Langmaid's Yellow Underwing

 Langmaid's Yellow Underwing moth

Image from Upper Thames Moths

The Lesser Broad-bordered Yellow Underwing Noctua janthe, Langmaid’s Yellow Underwing Noctua janthina and Wilson’s Yellow Underwing Noctua tertia

Noctua janthe, janthina and tertia in Britain.

The Lesser Broad-bordered Yellow Underwing Noctua janthe is a common moth in Berkshire (VC22). Many moth recorders in Berkshire are in the habit of recording any similar-looking Noctuid moth as Lesser Broad-bordered Yellow Underwing (agg.) janthe/janthina or more recently as Lesser Broad-bordered Yellow Underwing (agg.) janthe/janthina/tertia (e.g. on iRecord).

However, on 9 July 2001, a very similar-looking Noctuid moth taken at Southsea, Hampshire was identified as Noctua janthina [Denis & Schiffermüller], 1775. This individual, recorded by John Langmaid represented the first recorded example in Britain.

Since then, Langmaid’s Yellow Underwing, as it became known in the UK, has been recorded in other locations across the UK, including in Berkshire, where the first specimen was recorded by Finlay Hutchingson in [year].

N. janthe and N. janthina are (arguably) two species of a three-species complex, the third species being N. tertia. The first record for Britain was collected in Kent in 1992, but it was not confirmed to be Noctua tertia until 2014. Subsequently, some authorities have disputed that N. tertia is a separate species.

Checking for N. janthina in my garden in Earley, Berkshire (VC22)

During 2025 a selection of potential N. janthina moths, from the many N. janthe/janthina agg. moths taken at light in Earley, Berkshire, were retained throughout the flight season. The specimens from the early part of the season were placed in a freezer for later inspection. In October, when there appeared to be evidence of migration and many N. janthe/janthina moths were again appearing in the trap, a small sample was taken. While still in individual pots, four of the moths produced eggs. These were retained with the intention of rearing any resultant caterpillars.

Identifying the potential Noctua janthina

Each moth selected to be sampled was inspected visually using hindwing upper-side and forewing underside features as described and illustrated on various websites.

Those that appeared to be good candidates for N. janthina were either frozen and retained or, in the case of the females in October, retained until they had laid an egg batch shortly after which they died.

Each adult female moth and her egg batch were labelled and carefully kept separate from the other moths and egg batches to prevent any accidental confusion.

Each moth was assigned an identifying letter A – L as shown in the table below.

Table of specimens

Identifier	Date of capture	Location	Sex	Method	Notes
A	2/10/25	Earley	F	MV light (e.g.)	Hatched night of 12th/morning of 13th October 2025
B	2/10/25	Earley	F		Hatched night of 13th/morning of 14th October 2025
C	2/10/25	Earley	F		Hatched night of 13th/morning of 14th October 2025
D	3/10/25	Earley	F	125W MV	Hatched night of 14th/morning of 15th October 2025
E	7/10/25	Earley		125W MV
F	Early in season	Earley			Frozen
G	08/08/25	Billingbear Farm		125W MV	Frozen
H	Early in season	Earley			Frozen
I	Early in season	Earley			Frozen
J	Early in season	Earley			Frozen
K	Early in season	Earley			Frozen
L	Early in season	Earley

 

 

13/10/2025.

Group A: Newly hatched larvae were observed on the morning of 13/10/25. These amy have hatched overnight. The tube containing the dead moth, eggs and newly hatched larvae was placed in a tub with grass, hawthorn, blackthorn, dandelion and sallow. A dandelion leaf was placed halfway into the glass tube.

 

 

 

 

 

14/10/2025.

Group A: Very few of the larvae have left the glass tube. I removed the dandelion leaf which had a few larvae on it and pushed a bit of the hawthorn into the glass tube.

Group B: Newly hatched larvae were observed on the morning of 14/10/25

Group C: Newly hatched larvae were observed on the morning of 14/10/25.

 

15/10/2025

The Group D egg batch has hatched, again either over night or early this morning.

Moved to put with dandelion, grass and clover.

 

18/10/2025 - UPDATE

I have now counted the tiny caterpillars and I have over 350 as follows.

Identifier	Number of larvae
A	60+
B	125
C	56
D	110

 

 

I tried to ascertain if the caterpillars are showing a preference to a particular foodplant. The following have been eaten/nibbled.

·         Dandelion

·         Dock

·         Grass

·         Clover

·         Sallow

·         Blackthorn (barely)

·         Hawthorn (barely)

I suspect that it is more the condition of the foodplant than the species which is influencing their choice. Where I saw the grass had been grazed was where it had turned yellow. There were more caterpillars on the softer material. The largest number of caterpillars were to be found within very damp rotting brown-to-black leaf material within a fold of a leaf or where two leaves had lain one upon another. This enclosed space was filled with their droppings, and they appeared content to live in this very damp and frass-filled environment. I have not found any dead or sickly-looking caterpillars so far.

19/10/2025

I added shop-bought organic lettuce and spinach to the mix of foodplant offered as I know these to wilt quite quickly. I’m interested to see if they choose either of these options.

27/10/2025

I got busy and neglected the larvae for a period. When I checked them today, some of the foodplant had gone brown and liquid and I was very concerned to see if the larvae had survived.

I cleaned out each pot, one pot at a time. I emptied the whole contents of the first pot onto kitchen paper and cleaned and prepared the empty pot for rehousing them. Initially, many of the larvae appeared to be dead, however after a period, some of them stated to move. Using a small soft paintbrush and a teaspoon, I transferred each larvae that I saw hurriedly heading off in various directions. Many larva that appeared at first glance to be dead, surprised me by waiting a long time and then suddenly springing into action and making a run for it.

I noted that the spinach had not been eaten other than a few small patches, whereas the lettuce pieces had been nearly skeletonised. Larvae mostly seemed to favour pieces of grass, especially those that had gone yellow.

I put in a fresh piece of lettuce and some grass, both wide-bladed green and yellowing, plus a very fine green grass.

Once I had transferred sufficient batch A larvae to pot A, I removed all of the old foodplant, kitchen paper and remaining larvae and released them to a suitable patch of the garden.

I repeated this process for each larval batch (A, B, C and D)

06/02/2026

My last entry was on 27/10/2025. Some time has passed and I believe I have made some notes in a Word document to cover that period.

Status today.

A

B

C

D