September Thorn
Ennomos erosaria
This record describes Ennomos erosaria (species). Recorded family: Geometridae. Recorded order: Lepidoptera.
Identification and Appearance
Wingspan 30 to 35mm. Pale yellow with dark cross lines. Although superficially similar to several other of the autumn-feeding 'Thorns', this species is generally much plainer in appearance. It is very similar to the August Thorn. Perhaps the easiest way to distinguish them is that the September Thorn has all-yellow legs whilst the August Thorn has 'knee socks' where the lower part of the legs is whitish. The August Thorn also has the line nearest the base of the wing acutely angled at the costa whilst this is almost straight in the September Thorn. July to October is the main flight period, when the species is often attracted to light. The caterpillar closely resembles a small twig, and feeds on oak, birch or lime. It is reasonably common in England and Wales, becoming scarcer in the north of England and Scotland, and is rare in Ireland. In a recent survey to determine the status of all macro moths in Britain this species was classified as common.
Classification
- Kingdom
- Animalia
- Phylum
- Arthropoda
- Class
- Insecta
- Order
- Lepidoptera
- Family
- Geometridae
- Genus
- Ennomos
Imported taxonomy record. Source availability varies; see the source references and editorial policy below.
Habitat and Range
Habitat
Well wooded areas.
Seasonal Activity
July to October is the main flight period, when the species is often attracted to light.
Diet and Behavior
Life History
The caterpillar closely resembles a small twig, and feeds on oak, birch or lime.
Additional species information
Recorded status
It is reasonably common in England and Wales, becoming scarcer in the north of England and Scotland, and is rare in Ireland. In a recent survey to determine the status of all macro moths in Britain this species was classified as common.
About Butterflies and Moths: the wider group
Order-level background for Lepidoptera, the group containing Ennomos erosaria. Species-specific details appear above.
Group overview
Lepidoptera includes approximately 180,000 described species of butterflies and moths. Moths outnumber butterflies roughly 10:1. The monarch butterfly's eastern population has declined by more than 80% since the mid-1990s, and the western population by over 95% since the 1980s. The IUCN lists the migratory monarch as Vulnerable.
Ecological role of the group
Butterflies and moths are essential indicators of ecosystem health. As caterpillars, they are a primary food source for birds - a single nest of blue tit chicks requires ~10,000 caterpillars. Adult moths pollinate many night-blooming plants.
Economic and practical significance of the group
Lepidoptera are critical pollinators. In Europe, grassland butterfly species have declined by almost 50% since the early 1990s. In the UK, three-quarters of butterflies are in decline. In the U.S., five butterfly species have gone extinct since 1950, with 29 listed as endangered.
Recorded sources for this group: IUCN Red List, Xerces Society, USFWS, PNAS, WWF. Imported estimates may describe particular regions or reporting periods.
Photos of September Thorn (7)
Frequently Asked Questions About September Thorn
What is September Thorn?
September Thorn (Ennomos erosaria) is a species in the family Geometridae, within the order Lepidoptera.
Where is September Thorn found?
Habitat: Well wooded areas.
When is September Thorn active?
September Thorn: seasonal activity - July to October is the main flight period, when the species is often attracted to light..
What is the life cycle of a September Thorn?
The caterpillar closely resembles a small twig, and feeds on oak, birch or lime.