There are three populations of Dukes' skippers (Opler and Krizek, 1984), all are in the eastern North America: 1) along the Atlantic Coast from southeast Virginia to northern peninsular Florida, 2) the lower Mississippi Valley from central Missouri and southern Illinois south to the Gulf Coast, and 3) southern Ontario, southeastern Michigan, northeastern Indiana, and northern Ohio.
In Ohio, they are primarily found in the Black Swamp area, and in Michigan occur in the southeastern portion of the state. The subspecies E. dukesi calhouni inhabits the southern United States coastal plain and is endemic to Florida. E. dukesi dukesi and E. dukesi calhouni are allopatric and closely approach one another in northeastern Florida and southeastern Georgia, however, there is no known intergradation. Individual populations appear to be widely separated, a contributing factor in their rarity. (Iftner, et al., 1992; Nielsen, 1999; Opler and Krizek, 1984; Shuey, 1996)
The endemic nature of E. dukesi calhouni was recognized in the mid -1990's. Shuey (1995) speculates that their isolation from populations on the North American mainland may be attributed to Pleistocene glacial events. (Shuey, 1995)
This species prefers shaded wetlands dominated by the larval foodplant Carex lacustris, including coastal swamps and ditches. In Merriam's Life Zone classification, they are found in the Lower to Upper Austral Life Zones. In the southern portions of their range, E. dukesi dukesi inhabit shaded tupelo swamps and utilize Carex hyalinopepis as their larval foodplant. In Ohio, populations exist in low densities in scattered patches along railroad right-of-ways through swampy woodland and in small, natural clearings within woodlands. They are often associated with buttonbush (Ceanothus occidentalis). (Iftner, et al., 1992; Nielsen, 1999; Opler and Krizek, 1984; Pyle, 1995; Scott, 1986)
In Florida, E. dukesi calhouni has been found in at least five types of forested wetlands. They are limited to swamp habitats that contain large stands of their sedge hostplants. (Shuey, 1995)
- Habitat Regions
Dukes' skippers range in size from 32-38 mm (1¼-1½ in) and have short, rounded wings. Females are slightly larger than males. The upper surfaces of the wings in both sexes are deep brown. The females have a hindwing band that has two to three pale yellow spots. Males have a black stigma on the forewing. The underside of the hindwings are light brown with pale yellow rays. (Opler and Krizek, 1984; Pyle, 1995; Scott, 1986)
The caterpillars of this species have a black head and light green body. The pupae nest in sedge leaves; they tie themselves into the upper portion of plants with silk. (Nielsen, 1999)
- Sexual Dimorphism
- female larger
- sexes colored or patterned differently
- Range wingspan
- 32 to 38 mm
- 1.26 to 1.50 in
There is no published literature at this time concerning the development of Dukes' skippers, however, it can be assumed that they follow the general lepidopteran life cycle of egg, five instars, pupae and adult. Caterpillars are known to overwinter in the fourth stage, and emerge from diapause in the springtime to feed on their larval foodplants. They will then molt one last time before pupation. The duration of the pupal period is not reported, but probably falls between one to two weeks. (Opler and Krizek, 1984)
- Mating System
- polygynandrous (promiscuous)
In the southern part of their range, Dukes' skippers have three flights from mid-May through October. Farther north there are two flight periods; mid-June to mid-July and late July to early September. In the lower Mississippi valley the two flight periods run from mid-May through June and mid-August to early October. In Ohio, southern Ontario, southeast Michigan, and northern Indiana, Dukes' skippers have one brood that flies during late June through early August. After mating, females lay their eggs under the leaves of their host plants, sedges in the genus Carex. After hatching, the larvae undergo several molts and diapause in the fourth instar stage. (Glassberg, 1999; Iftner, et al., 1992; Nielsen, 1999; Opler and Krizek, 1984; Pyle, 1995)
The time of mating differs depending upon where the population is in the species' range. After mating, females lay their eggs under the leaves of their host plants. After hatching, the larvae undergo several molts and hibernate in the fourth larval stage. (Glassberg, 1999; Iftner, et al., 1992; Nielsen, 1999; Opler and Krizek, 1984; Pyle, 1995)
- Key Reproductive Features
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- Breeding interval
- Dukes' skippers are univoltine in the north to trivoltine in the south.
- Breeding season
- Each flight period lasts approximately one month.
No parental care is given for Dukes' skippers.
- Parental Investment
- no parental involvement
From hatching through the death of the adult stage, a Dukes' skipper probably lives about a year or less. Several months of that time may be spent dormant in the winter. The estimated lifespan of an adult Dukes' skipper in the wild is approximately three weeks.
