Explanation of Names
The specific name cynosura is a Greek name for the Pole Star, more frequently called Polaris. "Cynosura" means "tail of the dog". More broadly, "cynosure" means "omething that strongly attracts attention or guides." Perhaps something on this dragonfly resembles a dog's tail. (Based on Internet searches.)
Identification of this species, is tricky. Some individuals have large basal spot on hindwings, like Mantled Baskettail, E. semiaquea, but spot does not extend to hindwing. Clear-winged form of Common Baskettail may be indistinguishable in the field from E. costalis and E. spinigera, etc.
Lakes, ponds, marshes, and slow-moving rivers.
One of the first dragonflies of spring. May fly as early as January in southeastern states. Flight extends to August, but most are about in spring, flight usually lasting about five weeks. May to August in Canada. Additional fall flight in Florida.
Predatory on other insects. May feed in swarms on such prey as winged termites.
Males patrol a patch of shoreline, about 3-10 meters long. Peak patrolling is in late afternoon.
Other Baskettails, Marl Pennant.
Dunkle, p. 142, plate 23, has extensive discussion of identification difficulties. (1)
Dunkle, pp. 63-64, fig. 53, also discusses id. issues. (2)
--good selection of photos