David Tipling / Two male Greater prairie chickens (Tympanuchus cupido) fighting on lekking ground in the Sandhills, Nebraska. USA, April

Russell Cooper / Mating pair of Small Blue Butterflies (Cupido minimus) on plant stem, Surrey, England, UK

Gerrit Vyn / Aggressive encounter between two male Greater Prairie-Chickens (Tympanachus cupido) on a lek. During these aggressive encounters, males lower their pinnae feathers, deflate their air sacs, leap into t...

Gerrit Vyn / Aggressive encounter between two male Greater Prairie-Chickens (Tympanachus cupido) on a lek. During these aggressive encounters, males lower their pinnae feathers, deflate their air sacs, leap into t...

Tim Fitzharris / Greater Prairie Chicken (Tympanuchus cupido) male in courtship display, Eagle Lake, Texas

Paul Hobson / Small blue adult, Cupido minimus, pair mating on common spotted orchid, Bedfordshire

Paul Hobson / Small blue adult, Cupido minimus, pair mating, Bedfordshire

Andy Sands / Small blue butterfly (Cupido minimus) mating pair, Hertfordshire, England, UK, May

Andy Sands / Small blue butterfly (Cupido minimus) female laying eggs among flowers of Kidney Vetch (Anthyllis vulneraria), Hertfordshire, England, UK, May

Lorraine Bennery / Osiris blue butterfly (Cupido osiris) on flower, Grands Causses Regional Natural Park, France, May.

Lorraine Bennery / Mating pair of Small Blue Butterflies (Cupido minimus) and Chalkhill blue butterflies (Lysandra coridon) mating, Hautes-Alpes, France, May.

Rod Williams / Small blue butterfly (Cupido minimus) male hoping to mate with female on their foodplant, kidney vetch Hutchinson's Bank, New Addington, London, England, UK. June.