- Typical lifespan
- 1 (high) years
- Typical lifespan
Dukes' skippers have a weak flight pattern and are most often seen flying within sedges or visiting nectar plants. E. dukesi calhouni frequent sunlit patches of their host plants and can be seen nectaring on a variety of plants. (Iftner, et al., 1992; Nielsen, 1999; Shuey, 1995)
Communication and Perception
No social communication has been described in the literature. Undoubtedly there are courtship rituals that occur prior to mating, however, there is no published description. In addition, there may be some communication via pheremones as is found in other lepidopteran species.
- Other Communication Modes
Dukes' skipper larvae feed on Carex laucustris in the north and Carex hyalinolepis in the south. They are also reported to utilize Carex walteriana, and Rhynchospora. In Florida, the primary hostplant of E. dukesi calhouni has been identified as Rhynchospora inundata, but they are also known to utilize Rhynchospora miliacea and a species of Carex. (Glassberg, 1999; Opler and Krizek, 1984; Scott, 1986; Shuey, 1995)
Adults nectar on buttonbush Cephalanthus occidentalis, common milkweed Asclepias syriaca, swamp milkweed Asclepias incarnata, joe-pye weed Eupatorium maculatum, blue mistflower E. coelestinum, pickerelweed Pontederia cordata, hibiscus species Hibiscus, sneezeweed Helenium autumnale, alfalfa Medicago sativa, and red clover Trifolium pratense. (Iftner, et al., 1992; Nielsen, 1999; Opler and Krizek, 1984; Scott, 1986)
- Plant Foods
Predators of all life stages of butterflies include a variety of insect parasatoids. These wasps or flies will consume the body fluids first, and then eat the internal organs, ultimately killing the butterfly. Those wasps that lay eggs inside the host body include species in many different groups: Ichneumonidae, Braconidae, Pteromalidae, Chalcidoidea, Encyrtidae, Eulophidae, Scelionidae, Trichogrammatidae, and others. Trichogrammatids live inside the eggs, and are smaller than a pinhead. Certain flies (Tachinidae, some Sarcophagidae, etc.) produce large eggs and glue them onto the outside of the host larva, where the hatching fly larvae then burrow into the butterfly larvae. Other flies will lays many small eggs directly on the larval hostplants, and these are ingested by the caterpillars as they feed. (Scott, 1986)
Most predators of butterflies are other insects. Praying mantis, lacewings, ladybird beetles, assasin bugs, carabid beetles, spiders, ants, and wasps (Vespidae, Pompilidae, and others) prey upon the larvae. Adult butterflies are eaten by robber flies, ambush bugs, spiders, dragonflies, ants, wasps (Vespidae and Sphecidae), and tiger beetles. The sundew plant is known to catch some butterflies. (Scott, 1986)
Dukes' skippers most likely serve as minor pollinators. They are prey for a variety of predators.
- Ecosystem Impact
Economic Importance for Humans: Positive
Dukes skippers are considered uncommon to endangered in much of their range, and thus a subject of interest for nature enthusiasts, who travel and provide economic benefits to the communities they visit. The designation of the Dukes Skipper Sanctuary in Findley State Park in Ohio created a potential revenue source from park visitors. (Iftner, et al., 1992)
- Positive Impacts
- research and education
Economic Importance for Humans: Negative
There are no known adverse affects of Dukes' skipper on humans.
Dukes skippers are of conservation concern in all parts of their range, because they are only know from a few widely scattered sites. They are listed as threatened in the state of Michigan. (Iftner, et al., 1992; Nielsen, 1999; Opler and Krizek, 1984)
Dukes skippers were named in honor of W. C. Duke, who lived in Mobile, Alabama. Previous common names include scarce swamp skipper and brown sedge skipper. Dukes skippers were assigned to the genus Atrytone in 1923. (Opler and Krizek, 1984; Miller, 1992; Miller and Brown, 1981)
The species was discovered in Ohio in 1980 in Findley State Park, and led to the creation of the Dukes Skipper Butterfly Sanctuary by the Ohio Department of Natural Resources, the first of its kind in Ohio. (Iftner, et al., 1992)
Barb Barton (author), Special Contributors.
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.
a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.
uses smells or other chemicals to communicate
a period of time when growth or development is suspended in insects and other invertebrates, it can usually only be ended the appropriate environmental stimulus.
- active during the day, 2. lasting for one day.
humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
union of egg and spermatozoan
an animal that mainly eats leaves.
An animal that eats mainly plants or parts of plants.
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.
the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.
- internal fertilization
fertilization takes place within the female's body
marshes are wetland areas often dominated by grasses and reeds.
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
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.
an animal that mainly eats nectar from flowers
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
chemicals released into air or water that are detected by and responded to by other animals of the same species
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
- seasonal breeding
breeding is confined to a particular season
remains in the same area
offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.
reproduction that includes combining the genetic contribution of two individuals, a male and a female
a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
uses sight to communicate
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