Common blue
Polyommatus icarus
Butterfly
The common blue (Polyommatus icarus) is a small lycaenid butterfly widespread across Europe, North Africa, and temperate Asia to northern China. Males are bright iridescent blue above with a dark border and white fringe; females are brown with variable blue dusting and orange marginal spots. Larvae feed on legumes, with bird's-foot trefoil (Lotus corniculatus), white clover (Trifolium repens), and black medick (Medicago lupulina) among the documented host plants; adults nectar low among grassland flowers. Gardens with legume lawns or meadow patches containing white clover or bird's-foot trefoil provide both larval and adult resources for this butterfly.
Conservation
IUCN Least Concern (2025 European assessment); UK populations have declined approximately 15% in distribution since the 1970s, associated with loss of herb-rich grassland and bird's-foot trefoil.
Plants in the catalog
Larval host plants · 1
White clover (Trifolium repens) is explicitly named as a larval foodplant; the butterfly's larvae feed on several legumes.
Range
Breeds throughout the Palearctic region from western Europe and North Africa east to northern China; in Britain it is the most widespread blue butterfly, found from southern England to Orkney and across Ireland. An introduced population first discovered near Montreal, Quebec, around 2005 is now well established and has spread into Ontario, suggesting the species may become more widespread in eastern Canada.
Sources & citations
Cite this page
Use this citation for the Plotwright wildlife record. Use the source cards below to explore the references that informed its taxonomy, range, conservation, host plants, foraging, and habitat.
Plotwright. (n.d.). Common blue (Polyommatus icarus). Retrieved 2026, August 20, from https://plotwright.com/wildlife/common-blue-butterfly
Sources used for this record
This record is compiled from the sources below.
Common blue - Wikipedia
Identification (blue male, brown female), the Palaearctic range with the eastern-Canadian introduction, the legume larval hosts including white clover, and adult grassland nectaring.
Common blue - UK Butterflies
UK Butterflies species account for the common blue, covering its British distribution, brood structure, legume larval foodplants such as birdsfoot trefoil, and adult grassland nectaring.
Polyommatus icarus - GBIF
GBIF backbone taxonomy record for Polyommatus icarus, confirming the accepted species and its Palearctic occurrence range.
Polyommatus icarus - iNaturalist
iNaturalist taxon page for Polyommatus icarus, corroborating the accepted name and observation-based distribution.