IdentificationHints

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.