The 'Common Whitetail' or 'Long-tailed Skimmer', ''Libellula lydia'' is a common
dragonfly across much of
North America, with a striking and unusual appearance. The male's chunky white body (about 5 cm long), combined with the brownish-black bands on its otherwise translucent wings, give it a checkered look. Females have a brown body and a different pattern of wing spots, closely resembling that of female ''
Libellula pulchella'', but can be distinguished by their smaller size, shorter bodies, and white zigzag abdominal stripes; L. puchella's abdominal stripes are straight and yellow.
[1]

An immature male Common Whitetail.

A mature male, with white abdomen.
The Common Whitetail can be seen hawking for
mosquitoes and other small flying insects over ponds, marshes, and slow-moving rivers in most regions except the higher mountain regions. Periods of activity vary between regions; for example in
California, the adults are active from April to September.
Like all
perchers, Common Whitetails often rest on objects near the water, and sometimes on the ground. Males are territorial, holding a 10 to 30 metre stretch of the water's edge, and patrolling it to drive off other males. The white
pruinescence on the
abdomen, found only in mature males, is displayed to other males as a territorial threat.
[2]
The nymphs are dark green or brown, but are usually found covered in algae. They feed on aquatic invertebrates such as
mayfly larvae and small
crayfish, and also on small aquatic vertebrates such as
tadpoles and
minnows. Because of their abundance, whitetail naiads are in turn an important food source for various fish, frogs, and birds, and also for other aquatic insects.
Some authorities classify the whitetails, including the Common Whitetail, in
genus ''Plathemis'' rather than ''Libellula''. This matter has been debated at least since the end of the
nineteenth century. Recent
molecular systematics evidence suggests that separation of the whitetails from the rest of ''Libellula'' may be appropriate.
References
1. Dragonflies through Binoculars, , Sidney W., Dunkle, Oxford University Press, 2000, ISBN 0-19-511268-7
2. A Study of Territoriality and Breeding Behavior in Pachydiplax longipennis Burmeister (Odonata:Libellulidae), , Clifford, Johnson, The Southwestern Naturalist,