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A magnificent insect of the moorlands of Coigach is the gold-ringed dragonfly (Cordulegaster boltonii). This beautiful creature has a long black body, which is ringed with a series of thin, bright gold bands, and
broad transparent wings that glitter in the sunshine as it hawks rapidly for insect prey. If it comes close you can hear a dry rustle from the rapid beat of its wings. On
dull days you may sometimes find it at rest on the heather and may then see the huge compound eyes, which take up most of the head and help it to see its
flying prey so clearly. When perched, dragonflies hold their wings out horizontally, whereas their smaller cousins, the damselflies, fold theirs over their bodies. When flying, both species
beat their fore and hind wings out of phase. In this they differ from other insects, which tend to link the action together in a synchronised fashion. All dragonflies have aquatic larvae,
which prey voraciously on other insects, tadpoles or even small fish, using an extensible 'mask' that is tucked under the head when not in use.
When an unwary insect comes sufficiently close the mask shoots out and the sickleshaped jaws pierce and hold the prey. Most dragonfly larvae live in pools or lochans but those of
the gold-ringed dragonfly are found in small sandy or gravely streams. They are rather squat and lie hidden under the debris on the stream bottom, with only their eyes and tail visible.
The tail is important because dragonfly larvae get their oxygen from the water and they suck this in and out of a chamber connected to the tail. If they need to, they can squirt water out
explosively, giving them a form of jet propulsion that jerks them forward rapidly. In mainland Europe the gold-ringed dragonfly has become rather rare and localised, largely
because so many of the streams it usually inhabits have become polluted or otherwise altered. Scotland is therefore an important refuge for the species, especially in the northwest
Highlands where so much unpolluted moorland remains. You can hope to see it from late May right up to the end of August. |
