New York Natural Heritage Program
Delaware River Clubtail
Gomphus septima delawarensis (Donnelly and Carle, 2000)
Insects

General Description [-]
This is a rather large dull green and brown dragonfly with the lateral thoracic stripes nearly absent, no black facial stripes, and a small abdominal club which has small pale lateral spots. Mature larvae are larger than most other Gomphids. Gomphus septima delawarensis is different enough from its close relative, G. s. septima that it could have been described as a separate species, rather than as a subspecies (see, Donnelly and Carle, 2000).

Identifying Characteristics [-]
Adults look and behave similarly to the Midland Clubtail (Gomphus fraternus); older larvae are much larger than most other clubtails.

Characters Most Useful for Identification [-]
Larger size.

Best Life Stage for Proper Identification [-]
Exuviae (shed skins) along river banks. Adults rarely observed.

Behavior [-]
Although adults are elusive and have rarely been seen, some observations from the mid 1990s indicate that males spend time perched on rocks and logs at breeding habitats. Both sexes feed in nearby clearings where they rest on the ground and flat on leaves. Some fly high into the treetops to copulate, while other pairs remain low over the grass. This species often leaves the water during the heat of the day. Mating has been observed as late as 2:00 pm and oviposition even later. Females have been observed extruding eggs while perched on a rock, and then flying over the water in wide loops, tapping three times in 4-minute intervals and then flying into the treetops. Adults frequent regions of turbulent rapids with large emergent boulders, on which they often perch. Emergence occurs farther up on the river banks (1-2 meters) than most other Gomphids.

Diet [-]
Larvae feed on smaller aquatic invertebrates and adults feed on insects which they capture in flight.
Delaware River Clubtail Images
click to enlarge
The Best Time to See
Exuviae (shed skins) and adults have been collected along the upper Delaware from May 24-June 25, with the great majority of records coming during the first half of June.
 
J F M A M J J A S O N D
Reproducing Larvae present and active
The time of year you would expect to find Delaware River Clubtail reproducing (blue shading) and larvae present and active (orange shading) in New York.
Similar Species
  • Midland Clubtail (Gomphus fraternus)
    The Midland Clubtail is usually blacker and has a more evident dorsal spot on the abdomen.