Libellula
(Ladona) julia
(Chalk-Fronted Corporal)
Description:
Naiad-
This is a medium-sized naiad with a length of 15/16 to 1 inch (24 to 25 mm).
It is dark brown in color. The abdomen is rounded, giving it a short, stocky
appearance known as the sprawler form. There are hooks on the tops of abdominal
segments four through eight (the hook on segment six is noticeably longer),
and a single, slender, rear-facing spine on each side of abdominal segments
eight and nine.
Adult- This
is a medium-sized dragonfly with a length
of 1 5/8 to 1 13/16 inches (41 to 45 mm). The wings
are clear except for a patch of brown at their bases (where they attach to the
body). Immature males and females
are uniformly dark brown on the thorax and abdomen.
Both mature males and females have a powdery-appearing coating (a condition
called pruinosity) on the thorax and the first part of the abdomen; in males
it is bluish white while in females it is grayish. The rest of the abdomen is
blackish brown, possibly fading to orangish brown along each side.
Range:
This dragonfly has a fairly
narrow but lengthy range centered on the U.S.-Canadian border, extending from
British Columbia and Washington east to Nova Scotia and Maine. It occurs in
the northern half of Idaho at low elevations.
Habitat:
This dragonfly can be
found near nutrient-poor lakes, ponds, and marshes. Unlike most Libellula, this
species seems to prefer acidic waters like peat bogs.
Adult Flight Season:
Mid-June to September
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:
The naiads live on the
bottom in decaying vegetation. They do not actively pursue prey but wait for
it to pass by, a strategy which affords them protection from other predators.
Naiads emerge as adults at night. Although records are sparse, the adults are
believed to fly from mid-June to September. Hunting occurs from perches on vegetation.
Reproduction:
After males and females
mate, the female flies singly, without the male attached, to lay her eggs. She
does this by dipping the tip of her abdomen in the shallows of lakes, bogs,
and ponds while hovering just above its surface.
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.