Critter Catalog

What do they look like?

Uncas skippers are small butterflies at 28 to 34 mm long, with a thick body. They measure 3.1 to 3.81 cm from wing tip to wing tip. The bottom of their wings are white with dark brown or black markings and spots. Like all skippers, Uncas skippers have short antennae with clubbed ends and tips that curve backwards.

Males and females have very different colors and patterns on the upper side of their wings. Males have a brownish-orange color, with small light spots. Males also have a black band of scent scales on their wings. Females are darker in color than males, with large white spots on the front wings. Females also have larger, broader wings. Both sexes become duller with age as the scales on their wings fall off, but the pattern will stay the same.

The eggs are greenish white. The young larvae or caterpillar is pale brown, and the head is a darker brown with cream spots and streaks in the front. (Coffin and Pfannmuller, 1988; Glassberg, 2001; "Hesperia uncas", 2014; Opler, 1999)

• Other Physical Features
• ectothermic
• heterothermic
• bilateral symmetry

• Sexual Dimorphism
• female larger
• sexes colored or patterned differently
• ornamentation

• Range length

  28 to 34 mm

  1.10 to 1.34 in

• Range wingspan

  3.3 to 3.81 cm

  1.30 to 1.50 in

Where do they live?

The Uncas skipper, Hesperia uncas, is found across Canada from Saskatchewan to Alberta, and down into the United States through the Rocky Mountains and Great Plains. From the Great Plains it lives as south as Texas and New Mexico. In New Mexico and Minnesota, there are two populations that are completely separated from the rest of the country. (Coffin and Pfannmuller, 1988)

• Biogeographic Regions
• nearctic
  • native

What kind of habitat do they need?

Uncas skippers can be found in grasslands. Some western populations can be seen gathered in large numbers on thistle plants in southwestern road ditches. (Brock, 2003; Garth and Tilden, 1986; Glassberg, 2001)

• These animals are found in the following types of habitat
• temperate
• terrestrial

• Terrestrial Biomes
• desert or dune
• savanna or grassland

• Other Habitat Features
• suburban

• Range elevation

  989 to 8100 m

  3244.75 to 26574.80 ft

• Average elevation

  5500 m

  18044.62 ft

How do they grow?

Uncas skippers have four life stages: egg, larvae (also called a caterpillar), pupae, and adult. This is called complete metamorphosis. Adults mate in the spring or summer and lay eggs. The eggs hatch after 10 days. Caterpillars go through several developmental stages called instars, become pupae, and transform into adult butterflies. These butterflies mate and lay eggs, but when these caterpillars hatch and reach their fourth or fifth instar stage, they go into hibernation for the winter, and do not come out of hibernation until the following spring. In the spring, they become pupae for 2 to 3 weeks, and then adults, and repeat the entire life cycle. There are some parts of their range, like in Minnesota, where the Uncas skippers only have one generation per year, meaning that they only lay eggs once per season, and the caterpillars that hatch from this first batch go into hibernation. ("Hesperia uncas", 2014; "Hesperia uncas", 2014)

• Development - Life Cycle
• metamorphosis
• diapause

How do they reproduce?

Female Uncas skippers probably mate right after they emerge from pupation in the spring. Males will look for female mates by perching on plants or on the sand. Many males will also collect on hills or ridges, which may get the attention of the female. Males also produce chemicals called pheromones from the scent scales on their wings. These pheromones attract the females. When they want to mate, females will fly down to where the males are sitting. Females usually only mate once in their lives, while males will mate with many different females. ("Hesperia uncas", 2014)

• Mating System
• polygynous

Depending on the area, Uncas skippers can go through their entire life cycle once or twice a year. In South Dakota and most of its range, there are two generation per year, with adults present from May to June and July to September. In Minnesota, there is one generation per year from June to July. After mating, the female finds plants to lay her eggs on, usually a kind of grass called the hairy grama (Boutelous hirsute). The female will lay only a single egg before moving on to the next tuft of grass. (Glassberg, 2001; "Hesperia uncas", 2014)

• Key Reproductive Features
• semelparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
  • internal
• oviparous

• How often does reproduction occur?

  Females mate once in their lives, while males will mate as much as possible.

• Breeding season

  Depending on the region, mating takes place from late spring to late summer.

Females provide nutrients in their eggs for the young to use to grow and develop. Female parents also lay the eggs on specific grass plants so that the caterpillars will have something to eat when they hatch. However, after the eggs are laid, the parents leave and do not come back. ("Hesperia uncas", 2014; "Hesperia uncas", 2014)

• Parental Investment
• pre-hatching/birth
  • provisioning
    • female

How long do they live?

