Sympetrum vicinum
fieldhawk

Sympetrum vicinum is widely distributed throughout much of North America. The species occurs throughout the most of the U.S. except the desert Southwest, the northern Rocky Mountains, peninsular Florida and the Gulf coasts of Louisiana and Texas. It's found in southeastern and extreme southwestern Canada. (Needham, Westfall, and May, 2000)

Sympetrum vicinum inhabits marshes, lakes, ponds and bogs in areas that are usually somewhat wooded. The ponds that this species inhabits must be permanent and have slow flowing water. (Needham, Westfall, and May, 2000)

Sympetrum vicinum has a dull yellow face, which in males becomes reddish toward maturity. The pterothorax is red on the front while the sides are an olive color. This species has reduced venation with hyaline (clear, colorless) wings with a yellow base. The abdomen is slender and red, and is lighter than in other species of Sympetrum. (Emmitt, 2000)

Eggs hatch in the early spring of the following year after overwintering. They emerge when the water temperature reaches about 10 degrees Celsius. At the beginning of the first free-living larval stadium (period between one molt and the next) ecdysis (shedding of the outer skin) occurs. This larval stage is restricted to the spring and summer seasons. After molting, the larva increases in size and changes in coloring can occur. This process takes place over about an hour.

After going through a series of molts S. vicinum begins showing signs of becoming an adult dragonfly. These signs include: setae on the dorsum of the head, contraction of the labium and microtrichia on the wings. It can take an individual anywhere from one to seven weeks to become ready to emerge as an adult. The first adults to emerge of this species are seen in late June. Once an individual has become an adult, it has two main goals: to eat and to mate. The pre-reproductive stage in S. vicinum can last anywhere from 30-87 days, depending on the latitude where they are found. Once they reach sexual maturity, individuals seek a mate, lay eggs and die soon afterward. (Corbet, 1999)

The life cycle of this dragonfly is approximately one year.

Sympetrum vicinum is a nonterritorial species. After mating, the male will keep hold of the female and they fly as a pair during oviposition. Dominance hierarchies have also been observed in S. vicinum. Disputes between competing males lead to an orderly ranking of individuals. Behavior can be affected by temperature. If an individual begins the morning in the shade it sometimes takes six extra hours for the insect's first flight of the day. (McMillian, 2000)

Odonates have highly developed sight. The large compound eyes are used to capture prey. (Merritt and Cummins, 1984)

The larvae of this species are sprawlers. They lie on pond bottoms and attack prey as it comes into their immediate area. The family of dragonflies that includes S. vicinum, Libellulidae, are all perching adults. This means that they sit and wait for their prey (small flying insects) to fly by. Once they see it, they take off and pursue it, with an amazing success rate of 97%. The study recording these data was done through keen observations from binoculars and video recorders. Trays were set out within patches of Eleocharis to maximize the test results by limiting the potential landing site area within two artificial ponds.

Foods eaten by larval S. vicinum include medium-sized water fleas and relatives of Cladocera; Ostracoda; Oligochaeta; burrowing and climbing flies of the family Chironomidae and Ceratopogonidae. Sympetrum vicinum will also eat larva of smaller dragonfly species. (Corbet, 1999; Olberg, Worthington, and Venator, 2000)

When spotted by predators the larvae form simply lies immobile. Large individuals, when attacked by the snake Regina alleni will actually bite the snake's mouth, which makes the snake bleed. Usually the snake will let go of the dragonfly larva. For some reason these snakes swallow dragonfly larvae head first. It has also been hypothesized, but not documented, that individuals may produce sounds to ward off predators. (Corbet, 1999; Olberg, Worthington, and Venator, 2000)

Dragonflies help keep insect populations at a stable level. Sympetrum vicinum has a commensal relationship with the species mentioned below and are also parasitized by certain species of mites. Parasitic chironomid fly larvae can be found on the back of the head, prothorax, wing sheaths and legs of S. vicinum. Spiroxys contortus uses S. vicinum as an intermediate host (turtles are the definitive host). (White, Weaver, and Fox, 1980)

Larva can sometimes deplete fish fry populations that fishermen want to culture. (Corbet, 1999)

Dragonflies can be used to protect humans from mosquitoes and blackflies. One experiment has show that larval species of Bradinopyga geminata were able to destroy an entire population of mosquitoes within a 194-liter drum in a matter of hours. Application of this method would allow pest control of mosquitoes without the use of chemicals. Several studies have show that Sympetrum species are apparently immune to pollutants. This could possibly help humans, in the long run, if we can develop ways to deal with pollutants if understood in detail. (Corbet, 1999)

This species is secure and currently not of any conservation concern.