Broom moth decline

Evan and Carolyn reported a Broom moth (Melanchra pisi) in the earlier post, a species which was common throughout the country. In Butterfly Conservation's "The State of Britain's Larger Moths 2013" the Broom moth is reported to have declined by 84% over the last 40 years. The following graph shows the number of individuals of the Broom moth recorded per year at a single Rothamsted site in the county since 1976. Following the spike in 1995-96 their numbers declined significantly, actually reaching 0 in 2013.

None of the normal suggested causes for this would seem to apply, ie habitat change, agricultural intensification, light pollution and it seems rather sudden for climate change.

Tony

May Moths

On our return from a cold Northern England the weather improved with a minimum temperature of 10.6°C last night. Our garden trap produced 14 species of which seven were new for us this year - Pale Tussock, Spectacle, Broom Moth, Chinese Character, Pale-shouldered Brocade, White Ermine & Flame Shoulder.

Carolyn & Evan

Pale Tussock

Spectacle

 

Spectacle - Front View

Broom Moth

Barred Umber, Square Spot & Friends

Twenty nine species in total, in three traps last night at Ynys-hir.
The most numerous was eleven Brown Silver-line, six Great Prominent, three Clouded Silver and three Brimstone.The first Silver Y, Iron Prominent and Scalloped Hazel of the year from the site and three micros, Adella reaumurella, Incurvaria oehlmanniella and Syndemis musculana.
We also had two Square Spot, this species is showing an increase with only ten records up to the year 2000 and eleven records last year alone - 59 overall.
A real beauty - a fresh Barred Umber with lilac tones that do not show well on the photo.

Barred Umber

Scalloped Hazel

White-pinion Spotted - sorry about the 'blob'

Square Spot

Engrailed - for comparison

Least Black Arches

Syndemis musculana

Ina, Tony and Joe

Prays fraxinella - Ash Bud Moth

Micro-moth field tips: Prays fraxinella (22.002). Early May is the best time to look for the feeding signs of this species, as small saplings of ash may contain noticeably wilted shoots. If one looks carefully at these, frass may be seen emanating from the base of the shoot. If you break off the wilted shoot, there is a hole leading into the main twig. The larva can be seen within this, as in the second photo below (although check the larva isn't in the broken-off shoot before you've disposed of it!). Pupation occurs within a netted cocoon, either within the feeding place or elsewhere on the tree. The larva, will feed on fresh ash shoots in captivity.
There is a small uniformly dark form and DNA evidence suggests it is a seperate species Prays ruficeps (22.003). I have no knowledge of the feeding signs of the latter.
Thanks to Ben Smart for photos and information.

Feeding signs




Larva
 

 

 



 

Daytime Observations

The moth trap has not been too productive of late, a mixture of strong winds, rain and the May lull.  We have been venturing out on the odd occasion the sun put in an appearance and taken a few photographs with captions below.

Adela reaumurella

Drinker

Coleophora serratella - case on Birch

Common Heath

Micropterix calthella - large numbers feeding on Sallow blossom



Coleophora serratella - moving back into mine from case

 

Ina and Tony

Early Thorn

Four weeks ago I potted an Early Thorn outside the trap and put her in my pocket to release later somewhere safer, I hate it when I accidentally step on a moth!
My pocket then turned into a maternity ward (topical point!) and she had laid 42 eggs inside the pot.  Two weeks later the eggs hatched and were placed on Hawthorn in a large sandwich box. My 'babies' are now 2 weeks old and eating voraciously.  As I have not been able to count them I am not sure how many have survived so far - may be easier when they are bigger.
Ladbrooks are not taking bets on the names to my knowledge!

Ina

Identification Focus from Emoth - Les Hill

Identification Focus: Distinguishing Red Twin-spot Carpet (Xanthorhoe spadicearia) and Dark-barred Twin-spot Carpet (X. ferrugata)

To kick off what may become a short series of identification focus articles, I have chosen Red Twin-spot Carpet and Dark-barred Twin-spot Carpet, two species easily confused; however, once you to start to take a critical look at some of their features, they should be relatively easy to distinguish when fresh or at least give the recorder good pointers to identification.

Firstly, the ‘notch’ which may be found on the inner crossline near the leading edge adjacent to the central band is no longer considered reliable and shouldn’t be used. It can be seen from the image below that both specimens may be considered to have this notch depending on the observer’s point-of-view.

Image © Tom Tams. Northumberland Moth Group.

Well-marked spadicearia are quite distinctive, but once worn can be difficult to distinguish as features become obscured. Worn, darker-banded examples of spadicearia could be confused with the blackish-banded ferrugata form unidentaria. Conversely, the uncommon, reddish-banded typical form of ferrugata may also confuse some recorders believing it to be spadicearia. Many requests for determinations from recorders claiming ferrugata turn out to be spadicearia.

The following image by Tom Tams, Northumberland County Moth Recorder, demonstrates the feature differences in forewing upperside features. The use of a photographer’s [18%] grey card help represents the true colours and gives good moth/background contrast. However, these ground colours do vary between individuals.

Here are a few pointers to help you towards distinguishing the two species, but do bear in mind some or all of these can be subjective and may be inconclusive:

 The overall ground colour of spadicearia when fresh is generally richer and warmer reddish-brown than in ferrugata.

 The overall contrast between the central crossband and the rest of the forewing patterning is generally high in ferrugata and low in spadicearia.

 The trailing area is lighter and creamier in ferrugata and darker and greyer in spadicearia.

 The width of the central crossband in Dark-barred Twin-spot Carpet generally steps out more dramatically at one-half than in spadicearia.

 The ‘twin-spot’ is less contrasting with the ground colour in spadicearia, while in ferrugata it is isolated from any colour and high contrasting.

 The white or whitish crosslines either side of the central crossband are generally wider in spadicearia and bordered with a blackish line of similar thickness. The blackish lines are very thin to obscure in ferrugata.

 

Sometimes these species will rest with their wings held high, completely covering up the forewing upperside features. All is not lost, spadicearia usually shows some of the reddish-brown ground colour on the undersides; however, ferrugata usually show no ground colour, instead it is an almost uniform grey.

Hopefully by using some of these features, recorders will find them useful to help towards distinguishing these two species a little easier. If you do have to aggregate these two species, please don’t record them as “Twin-spot Carpet” This is another species altogether and not related.

Further reading:

Townsend, M., Clifton, J. and Goodey, B. (2010) British and Irish moths: an illustrated guide to selected difficult species www.mothscount.org/uploads/Difficult_species_guide_page_24.pdf

Townsend, M. 2010. Observations on the use of wing-markings and genitalia to distinguish Dark-barred Twin-spot Carpet Xanthorhoe ferrugata (Cl.) and Red Twin-spot Carpet X. spadicearia ([D. & S.]). (Lep.: Geometridae) and on the implications of recording these species. Entomologist’s Rec. J. Var. 122.

By Les Hill, Butterfly Conservation