Gomphus
graslinellus
(Pronghorn Clubtail)
Description:
Naiad-
This is a large naiad with a
maximum length of 1 1/8 inches (29 mm). The abdomen is widest at segment five.
There is a curved hook on the top of each abdominal segment two through nine,
and there is a single, rear-facing spine on each side of abdominal segments
seven through nine.
Adult-
This is a medium-sized dragonfly with
a length of 1 7/8 to 2 1/8 inches (47 to 53 mm). The face and thorax are olive
green, with the thorax marked with dark brown stripes. The abdomen is dark brown
to black and is marked along the top with a line of elongated, triangular-shaped
marks varying in color from greenish to yellow. The underside of the tip of
the abdomen is marked with yellow and is swollen as in other Clubtails.
Range:
This species is found from
southern British Columbia east to southwestern Ontario, extending south to Washington,
Oklahoma, and Missouri. In Idaho, it is found in the northern half of the state.
Habitat:
This dragonfly can be
found near lakes, ponds and slow streams.
Adult Flight Season:
Early June to
August
Diet:
Naiad-
Naiads feed on a wide variety of aquatic insects, such as mosquito larvae, other
aquatic fly larvae, mayfly larvae, and freshwater shrimp. They will also eat
small fish and tadpoles.
Adult-
The dragonfly will eat almost any soft-bodied flying insect including mosquitoes,
flies, butterflies, moths, mayflies, and flying ants or termites.
Ecology:
Clubtail naiads can
be very selective in their habitat choice and will often occur only in certain
stretches of a particular stream, lake, or pond. They burrow into the sand or
mud, leaving the upturned tip of their abdomen exposed. This allows them to
breathe while buried by pumping water in and out of the tip of the abdomen.
These naiads emerge as adults at the water's edge just before sunrise. Although
records are sparse, adults are believed to fly from early June to August. They
can not tolerate cooler temperatures and are rarely seen flying on cool or cloudy
days. Hunting occurs from perches on rocks or twigs.
Reproduction:
After males and females
mate, the female flies singly, without the male attached, to lay her eggs by
dipping the tip of her abdomen in rivers, lakes, or slow streams while hovering
above it.
Conservation:
Populations
are widespread, abundant, and secure.
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Global Rank: | G5 |
State Rank: | S? |
References:
Corbet, P. S. 1999.
Dragonflies: Behavior and Ecology of Odonata. Cornell University Press, Ithaca,
New York, USA, 829pp.
Logan, E. R. 1967. The Odonata of Idaho. Unpublished M. S. thesis. University of Idaho, Moscow, Idaho, USA, 105 pp.
Needham, J. G. and M. J. Westfall. 1955. Dragonflies of North America. University of California Press, Berkely, California, USA, 615 pp.
Paulson, D. R. 1999. Dragonflies of Washington. Seattle Audubon Society, Seattle, Washington, USA, 32 pp.
Walker, E. M. and P. S. Corbet. 1975. The Odonata of Canada and Alaska, Vol. III. University of Toronto Press, Toronto, Ontario, Canada, 307 pp.