Tramea
lacerata
(Black Saddlebags)
Description:
Naiad-
This is a medium to large naiad, with a length of 15/16 to 1 inch (24 to 25
mm). It is pale green and marked with light brown. The head is large and the
eyes are big. The last abdominal segments each have a single, large, flattened
and slightly curved spine on either side.
Adult- This
is a large dragonfly with a length
of 2 to 2 3/8 inches (50 to 55 mm). It is largely black
with hints of metallic royal blue. It has a distinctive wavy black band of black
spanning the width of each hindwing near where it attaches to the body, which
gives it a humpbacked appearance in flight. The hindwings are triangular and
noticeably broad.
Range:
This species is found from
southern Washington east across the U.S. to Massachusetts, extending south to
California, Texas, and Florida. It also occurs in Mexico and the Hawaiian Islands.
In Idaho, it occurs throughout the Snake River Plain from Twin Falls west to
the Oregon border, and north along the Snake River to Lewiston.
Habitat:
This dragonfly can be
found near ponds and lakes with abundant aquatic vegetation.
Adult Flight Season:
Early July to
early October
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
very small fish and tadpoles.
Adult-
The dragonfly will eat almost any soft-bodied flying insect including mosquitoes,
flies, small moths, mayflies, and flying ants or termites.
Ecology:
The naiads live in debris
and submerged vegetation on the bottom of ponds and lakes and actively pursue
prey. Adults generally fly from early July to early October. This species can
be observed migrating south in August and September, often with the Common Green
Darner (Anax junius) and the Variegated Meadowhawk (Sympetrum corruptum). The
adults that appear in Idaho in the early part of the flight season generally
emerged in the southern portion of their range and have migrated north. In Idaho
they produce a successive generation that emerges later in the summer to early
fall and migrates south, where it again reproduces.. The adults hunt throughout
the day primarily while flying. When they do perch, they generally hang vertically
on the underside of branches or twigs, rather than sitting on top like most
members of this family. This dragonfly appears to be deeply suspicious of humans
with nets and so is often underrepresented in collections from areas where it
is quite common.
Reproduction:
The female flies with
the male still attached after mating (a position called "in tandem") and lays
her eggs in lakes and ponds by dipping the tip her abdomen on the surface of
the water. However, the male releases the female just before her abdomen touches
the water, and then grabs her again with his abdominal appendages as she rises.
In this way, he avoids being eaten by fish while still preventing other males
from mating with his chosen female.
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.