Pronghorn Clubtail

phanogomphus graslinellus

The Pronghorn Clubtail (Phanogomphus graslinellus) is an elegant, medium-sized dragonfly belonging to the clubtail family, Gomphidae. Highly adapted to riverine and lakeside ecosystems across North America, these insects are remarkable aerial predators that spend their days hunting on the wing or basking on sunny rocks and paths near the water's edge. Like other clubtails, they get their name from the distinctively widened segments near the tip of their abdomen, which looks like a small club. They serve as valuable biological indicators of water quality, as their nymphs require clean, oxygenated aquatic environments to develop.

Habitat: Found near slow-moving muddy or sandy-bottomed rivers, streams, lakes, and ponds.

Appearance

This dragonfly typically measures between 4 and 6 centimeters in length, with a wingspan of 6 to 8 centimeters. It possesses a dark brown or black abdomen accented with bright yellow-green spots along the top, ending in a noticeable 'club' shape. The thorax is vivid green or yellow, patterned with bold dark brown stripes, and its widely separated compound eyes are a brilliant grey-green or blue-green color. Males can be distinguished by the small, horn-like prongs on their terminal appendages, giving the species its common name.

KingdomAnimaliaPhylumArthropodaClassInsectaOrderOdonataFamilyGomphidaeGenusPhanogomphus

Pronghorn Clubtail

Interesting facts

The 'pronghorn' in their common name refers to the tiny prong-like projections on the male's claspers, which are used to hold the female during mating.

They spend up to two years of their life cycle as aquatic nymphs underwater, but live for only a few weeks as winged adults.

Unlike most other dragonflies that perch on twigs or leaves, clubtails prefer resting flat on the ground, bare soil, or flat rocks.

Special abilities

Features large, widely separated compound eyes that provide an almost 360-degree field of view to spot prey and evade predators.

Capable of rapid acceleration and agile banking maneuvers to intercept flying insects mid-air with high precision.

The aquatic nymphs possess flat bodies and specialized legs designed for burrowing into sandy or muddy riverbeds to ambush prey.

Measurements & details

Length: 4-6 cm
Wingspan: 6-8 cm
Weight: 0.001-0.002 kg
Lifespan: 1-2 years
Top Speed: 30 km/h
Clutch Size: 100-500
Incubation: 10-30 days

Diet & Feeding

Adults are active aerial predators that hunt flying insects, whereas the aquatic nymphs ambush small aquatic organisms from the riverbed.

Age differences: Nymphs live underwater and feed on aquatic invertebrates like mosquito larvae and small worms, whereas adults are purely aerial predators feeding on flying insects.