LYCAENIDAE | Polyommatinae | Polyommatini

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61.014 Plebejus argus (Silver-studded Blue)

ws: 26-32mm; Jul-Aug on heathland, Jun-Jul on calcareous grassland; heathers (Calluna vulgaris, Erica spp), gorse (Ulex spp) on heathland, common bird’s-foot trefoil (Lotus corniculatus) on calcareous grassland; common in lowland heaths of S.England and East Anglia and calcareous grassland of N.Wales.

Plebejus argus (Silver-studded Blue) §1 male

ID: The ‘silver studs’ that give this species its English name and which distinguish it from its congeners are not always easy to see. They occur on the hindwing underside as silvery-blue centres to a subterminal row of interneural black spots and are present in both sexes. Immediately proximal to each of these black spots is an orange crescent. Males have blue uppersides with a broad black margin and clear white fringes. Celastrina argeolus (Holly Blue) has a similar upperside but lacks orange spots on the underside. Male Polyommatus icarus (Common Blue) has a thinner black border on the upperside and a black spot in the basal half of the forewing underside (lacking in P.argus). Females have brown uppersides usually tinged blue basally.

Dissection

Male genitalia

§1 New Forest, Hampshire; 27/06/2008; male
§2 New Forest, Hampshire; 27/06/2008; female
§3 Stoborough Heath, Dorset; 05/07/2016; male
§4 Stoborough Heath, Dorset; 05/07/2016; female
§5 Stoborough Heath, Dorset; 05/07/2016; male
§6 Stoborough Heath, Dorset; 05/07/2016; female
§7 Stoborough Heath, Dorset; 05/07/2016; female
§8 Stoborough Heath, Dorset; 05/07/2016; female; fw 14.3mm
§9 Stoborough Heath, Dorset; 05/07/2016; male; fw 12.8mm
All images © Chris Lewis

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Page published 18/07/2014 (§1-2) | §3-9 added 09/12/2016