Fern

Horisme tersata (Denis & Schiffermüller, 1775)

This light brown moth rests, like many other members of the Geometridae family, with its wings flat against the substrate it rests upon. Several faint crosslines cross the wings, with one particularly dark crossline. The similar Cryptic Fern (H. radicaria) has recently been discovered in the UK, which stronger pale markings, but require dissection to be certain of identification. The larvae are twig mimics, with a slender, elongate larvae, light brown in colour, with black streaks running down the body.

Identification

This light brown moth rests, like many other members of the Geometridae family, with its wings flat against the substrate it rests upon. Several faint crosslines cross the wings, with one particularly dark crossline. The similar Cryptic Fern (H. radicaria) has recently been discovered in the UK, which stronger pale markings, but require dissection to be certain of identification. The larvae are twig mimics, with a slender, elongate larvae, light brown in colour, with black streaks running down the body.

ORDER

Lepidoptera

FAMILY

Geometridae

TYPE

Moths

In Britain this species is restricted to southern England and southern Wales, being more widespread in the east. In Dorset, the Fern is most frequent in north and coastal Dorset, while in Somerset it is widespread but thinly distributed. At Wyke Farm the Fern is fairly regularly recorded, and is likely breeding here.

The Fern can be found where the foodplant grows in open woodlands, scrubland and hedgerows.

The larvae feed on the leaves of Traveller’s Joy.

The adults fly from May to September, peaking in July. During their flight season, they are most often observed attracted to light.

The larvae can be found between July and September, when the larvae can be found feeding at night.

MONTHS - SEASONALITY
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
LATIN NAME

Horisme tersata

Size (MM)

Wingspan 31-36 mm

iucn Status
lc

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