Barred Tooth-striped (Trichopteryx polycommata)

Barred Tooth-striped moth
Barred Tooth-striped (Alan Skeates)

The information below is designed to encourage you to look for Barred Tooth-striped in Scotland it includes an interactive map, details on the moth's life-cycle, identification and recording, as well as the use of pheromones and how to get involved.

We are concerned that this rare moth faces severe threats from Ash dieback (chalara) hence we need your help to determine its current status and better understand its habitat requirements.  We also believe it is under recorded and thus new colonies await discovery. 

If you are interested in getting involved and want more information simply get in touch.

A UK Barred Tooth-striped factsheet is also available.

 

 

Conservation Status

A former UKBAP Priority species, included on the Scottish Biodiversity List and designated an HB species in our Scottish Conservation Strategy.  

Scottish Distribution

Barred Tooth-striped is a nationally scarce species in the UK being recorded in 57 10km squares between 2000 and 2016.  Of these 19 were in Scotland where the population is centred on the Great Glen, north Argyll and Mull and the Small Isles, with one outlier in Dumfries and Galloway not far from Thornhill.

Habitat and Caterpillar Foodplant

In England Barred Tooth-striped, is found in woodland clearings and rides where it is associated with Wild Privet.  However, Wild Privet does not occur in Scotland and its main foodplant is believed to be Ash.  In the north of England some of the Barred Tooth-striped colonies are also associated with Ash.

There are several references to the caterpillars favouring scrubby Ash, however, there appears to be no direct evidence for this and it simply reflects the stature of Wild Privet and assumptions that it must therefore favour Ash of a similar height.  Larvae have only been found in Scotland in June 2006 when they were beaten from semi-mature roadside Ash trees, whilst adults have been found to be common in the vicinity of mature trees, thus further questioning the sole requirement for scrubby Ash.

Life Cycle

Adults are usually on the wing in Scotland from mid-April to mid-May which is around a month later than those south of the Border.  However, the flight period is very dependent on the seasonality of the year with adults being recorded in Scotland as early as 6th April and as late as 28th May.

Caterpillars emerge in May and June and feed into July before overwintering as pupae in a cocoon just below the ground.  The only caterpillars to be found in the wild in Scotland were recorded on 18th and 26th June.

Barred Tooth-striped larva
Barred Tooth-striped caterpillar (Mark Parsons)

Identification

The adult moth is unmistakable with a distinctive brown angled and forked central cross band.  But beware, because in Scotland some forms of the very common Early Tooth-striped, which is widespread, associated with Birch and on the wing at the same time, can possess a very strong dark cross band.  However, the band on Early Tooth-striped is never brown but is always brown in Barred Tooth-striped.  If in doubt take a photograph.

Early Tooth-striped (banded form)
Early Tooth-striped (heavily banded form) (Roy Leverton)

The dark green looper caterpillars have a pale creamy yellow stripe along their flanks and are thus very similar to those of Early Tooth-striped so need to be reared through for confirmation.

Recording

The recommended methodology south of the border is to search for adults at dusk using a torch as the moth flies around its foodplant and adults only come infrequently to light and often in small numbers. This technique is less suited to Scotland. However, it has been found that Barred Tooth-striped is attracted to light, both actinic and mercury vapour, but that the moth rarely enters moth traps, often falling short onto surrounding lit surfaces e.g. white sheets, tree trunks, outer sides of the trap etc. They also tend to come into the traps quite late at night probably after 11.30pm and continue flying through the night possibly with a flurry of further activity at dawn. Traps should be located close to Ash trees as the adults probably do not stray far.

Canterbury Christ Church University has developed a pheromone lure for the Barred Tooth-striped which has been trialled particularly successfully in North Lancashire, Cumbria and Yorkshire. The lures are used in conjunction with a pheromone trap and hung around 1 metre above the ground and left out overnight. The traps are checked early the following morning and the moths released unharmed. (NB: The pheromone lures need to be kept in a fridge or freezer when not in use).

Caterpillars can be beaten from Ash in June but often only the very lowest branches are accessible so this may not be suitable at all sites and any found should be reared through for confirmation. The great advantage of finding caterpillars is that it provides valuable information about the moth’s breeding habitat.

Scottish Distribution Map

The Google map below shows all Scottish Barred Tooth-striped records at 1km resolution or higher. If you zoom in and then hover over a marker, information on that record will appear in a box. It is also possible to navigate to different parts of the country and change the background map from aerial to terrain.

The map shows records in three age categories:

  • Green – 2010 to 2016
  • Blue – 2000 to 2009
  • Red – up to 1999

The records are in layers with the more recent records overlaid on top of older records, therefore, sites where Barred-tooth Stripe has not been recorded since 2010 should be more apparent.

Action – we need your help

Please use the map above to help target recording through light trapping, pheromone luring and/or looking for caterpillars, where Barred Tooth-striped has not been seen since 2010, or entirely new sites where you know there is Ash. To aid this we can send you a link to a map showing the distribution of Ash in Scotland taken from the Native Woodland of Scotland Survey (NWSS).

We can also supply pheromones and possibly a pheromone trap, though it is also possible to make a homemade pheromone trap from fizzy drink bottles.

If you are interested in getting involved and want more information including a link to the Ash Map, pheromones, pheromone traps homemade or purpose built, etc simply get in touch