Libellula forensis
(Eight-Spotted Skimmer)


Order: Odonata
Suborder: Anisoptera
Order Description:
Dragonflies
Family: Libellulidae
Family Description: Skimmer

Description:
   Naiad- This is a medium-sized naiad with a length of 3/4 to 7/8 inch (18 to 21 mm). 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 six, and a small nub (a remnant of a hook) on segment seven. Each side of abdominal segments eight and nine has a short, rear-facing spine.
   Adult- This is a large Skimmer, with a length of 1 13/16 to 2 1/16 inches (45 to 51 mm). It has a broad abdomen. The base color is brownish black. Mature males may be covered with a powdery blue coating on the thorax and abdomen (a condition called "pruinose"), although specimens from the West Coast may lack it. Females and immature males are marked with yellow or orange on the top and sides of the thorax and along each side of the upper surface of the abdomen. The "eight spots" sited in the common name refer to the total number of spots occurring on the wings. Each wing has two large, dark spots, one near the base and one about halfway out that spans the width of the wing. The stigma is also dark.

Range:
This species is found from southern British Columbia east to Montana, extending south to California east to Nebraska. It occurs throughout Idaho at low elevations.

Habitat:
This dragonfly can be found near weedy lakes and ponds at low elevations.

Adult Flight Season:
Early June to mid-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:
The naiads live in submerged vegetation and mud at the bottom of lakes and ponds. 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, often after crawling a considerable distance from the water. Adults generally fly from early June to mid-August. They hunt from perches on twigs and rocks. This species is very common and conspicuous at large weedy lakes. It closely resembles Libellula. pulchella, but lacks the dark spots on the wing tips.

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 and ponds while hovering just above its surface.

Conservation:
Populations are widespread, abundant, and secure.
Status: Unprotected nongame species
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.


Written by Mark Lung and Stefan Sommer, 2001
Photos by Dennis Paulson, 2001
Design by Ean Harker, 2001.

HTML by Marty Peck, 2001.