United States and Canada
In the field, males appear mostly reddish-brown with a red wash extending onto the wings. When perched, the habitat, habits and darker red and patterned thorax and abdomen separate males from superficially similar red skimmers. Females appear patterned gray overall.
This is a moderate-sized dragonfly found throughout the southwestern parts of the region. Young males and females have a pale face, but it becomes bright red along with the vertex in older males. The thorax and abdomen are brownish-gray heavily marked with black. The front of the thorax has a dark rectangle anteriorly. There are two large dark spots, one in front and one below the humeral suture, that are visible from the side. The mid- and third lateral sutures, along with rear margin of the pterothorax are each marked with a heavy, but irregular, black stripe. The wings each have a broad area of flavescence basally that is more pronounced in males and a darker stripe on either side of the midbasal space. The legs are pale externally and dark on the inside. The abdomen is marked with black on the carinae and irregularly so on the rest of each segment. The front of the thorax and the en tire abdomen in mature males is red.
Size: Total length: 44-53 mm; abdomen: 29-36 mm; hindwing: 41-46 mm. Similar in size to a Flame Skimmer, which it resembles, but somewhat more lightly-built and slender.
Similar Species This species may be confused with several other red species with which it co-occurs. Red Rock Skimmer is darker and more heavily-patterned then these others.
Mayan Setwing (Dythemis maya), Neon (Libellula croceipennis) and Flame (L. saturata) Skimmers all have an unmarked thorax and abdomen.
Red Rock Skimmers nearly always perch horizontally on rocks near streams.
Habitat: Tightly associated with small, sunlit, rocky, forest streams. Perches on large rock banks near the water.
Natural History: Perches flat on rocks near water.
It is unique among skimmers in combining the broad hindwing of glider dragonflies (Pantala and Tramea) with the behavior of perchers and fliers. Adults make a habit of gliding during both feeding and patrolling flights. When perched, they nearly always do so horizontally on rocks or vertically on bridge pillars.
Males patrol small 15 m sections of streams where the water trickles through the rocks early in the morning, rarely being seen after midday. Mating takes place in flight and subsequent egg laying by females occurs alone or guarded by the male. Females rapidly drop to the water from a height of 12 cm, dipping the abdomen in regular 1 sec. intervals.
One study found that males, in the absence of intraspecific competition, defended territories more than twice as large as those defended during a high-density year, as defined by a high rate of male-male interactions, and regular raiding of neighboring territories to steal females. Further studies showed males engage in meandering searching flights to locate potential egg deposition sites in their territories. This is followed by a n inspection flight of a suitable place that will be displayed to the female after capturing her.
Distribution: Southwestern U.S. and Mexico south to Costa Rica.
Source: Abbott, J.C. 2006-2010. OdonataCentral: An online resource for the distribution and identification of Odonata. Available at OdonataCentral.
Edited by Drew Weber (9/24/2015). Edited by David A. Bell (9/29/2015).