Uncas skippers live for about 3 weeks after emerging from pupation as adult butterflies. ("Hesperia uncas", 2014)

• Average lifespan
  Status: wild

  21 days

How do they behave?

The larvae will live in shelters that grow in size, that they themselves built out of silk and plant materials. The shelters are built bigger and bigger as the larvae grow too. Overwintering larvae have also been found in shelters that have been build under the soil. Adult Uncas skippers are very rapid and strong fliers. They have a very fast wing beat that almost appears to be like a blur to human eyes. ("Hesperia uncas", 2014)

The caterpillars build shelters by tying together leaves and other plant pieces with silk. They live in these shelters and build bigger shelters as they grow. Caterpillars that are hibernating for winter have been found in shelters buried in the soil. Adult Uncas skippers are very strong, fast fliers. Their wings beat so fast that they often look like a blur to human eyes. ("Hesperia uncas", 2014)

• Key Behaviors
• flies
• motile
• sedentary
• hibernation

How do they communicate with each other?

Male Uncas skippers have a black line of scent scales on their wings. While trying to attract mates, males produce pheromones from these scent scales. The pheromones let the female skippers know that the males are there and ready to mate, and attract the females to them. Males also communicate with females by sight. The males gather in groups on high ridges, which females see and know that the males are there to mate. ("Hesperia uncas", 2014)

• Communication Channels
• visual
• chemical

• Other Communication Modes
• pheromones

• Perception Channels
• visual
• chemical

What do they eat?

Uncas skipper caterpillars only eat certain kinds of grasses. These grasses are mostly blue grama (Bouteloua gracilis) grass and hairy grama (Bouteloua hirsute). Adults feed on nectar from many different flowers, but prefer to feed from golden aster (Heterotheca villosa) and hairy puccoon (Lithospermum caroliniense). (Coffin and Pfannmuller, 1988; "Hesperia uncas", 2014)

• Primary Diet
• herbivore
  • folivore
  • nectarivore

• Plant Foods
• leaves
• nectar

What eats them and how do they avoid being eaten?

There is not much known about what animals prey on Uncas skippers. As quick fliers, they are likely able to fly away and escape from many predators. ("Hesperia uncas", 2014)

What roles do they have in the ecosystem?

Uncas skippers feed on flowers nectar. While they move from flower to flower, they also help to pollinate these flowers, which allows the plants to reproduce. ("Hesperia uncas", 2014)

• Ecosystem Impact
• pollinates

Do they cause problems?

Uncas skippers do not cause any problems for humans.

How do they interact with us?

Uncas skippers do not have any positive effects on humans.

Are they endangered?

In Minnesota, Uncas skippers are considered an endangered species. This is because their grassland habitats in the state of Minnesota have been destroyed by people. Since this does not leave much area for Uncas skippers to live in, their population size has gotten much smaller. People are trying to protect the land that the skippers live on to prevent them from disappearing from Minnesota. In the rest of the country, Uncas skippers are just fine and are not an endangered species. ("Hesperia uncas", 2014)

• IUCN Red List

  Not Evaluated

• US Federal List

  No special status

• CITES

  No special status

Contributors

Courtney Christensen (author), Minnesota State University Mankato, Robert Sorensen (editor), Minnesota State University, Mankato, Angela Miner (editor), Animal Diversity Web Staff.

References

Minnesota Department of Natural Resources. 2014. "Hesperia uncas" (On-line). Species Profile: Minnesota DNR. Accessed April 16, 2014 at http://www.dnr.state.mn.us/rsg/profile.html?action=elementDetail&selectedElement=IILEP65010.

Brock, J. 2003. Kaufman Field Guide to Butterflies of North America. New York, United States of America: Houghton Mifflin Company.

Coffin, B., L. Pfannmuller. 1988. Minnesota's Endangered Flora and Fauna. Canada: University of Minnesota Press. Accessed March 26, 2014 at http://mnsu.summon.serialssolutions.com/?s.q=uncas+skipper#!/search?ho=t&q=uncas%20skipper&l=en.

Garth, J., J. Tilden. 1986. California Butterflies. United States of America: University of California Press.

Glassberg, J. 2001. Butterflies Through Binoculars. New York, United States of America: Oxford University Press, Inc..

Holland, J. 2003. Field Guide to Butterflies. Canada: Sterling Publishing Co, Inc..

Opler, P. 1999. A Field Guide to Western Butterflies. New York: Houghton Mifflin Company. Accessed April 21, 2004 at http://books.google.com/books?id=ilL_XX1rbNoC&pg=RA2-PT360&dq=Holland+field+guide+to+butterflies&hl=en&sa=X&ei=MeJVU5y7HNGKyATKjYKIAw&ved=0CEQQ6AEwAg#v=onepage&q=uncas%20skipper&f=false.