Logo Phegea Butterflies in the Benelux
Frits Bink & Rosita Moenen 2015

Based on: Dagvlinders in de Benelux 2013
Revised and extended
Edited by Sylvain Cuvelier & Peter Russell

Vlaamse Vereniging voor Entomologie
VVE Werkgroep Dagvlinders

Flemish Entomological Society
VVE Workgroup Butterflies

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50. Glaucopsyche alexis (Poda, 1761) / Green-underside blue / Lycaenidae – Polyommatinae

NL: bloemenblauwtje / D: Himmelblauer Steinkleebläuling, Großpunkt- Bläuling, Alexis-Bläuling / F: azure des cytises, l’argus bleu violet

Photographs: Frits Bink ©.

Small, wing length 15 (14-17) mm. The species occurs in the Benelux in chalk grassland and wood edges in warm sites in the south of Luxemburg and Wallonia.

Butterfly is on the wing from mid-May until late-June. The species is recorded from sub-continental and continental climates, amplitude 7 to 17. Required heat sum 600°d and maximum tolerated 1800°d, corresponding climate windows 22 and 35 weeks.

The species occurs in a low density and widely spread; it occurs also at sites where haymaking is restricted to a period late in the season.

Ecological characteristics

Behaviour over time
Overwintering: pupa in the litter layer.
oviposition starts after 4-6-days when the body contains 90 (70-114) eggs, potential production 1.3 times as much.
Larval feeding periods:
three weeks in the period from mid-May until mid-July.
Generations: one.

Spreading of risk:
repeated diapause in pupal stage.
Life cycle:
egg 4 (3-8) days; larva 22 (16-30) days; pupa about 47 weeks.
Life span of adult:
short, 2 weeks.

Photographs: Frits Bink ©.

Behaviour in space
From stay-at-home to migrant: stay-at-home, spatial requirement modest.
Finding a mate:
male patrols.
Orientation in the landscape:
gradient between forest edge and tall grass to short grass.
individually on flower buds.

Threats from other organisms: larval colouration adjusted to the colour of the flowers on which it feeds.
Myrmecophily: full array of ant-attracting and appeasing organs present and tended by ants most of the time.
Threats from the environment:
rather vulnerable, butterfly only on sheltered sites.

Feeding habits
Adult: nectar, prefers flowers which are suitable host-plants for the larvae.
feeds on flower buds and young fruits.

Larval foodplants
Plant species: Fabaceae, e.g. Astragalus glycyphyllos, Genista sagittalis, G. tinctoria, Lotus corniculatus, Medicago sativa, Onobrychis viciifolia, Securigera varia.

Rearing experiment based on specimens from Torgny, Belgium:
19 June 1983: three females captured.
23 June: one female laid ten eggs on Lotus and Medicago.
26 June: eggs hatched.
1 July: one young larva observed feeding by scratching a leaf of Onobrychis.
11 July: larvae crept down to search for a pupating place.
12 July: most larvae had disappeared, one still feeding on flowers.
18 July: girdled pupae found in litter layer in a ‘cocoon’.
Overwintered outdoors.
16 May 1984: last pupa hatched.

Table 50-1. Results of dissections

Table 50-2. Collection and observation localities

B, Torgny 237 m, 49° 30’ 40”- 5° 29’ 04”E; 20 June 1983.
D, Kaiserstuhl, Badberg 433 m, 48° 05’ 47”N – 7° 40’ 40”E; 9 July 1985.
D, Lorch 300m, 50° 02’ 05”N – 7° 47’ 56”E; 26 May 1986.
F, Montmédy 217 m, 49° 31’ 07”N – 5° 21’ 33” E; 27 June 2002.
F, Velosnes 179 m, 49° 30’ 09”N – 5° 27’ 27”E; 28 June 2002.

Fig. 50-1. Glaucopsyche alexis, phenogram adapted from Fichefet et al. 2008: 105.

Fig. 50-2. Glaucopsyche alexis, habitat characteristics.

Fig. 50-3. Glaucopsyche alexis, climate matrix, heat-sums 600 - 1800°d.

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Contact Werkgroep Dagvlinders: Jurgen Couckuyt