UKMoths 
32.04 BF671
Depressaria ultimella
Stainton, 1849
Wingspan 16-21 mm.
A fairly common species in much of England, also occurring in Wales and southern Ireland.
The adults are similar to D. daucella but the larval stages are quite different.
The flight period is from August, overwintering and reappearing the following spring.
The main larval foodplant is fool's water-cress (Apium nodiflorum).
- Larva: (description I.F. Smith ):
Foodplant: June and July. Initially in side shoot of Apium nodiflorumwhich it browns, withers and fills with wet orange-brown frass. Later in main stem, where it makes an exit hole plugged with brown silk for emergence of the adult.
Early instar
Length: 8 mm
Head: Pitchy black.
Prothoracic shield: Transparent, tinted yellowish, showing head clearly. Divided by indistinct paler median line.
Thoracic legs: Shiny transparent yellowish.
Body: Translucent. Above spiracle level; yellowish, showing viscera indistinctly orange. Whitish yellow below spiracles.
Spiracles: Black.
Pinacula: Dark grey with fine black setal spot.
Setae: Shiny translucent greyish brown.
Anal plate: Shiny transparent tinted yellowish, showing brown when gut occupied.
Prolegs: Concolorous.Intermediate instar:
Length: 12 mm and 16 mm
Head: Burnt ochre. Capsule and frons thinly edged black. Clypeus and labrum dark brown. Stemmatal area black. Black postero-lateral mark.
Prothoracic shield: Transparent, tinted yellowish and overlaid by faint brown ochre on cuticle. Divided by clear median line showing colour of body or head below. Posterior thinly edged grey-brown.
Thoracic legs: Shiny transparent yellowish.
Body: Translucent. Above spiracle level; olive-yellow, showing reddish brown viscera indistinctly. Whitish yellow below spiracles.
Spiracles: Black.
Pinacula: Dark grey with fine black setal spot.
Setae: Shiny translucent greyish brown.
Anal plate: Shiny transparent tinted yellowish, showing brown when gut occupied.
Prolegs: Concolorous. Crochets reddish brown.Late instar:
Length: 17 mm
Head: Raw umber with darker brown dorso-laterally and on frons and mouth parts. Stemmatal area black. Black postero-lateral mark. Posterior of capsule thinly edged black.
Prothoracic shield: Transparent shiny light brown. Divided by clear median line showing colour of body or head below. Posterior thinly edged darker brown.
Thoracic legs: Shiny transparent light brown.
Body: Ventrally, translucent whitish green. Dorsally greyish green with viscera showing as indistinct darker dorsal line.
Spiracles: Black.
Pinacula: Dark grey with fine black setal spot.
Setae: Translucent grey.
Anal plate: Shiny transparent showing green through thinly coloured olive-brown cuticle.
Prolegs: Concolorous. Crochets reddish brown.
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