35.031 Helcystogramma rufescens (Haworth, 1828)

Status and Distribution

Widespread and locally common throughout much of England, Ireland and the Channel Islands. More local in northern England, Wales and Northern Ireland while in Scotland it appears to be restricted to a few sites in south-west and western Scotland and a single record from the Outer Hebrides. Apparently absent from the Isle of Man.

National Status: 

Common

Bradley & Fletcher no: 

868
Photo courtesy of UK Moths.
Photographer: Charles Baker
Location: Heath & Reach, Bedfordshire

Provisional Map

Maps updated with all data received by February 2018.

    Imago

    Helcystogramma rufescens (Photo: B Smart)  Helcystogramma rufescens bred (Photo: B Smart)

    Larva

    Helcystogramma rufescens early instar (Photo: B Smart)  Helcystogramma rufescens larva (Photo: B Smart)  Helcystogramma rufescens larvae (Photo: B Smart)  Helcystogramma rufescens larva (Photo: B Smart)  Helcystogramma rufescens larva (Photo: B Smart)  Helcystogramma rufescens larva (Photo: B Smart)  Helcystogramma rufescens larva Lancs 2017 (Photo: B Smart)

    Pupa

    Helcystogramma rufescens pupa (Photo: B Smart)

    Set Specimens

    Helcystogramma rufescens (Photo: S Palmer)

    Dissection Group

    Foodplant and Larval Feeding Signs

    Helcystogramma rufescens feeding sign on grass (Photo: B Smart) Helcystogramma rufescens feeding sign (Photo: B Smart) Helcystogramma rufescens feeding (Photo: B Smart)  Helcystogramma rufescens spinning Lancs 2017 (Photo: B Smart)

     Arrhenatherum elatius (false oat-grass), Poa spp. (meadow grasses), Dactylis glomerata (cock's-foot grass), Brachypodium sylvaticum (false brome), B. pinnatum (tor-grass), Calamagrostis epigejos (wood small-reed), Schedonorus (Festuca) arundinaceus (tall fescue) and a Milium sp (millet).

    Foodplant Map

    Habitat

    Rank, often ungrazed or lightly grazed grassland on downland, coastal areas, roadside verges, damp fields, canal banks and woodland rides.

    Finding the Moth

    Larva: spins the grass blade into a roll, open at each end, changing rolls several times before pupation. Fenestrates the leaf from within often causing the tip of the grass blade to appear white.

    Adult: can be disturbed during the day and is attracted to light.

    Similar Species

    In the past, the separation of this species from H. lutatella was based on the presence or absence of blackish stigmata on the forewing. This was proved to be unreliable by Heckford and Sterling (1999) and subsequent examination of Museum specimens from various localities demonstrate that some H. rufescens can have between one to three dark brown scales in the middle of the forewing at one-third and two-thirds.

    Heckford and Sterling gave the key identification features as follows:

    H. lutatella - the forewings are grey-brown to brown coloured and lack the ochreous coloured veins of H. rufescens. The labial palps are white above and below (without brown scales) and the hindwing of the female pale to dark grey.

    In H. rufescens the forewing is ochreous (or veins ochreous with brown scaling), the outer margins of the labial palpus has brown scales and the hindwing of the female is whitish.

    Separating the larva of these two species is more readily achieved in early instars. In H. lutatella, the abdominal segments one and two are black with a reddish or reddish brown sclerotized plate on each anteriorly, smaller on segment one, confined to the dorsum and rounded with small lateral extensions. In H. rufescens, these two segments are black with the sclerotized plates dark olive (early instar) becoming pale brown in later instars. The plate on segment one is very small consisting of a narrow, linear band, hardly broadening about the dorsum.

    Microscopic examination of small, pale, worn specimens is recommended in extreme southern coastal areas where the shape of the sclerite of tergite 1 and 2 in both sexes are distinctly horse-shoe shaped in H. rufescens and boomerang shaped in H. lutatella (see link to the genitalia in the Images section above). Only differences in the female genitalia are of any practical use in separating the two species (Heckford and Sterling, 1999, full reference in the Publications: Published Papers section of this site).

    Larval Occurrence

    Larval Occurrence

    Flight Period

    Flight Period

    Single brooded from mid-June to late August with occasional, possible second brood moths from September to early October.