Lycaenid larvae, rather slug-like. Geographic range The common blue butterfly is found in Europe, North Africa, the Canary Islands, and east across the Palearctic to Northern China. Recently it was discovered in Quebec, Canada. It is widespread in the British Isles. Its distribution trend shows a 15% decline since the 1970s. U.K. and Ireland The common blue is Britain and Ireland's (and probably Europe's) most common and most widespread blue. It is found as far north as Orkney and on most of the Outer Hebrides. A range of grassland habitats are used: meadows, coastal dunes, woodland clearings, and also many man-made habitats, anywhere their food plants are found. North America This is a recently introduced species in eastern Canada. It was discovered in Mirabel, Quebec, Canada, by Ara Sarafian, an amateur entomologist who observed the butterfly from 2005 to 2008. He contacted the Canadian National Collection of Insects in Ottawa where the butterfly was identified as Polyommatus icarus, a newly introduced butterfly to Canada and to North America. The butterfly seems to be well established and is extending its range from year to year. A study from Montreal, Quebec, Canada showed that the common blue is most abundant in areas with greater urban land cover and where their preferred larval host plant, bird's foot trefoil (Lotus corniculatus), can be found. Habitat These butterflies inhabit flowery or grassy places, warm and cool, open or wooded areas and at all altitudes up to high alpine meadows at an elevation of above sea level. It mostly resides on chalk or limestone grassland, but also in smaller numbers in woodland clearings, meadows, heathlands, sand dunes, along railway embankments, and under cliffs. Source of decline Previously, P. icarus was a very common species that occupied Europe and Asia, and was one of the most widely distributed butterflies in Britain. It is known to be tolerant of many habitats, including a wide range of grasslands. There has been an estimated 74% loss of the butterfly population since 1901. This could be due to the fact that 46% of the total land area covered by the butterfly's preferred host plant, Lotus corniculatus, has also been lost since 1901. This host plant is a favored plant for two reasons: it provides adult nutrition, as well as food for the larva after it hatches. Food resources Larval food plants The larvae feed on plants from the bean family, Leguminosae.