Netted carpet moth (Eustroma reticulatum)

KingdomAnimalia
PhylumArthropoda
ClassInsecta
OrderLepidoptera
FamilyGeometridae
GenusEustroma (1)
SizeWingspan: 24-28 mm (1)

Classified as Vulnerable in Great Britain (2).

The forewings of the Netted Carpet moth are dark brown and are criss-crossed with a network of pale lines, from which both the common and specific names are derived (reticulatum derives from the Latin reticulum, meaning 'small net'). The caterpillar reaches 2.5 cm in length, and is pale green in colour with a broken red-brown line running along the centre of the back (3).

This moth is localised in its distribution throughout Europe. In the UK it is known only from Cumbria where there are currently 8 colony groups. The populations undergo substantial fluctuations, mirroring the fortunes of the foodplant of the caterpillars, and there has been an overall decline since 1980 (4).

In the wild the caterpillars feed only on touch-me-not balsam (Impatiens noli-tangere), itself a Nationally Scarce species. This annual plant is found in damp, open woodland where it favours streamsides, moist shady road verges and sites of temporary disturbance (4).

Adults of this single-brooded species are most often seen flying around the foodplant between early June and mid-August (1). The eggs are laid singly on the undersides of the leaves of the balsam (3). The caterpillars are present in August and September (1) initially feeding on leaves, and then progressing to flowers and seedpods. Pupation over the winter takes place in moist soil (4).

In many cases, the decline appears to be due to lack of disturbance factors in or near foodplant colonies, leading to their eventual loss. Changes to drainage and roadside maintenance have also had an effect in places (4).

This species has been targeted as a priority for conservation action under the UK Biodiversity Action Plan (UK BAP). Since 1994, it has been the subject of a Species Recovery Programme run in partnership by English Nature, The National Trust, Butterfly Conservation, and Reading University. The Species Action Plan aims to increase the range and size of the populations of this moth (2).

Further reading on moths:
Skinner, B. (1998) Colour Identification Guide to Moths of the British Isles. Viking Press, London.
Leverton, R. (2001) Enjoying Moths. Poyser, London.

Information authenticated by The National Trust.
http://www.nationaltrust.org.uk/main/

  1. Skinner, B. (1984) Colour Identification Guide to Moths of the British Isles. Viking Press, London.
  2. UK BAP (Dec 2002): http://www.ukbap.org.uk
  3. Carter, D.J. and Hargreaves, B. (1986) A field guide to caterpillars of butterflies and moths in Britain and Europe. Collins, London.
  4. Hooson, John. National Trust. Pers. comm.