- Habitat Regions
are known for their large compound eyes each separated by more than their own body width, muscular mandibles, very slender, elongate ten-segmented abdomens, short legs used mostly for perching, and tiny filiform antennae. Sight is their most specialized sense. Unlike the dragonfly, their two pairs of large wings stand straight up over their 7-8 cm long bodies. The female adult has a black humeral stripe, lacking the pale spot located at the base of the median ocellus that the males exhibit. Females also have specialized ovipositors whose primary function is to cut holes in the stems of submerged plants in order to receive eggs. Adults are called "darning needles" or "mosquito hawks" due to their size, which decreases with advancing season.
Each adult female usually has 11 to 14 nymphs, whose life cycles take up to one year. The eggs and larvae have caudal and rectal gills. (Brackenbury, 1994; Brusca and Brusca, 1990; Corbet, 1999; Merritt and Cummins, 1984; Pennak, 1953)nymphs are identified by their three leaflike tracheal gills at the tip of their abdomen and their usually robust green or grey color. Nymphs are usually 10-15 mm long, not including their gills. The bodies of the nymphs bear small spines and are often covered with algae and debris. They have five labial setae or food getting devices armed with stout teeth.
- Sexual Dimorphism
- sexes colored or patterned differently
- Range length
- 7 to 8 cm
- 2.76 to 3.15 in
Flight time occurs from May to November. Mating is a very specialized and time-dependent process and occurs at rest or during flight. Females mate only once per clutch laid. Each adult female usually has 11 to 14 nymphs. The male is nonterritorial, the oviposition site rendezvous is widely dispersed and there can be multiple matings per day. In studies, females mated a second time with the same male in only 7.6% of cases and a third time only 0.9% of the time. Three percent of males and 5% of females had the same distributions for mating frequency. The sex ratio in studies was 50%. Mating and reproduction were directly related to the number of sunny days in which the male was sexually active.
When mating, the male grips the female around her neck with two of his pairs of claspers at the end of his abdomen. The female then arches her abdomen forward and under to come into contact with the sperm. Sperm is stored in the male's accessory genitalia on the underside of his thorax. (Biggs, 2005; Brackenbury, 1994; Brusca and Brusca, 1990; Corbet, 1999; Pennak, 1953)oviposits in tandem, which is unusual in that the male possesses a "scoop" on his penis. This scoop's sole purpose is probably to displace the sperm. Post-copulatory guarding prevents sperm from being displaced by a rival mate. When the time has come to deposit the eggs, the female inserts them in plant tissue above or below water, sometimes in masses of green algae. The pre-reproductive period is 5-7 days.
Communication and Perception
- Communication Channels
mosquitoes, annelids, small crustaceans, and mollusks. They usually catch their food on their wing after stalking the prey by remaining motionless until the food comes within reach and is seized by rapid extension and contraction of the labium. The labium then holds the food in their mouth where it is crushed easily by the strong mandibles. (Brackenbury, 1994; Brusca and Brusca, 1990; Merritt and Cummins, 1984; Pennak, 1953)are carnivorous insects that prey on
- Animal Foods
- aquatic or marine worms
- aquatic crustaceans
Economic Importance for Humans: Positive
The San Francisco fork-tailed damselfly has no positive economic benefits to humans.
Economic Importance for Humans: Negative
This species also has no negative economic benefits to humans.
This damselfly is not listed as endangered or threatened, but is considered rare in its range. (Biggs, 2005)
Respiration takes place through the thoracic spiracles with the caudal lamellae or gills acting as supplementary respiratory structures, unlike the rectum which is the primary respiratory structure in most Odonata. (Corbet, 1999; Merritt and Cummins, 1984)
Jana Marshall (author), Southwestern University, Stephanie Fabritius (editor), Southwestern University.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
- bilateral symmetry
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- brackish water
areas with salty water, usually in coastal marshes and estuaries.
an animal that mainly eats meat
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
- active during the day, 2. lasting for one day.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
union of egg and spermatozoan
mainly lives in water that is not salty.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
(as keyword in perception channel section) This animal has a special ability to detect heat from other organisms in its environment.
An animal that eats mainly insects or spiders.
- internal fertilization
fertilization takes place within the female's body
eats mollusks, members of Phylum Mollusca
having the capacity to move from one place to another.
- native range
the area in which the animal is naturally found, the region in which it is endemic.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
- seasonal breeding
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
uses sight to communicate
Biggs, K. 2005. "Damselflies (Zygoptera) of the Southwest" (On-line). Accessed March 02, 2005 at http://southwestdragonflies.net/damsels/swzygoptera.html.
Brackenbury, J. 1994. Insects:Life Cycles and the Seasons. New York: Sterling Publishing Co., Inc..
Brusca, R., G. Brusca. 1990. Invertebrates. Sunderland, Massachusetts: Sinaur Associates, Inc..
Corbet, P. 1999. Dragonflies:Behavior and Ecology of Odonata. Ithaca, New York: Cornell University Press.
Farb, P., The Editors of LIFE. 1962. The Insects. New York: Time, Inc..
Merritt, R., K. Cummins. 1984. An Introduction to the Aquatic Insects of North America. Dubuque, Iowa: Kendall/Hunt Publishing Company.
Pennak, R. 1953. Fresh-water Invertebrates of the United States. New York: The Ronald Press Company.