Butterflies of Europe
Idas Blue
Plebejus idas  LINNAEUS, 1761
Plebejus idas, male, Hor valley, Hungary   Peter Bruce-Jones
Altogether there are about 70 Plejebus species, distributed variously across North America, Europe and temperate Asia.
The males of most species are metallic blue, while females are generally a dull earthy brown, with small orange submarginal lunules. Most species are small and delicate, and have narrow forewings. The undersides are marked with a distinctive pattern of white-ringed black spots, and the orange submarginal lunules are usually prominent, and often studded with a few reflective blue scales.
The commonest and most widely distributed species is idas which occurs in North America as well as in Europe and Asia.

Plebejus idas, male, Hor valley, Hungary   Peter Bruce-Jones
This species breeds in almost any wild grassy habitats where the larval foodplants are abundant.
The eggs are laid on the stems of Lotus corniculatus or rockrose Helianthemum chamaecistus, very close to the base of the plants. The eggs are always laid close to nests of the ant Lasius niger.
The larva develops within the egg in the late summer but doesn't hatch until the following March. It feeds by day on the flowers and tender leaf tips of the foodplants. The larva is constantly attended by the ants which milk it to obtain a sugary substance exuded from an eversible gland on its back. In return the larva gains protection because the presence of ants deters predatory wasps, spiders and carnivorous bugs.
When ready to pupate, the larva is driven or carried into the ant's nests. The pupa is attended by the ants until the butterfly is ready to emerge in late June or early July, at which time it crawls out of the nest and makes it's way up a stem where it settles to expand and dry it's wings.
Adult behaviour

Males often aggregate at the edges of puddles with other Polyommatines. Both sexes can be found in large numbers in hay meadows where they nectar a wide variety of flowers. The males flutter constantly in search of females and are easy to find but the earthy brown females are sedentary in behaviour and harder to locate. When the sexes meet, copulation takes place almost immediately, with no observable pre-nuptial ritual. Mated pairs can sometimes be found basking with wings in the characteristic three-quarters open position. They remain in copula for about an hour.

Overnight or in overcast weather conditions the butterflies roost amongst grasses or on bushes; adopting a head-downward posture. On sunny days the butterflies are active until sunset, and at certain sites can sometimes be found basking in groups of 30 or 40, congregating on bushes to soak up the last remnants of sunlight before going to roost or the night.



Contact  /  About me

Butterfly-watching holidays

Trip reports

UK latest sightings

Frequently asked questions

Strange but true !

Taxonomy & Evolution



Enemies of butterflies

Survival strategies

Migration & dispersal

Habitats - UK / Palaearctic

Habitats - Tropical rainforests

Butterfly world census

Butterflies of the World :

British Isles


Amazon & Andes

North America

temperate Asia


Indian subcontinent

Malaysia & Borneo

Papua New Guinea

Australia & N.Z.

Insects of Britain & Europe

Insects of Amazonia

Moths of the Andes

Saturniidae - Silkmoths

Caterpillars of the World

Butterfly Photography

Recommended Books



Code of practice

Copyright - text & images

Copyright - text & images






All photographs, artwork, text & website design are the property of Adrian Hoskins ( unless otherwise stated ) and are protected by Copyright. Photographs or text on this website must not be reproduced in part or in whole or published elsewhere without prior written consent of Adrian Hoskins / learnaboutbutterflies.com

Site hosted by Just Host