June 2011. Butterfly Conservation members from around Scotland set their moth traps at orchid sites this month in an attempt to catch and identify the pollinators of Lesser Butterfly-orchid.
The flowers of Lesser Butterfly-orchid are adapted for pollination by night-flying moths being bright white, almost glowing in the dark, becoming more strongly scented around dusk and providing large quantities of sugary nectar in their long spurs, only accessible to insects with a sufficiently long proboscis. However, the particular moth species which pollinate the flowers of Lesser Butterfly-orchid in Scotland are currently unknown – a gap in our knowledge that must be addressed if we are to successfully conserve the species.
Upon visiting the flower and inserting its proboscis to probe for nectar in the spur, the moth becomes an unwitting servant of the orchid as the pollen, which is aggregated into units called pollinia, becomes attached to their proboscis by a sticky pad at the base. When the moth moves on from the flower it carries with it the pollinia which, after a short time, turn to face forwards enabling them to come into contact with the stigma of the next flower visited by the moth, and hence pollination takes place. This intricate mechanism leaves behind a clue as to the identity of the moth pollinator as the pollinia attached to the base of the moth’s proboscis are visible upon close inspection.
With real enthusiasm from Butterfly Conservation members, and traps running at five different Lesser Butterfly-orchid sites in Scotland, we looked set to solve this pollination mystery. However, the good old Scottish weather refused to co-operate with our grand plans with cool and wet conditions leading to poor moth activity throughout much of the orchid’s limited flowering period and, unfortunately, success was rather limited and the mystery shall remain with us for another year!
All was not lost though as some moths were trapped carrying the pollinia of other orchid species - just not the one we were looking for! See below pictures of an Elephant Hawkmoth and Beautiful Golden Y, trapped by Mike Taylor and Pete Moore at Glencairn Meadow near Boat of Garten, carrying the pollinia of Heath Fragrant Orchid (Gymnadenia borealis) on their proboscises.