New York Natural Heritage Program
Gray Petaltail
Tachopteryx thoreyi (Hagen in Selys, 1858)

Identifying Characteristics [-]
Gray petaltails are large black and gray dragonflies that are often seen perching on tree trunks. While they resemble some of the species of mosaic darners (genus Aeshna), they are easily distinguished from them by their well-separated eyes,and the long, parallel-sided stigma on the wing. The eyes are dark brown to gray. The thorax is mainly gray, while the abdomen is gray with black markings. Adult gray petaltails are approximately 7.1-8.0 cm in length. Females are similar to males, but have a well-developed blade-like ovipositor. The larvae can be recognized by their short, thick, and hairy 7-jointed antennae and by the quadrate form of the prementum and the strongly- angulated side margins of the abdominal segments (Needham et al. 2000).

Characters Most Useful for Identification [-]
The well-separated eyes and the long, parallel-sided stigmas on the wings are important characters for this species, although its large size and black and gray color make it difficult to confuse with any other northeastern dragonfly species.

Best Life Stage for Proper Identification [-]
Mature adults are the best life stage for the identification of all dragonflies. Although the identification of larval dragonflies requires the use of detailed taxonomic keys, can be very difficult, and can be very unreliable, especially in the case of larvae that are not yet mature, the larva of this species is easier to distinguish than the larva of many other species. Larval identification is best done by people with a great deal of expertise in this area.

Behavior [-]
The behavior of adult gray petaltails is quite interesting. They frequent sunny openings at, or near, the hillside seepages where males chase one another and wait for females to enter the habitat, mate and oviposit. Males also will fly up the length of large tree trunks searching for females and both sexes frequently perch on tree trunks. Adult petaltails are easy to approach, not wary of people and in fact will frequently land on people. At the same time, they are swift of flight and are difficult to follow when they do take flight (Dunkle 1981, Needham et al. 2000, Nikula et al. 2003).
Gray Petaltail Images
click to enlarge
The Best Time to See
The majority of the New York records and observations for this early-season species are from mid June through mid July, although there are also records from early June and into early August (New York Natural Heritage Program 2006, Donnelly 1999).
Present Reproducing
The time of year you would expect to find Gray Petaltail present (blue shading) and reproducing (orange shading) in New York.