17 October 2017

16 October 2017 – Turnips and Mangel-wurzles

Turnip Moth (Agrotis segetum)

I have only seen the Turnip Moth once before and that was at Bottengoms Farm (on the Suffolk / Essex border) when Ronald Blythe kindly invited me to trap in his garden.  I had hoped to be able to show him how many different species there were floating through the foliage and perhaps peering in through the windows at night.  The night was cooler than one would have wished but there were just enough species to show there were many about which he (and I) knew nothing.  One was a Turnip Moth.  The scientific name can be broken down to ‘grassland countryman’ (Agrotis) and ‘field where a crop is grown’ (segetum).  This reveals the true nature of the caterpillar which will munch through turnips and mangel-wurzles at considerable speed.

I assumed the moth photographed (above and below) at Shandy Hall was a Sword-grass as the wings seemed to enfold the thorax like chocolate.  But it didn’t look like either of the sword-grass moths that have been identified here already.  Could it be a Pearly Underwing (Peridroma saucia) ? Possibly, but that moth is not common and yet ‘may appear almost anywhere’ – according to the Field Guide.

On consulting British Moths and their Transformations Humphreys and Westwood pub. 1843 the following description was found : 

‘This variable insect measures from 1½ to nearly 2 inches in the expanse of the fore wings, which are of a brown colour, very inconstant in its hue, sometimes being nearly black, and considerably irrorated with darker shades; near the base of the wing are several indistinct  irregular darker fasciae, one of which runs more distinctly across the wing at the base of the spear-shaped stigma; the basal stigma is oval and rather small, circled with a dark line; the ear-shaped one is large and dusky, and followed by a double undulated fascia across the wing, and the margin is marked with a row of small semi-oval black spots.’ 

Turnip Moth (above)

And there (above) is what has been described so carefully.  Mr Fletcher revealed the true identity so I can be sure it is correct and that we have now recorded 425 species 

Turnip Moth (illustration)

The illustration shows (Agrotis segetum) but the name is listed as Common Dart.