Genus POLYOMMATUS, Latreille , 1804 
THE COMMON BLUE 
Polyomrnatus icarus (Rott., 1775). 
(Plate XXI, facing page 240) 
As its name implies, the Common Blue is the most abundant 
of the British Lycaenidae and one of the most beautiful, 
especially in regard to the aberration in the colouring of many 
forms of the females. 
Haunts and Distribution. — Except for the Shetland 
Islands, this little butterfly ranges throughout the United 
Kingdom. It is to be met with almost everywhere from sea 
level to high up the mountain side. Its favourite haunts are 
rough, flowery hillsides, Clover fields in bloom, downs, and 
all waste uncultivated land abounding with Bird's Foot Trefoil 
(Lotus corniculatus), the food plant of the larva. Abroad it 
occurs throughout Europe, North Africa, the northern and 
western regions of Asia, Amurland and China. 
Time of Appearance. — This common species is double- 
brooded. The first brood appears on the wing from May to 
July ; eggs laid at the end of May and in June produce the 
second emergence of butterflies in August and September ; 
sometimes freshly-emerged examples appear on the wing in 
October ; these result from eggs laid by late individuals in 
July. Therefore, this butterfly is on the wing from the 
middle of May until October. In northern Scotland and in 
Ireland there is only one brood in the year, this is in June and 
July. 
Like most of its allies, the Common Blue rests during dull 
weather and at night on the flower-heads and stems of grasses 
and other low-growing plants. Towards evening it retires 
to rest and after alighting, turns round and rests head down¬ 
wards, in which position it remains until the approach of 
darkness, when it reverses its posture and rests head upwards 
for the night. They frequently assemble in numbers, often 
six or seven on the same stem, and I have seen as many as 
two dozen or more on the same plant, also they commonly 
associate with other species. 
The flight of this charming little butterfly is rather rapid. 
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