
Colin Barnes has photographed
both of these moths during 2008 and one further feature (as long as the moth is
not too worn) can be demonstrated well in his photos attached to this feature.
On the edge of the forewing and hindwings of these two moths are a series of long
dashes - in Riband Wave these are separated by dots. This feature does not
occur in Plain Wave. Using the published identification features in Skinner
or Waring plus this additional fairly widely known, but not widely published feature,
it should be possible name your large Wave species
Plain Wave
Riband Wave
Early Tooth-striped / Mottled Grey
The text books suggest there should be no problem separating
this pair of moths and when a recorder is familiar with both and encounters them
regularly that is probably the case.
However for those of us who rarely see either of these species or see them for the
first time, they can be problematic.
Early Tooth-striped
Flight period:
The national identification guides (Skinner and more recently
Waring) give the flight period as April and May. Records in
Lancashire
in recent years indicates this to be reasonably accurate, although confirmed records
from late March are not unknown in lowland areas.
Generally, Mottled Greys are beginning to look rather worn by the time
Early Tooth-striped appears. There
are very few records of Early Tooth-striped after the first two weeks of May.
Identification:
The Early Tooth-striped (ETS) is a very variable species,
with the forewing background colour ranging
from off-whitish to mid-grey, occasionally with a brownish
tinge. Fresh specimens can have a lichen
green sheen in the greyer coloured moths.
By contrast the forewing of Mottled Grey (a definite misnomer) is pale straw
coloured with slightly variable darker brownish spots and markings, a colour combination
not seen in ETS.
MG also has a shiny look to the forewing in fresh specimens.
The leading edge of the forewing in ETS is gently rounded (think of the shape
of November Moth), whereas in Mottled Grey (MG) it is almost straight giving
the moth a more triangular look, particularly in the smaller female.
Both male and female ETS have simple antennae whereas in MG, the male’s antennae
are quite feathery (see below).
 |
Left: Mottled Grey (male) antennae
Right: Early Tooth-striped (male and female) antennae |
 |
Mottled
Grey has a very spotted, dotty appearance to the forewing (even on the cross lines)
whereas ETS, in all its variable forms, lacks these scattered dots.
ETS has either distinct bands of darker colouring, specific blackish thin angled
lines or a quite clean pale appearance.
The hindwings of male ETS are white with a darker edging and have a distinct small
alula (extra flap of membrane) near the base of the wing - this feature cannot easily
be seen in live moths. The hindwings
of MG are proportionately longer than those in ETS leading them to protrude slightly
when at rest on occasions. As this feature is
not always obvious, due to differing resting postures,
the lack of a protruding hindwing should not be used to identify the moth
as ETS. Conversely, it does
allow positive identification of MG if present.
 |
Early Tooth- striped
Four specimens depicting the range of variation in markings.
Note curved edge to forewings. |
Distribution:
The distribution of the two species in
Lancashire
is fairly similar although MG is perhaps a little less widespread.
Whether this is genuine or not or purely due to the early emergence and therefore
less frequent trapping of the species is unknown.
There seem to be quite big swathes of the county where both species are absent,
particularly in more open lowland areas and in towns.
If scrubby or non-amenity planted woodland is nearby however then both moths
will usually be found. Both species
occur locally or more frequently in the higher more open parts of the county.
Mottled
Grey
Flight period:
The text books give the flight period as March and April
but in
Lancashire
in recent years, occasional records have occured in mid February.
There have also been records into early May at some upland sites
so flight period alone should not be used as an indicator of species.
Looking back to records from the 1960s, Mottled Grey was regularly encountered
well into
late April.
Identification:
See under Early Tooth-striped.
 |
Mottled Grey
Male above Female below.
Note the long hindwings and speckled appearance. |
Distribution:
See under Early Tooth-striped
I would like to thank Chris Darbyshire, Kevin McCabe,
Bill Aspin, John
Girdley and
Pete Marsh for comments on the identification of these two species which have been
incorporated into the above text. Also
thanks are due to Colin Barnes and Eddie Langrish for retaining moths for photography
or providing photographs for this article.