A grasswing is a type of small butterfly that is found in parts of North America. Grasswings get their name from their habit of resting with their wings half-open in areas of tall grass and sedges. There are several different species of grasswings, each with unique features and behaviors.
What do grasswings look like?
Grasswings are small butterflies, with wingspans ranging from 1.5-3.5 cm. They have relatively long and slender wings compared to other butterflies. The upper sides of their wings are mostly brown, black, orange, and white. When they first emerge from their chrysalis, their wings are soft and pale. As their wings harden over several hours, the colors become brighter.
Here are some details on the appearance of common grasswing species:
- Common wood nymph: Light brown wings with large dark eyespots on the forewings and smaller eyespots on the hindwings. White bands line the edges of the wings.
- Northern pearly eye: Mostly dark brown wings with a large orange forewing spot and white bands around the edges. Iridescent spots give the hindwings a pearly effect.
- Southern pearly eye: Very similar to the northern pearly eye, but slightly smaller. Forewing spots may be more yellow than orange.
- Little wood satyr: Brown wings with orange bands near the edges and numerous small eyespots. Undersides are gray with irregular lines.
- Georgia satyr: Black wings bordered by broken orange bands. White specks stud the wings and a row of eyespots runs along the edges.
The undersides of grasswings wings tend to be lighter brown or gray, with markings that help camouflage them against bark and dead leaves when their wings are closed.
Where do grasswings live?
Different grasswing species are found in various parts of North America. Here is an overview of their geographic ranges:
- Common wood nymph: Throughout eastern North America, west to the Great Plains
- Northern pearly eye: From southern Canada south throughout the eastern U.S.
- Southern pearly eye: Southeastern United States
- Little wood satyr: Eastern U.S. from southern New England to Florida
- Georgia satyr: Florida, Alabama, and Georgia
These butterflies mainly live in wooded areas like forests, woodlands, and swamps. They prefer areas with some open spaces and plenty of shade. Depending on the species, they may be more abundant in hardwood forests, pine savannas, or cypress swamps.
What do grasswings eat?
Grasswings drink nectar from various woodland flowers with their long, narrow proboscis (tongue). Some favorite nectar sources include milkweeds, dogbanes, mints, and composites like coneflowers. They also drink from tree sap, rotten fruit, animal droppings, and mud puddles.
When they are larvae (caterpillars), grasswings feed on the leaves of grasses, sedges, and other plants. Each species specializes on one or several host plant species. For example, little wood satyr caterpillars feed on panic grasses while Georgia satyr larvae eat sedges and narrow-leaved grasses.
What is the grasswing life cycle?
Grasswings go through a complete metamorphosis with four basic stages:
- Egg – The female lays eggs singly on or near the host plant for that species. The egg hatches within about a week.
- Larva (caterpillar) – The caterpillar eats and grows through a series of molts where it sheds its skin. This stage may last several weeks.
- Pupa (chrysalis) – The caterpillar forms a chrysalis where it undergoes an incredible transformation into the adult butterfly. This can take one to three weeks.
- Adult butterfly – The adult butterfly emerges, its wings harden and it is ready to mate. Adults live for around 2-4 weeks.
The table below shows approximate grasswing development times at optimal temperatures:
Stage | Duration |
---|---|
Egg | 5-7 days |
Caterpillar | 3-4 weeks |
Chrysalis | 1-2 weeks |
Adult lifespan | 2-4 weeks |
Most grasswings have multiple broods per year. For example, common wood nymphs may have two to three generations from spring through fall. Species in warmer southern climates may breed year-round. The adults overwinter in sheltered spots and become active again in spring.
How do grasswings behave?
Grasswings exhibit some interesting behaviors and adaptations:
- They perch with their wings half-open to blend in with grasses and reeds.
- Males will patrol open areas seeking females and chase away competing males.
- Females exhibit picky behavior, only mating with certain patrolling males.
- Grasswings are fast, erratic fliers, making them hard to track.
- They roost communally at night, sometimes in large mixed-species groups.
- In cold weather, they may darken their wing colors to absorb more heat.
When threatened, grasswings may take off in fast, darting flights low to the ground. Or they may simply close their wings to disappear against the vegetation. Their small size and camouflage make them difficult for predators to catch once they settle back down.
Communication and courtship
Like many butterflies, grasswings locate mates through visual cues and pheromones. Males will patrol open sunny spots near woods, meadows, and streams. When a female flies by, the male will take off after her. He may chase and periodically bump her to assess if she is a suitable species and ready to mate.
Receptive females will slow down and allow the male to come alongside. He will flutter above her as they fly and mate in air. In some species like little wood satyrs, the male may produce pheromones from specialized wing scales to help attract females.
Migration
Most grasswing species do not undertake long seasonal migrations. However, some common wood nymphs populations are known to migrate moderate distances. For example, wood nymphs may migrate northward up to several hundred miles each spring from southern overwintering areas.
Wood nymphs have been observed migrating in mass numbers, sometimes joining mixed flocks with monarchs, painted ladies, and other butterflies. These migration events seem to be influenced by weather, food resources, and other factors.
What threats do grasswings face?
While some species like the common wood nymph remain relatively widespread, other grasswings face significant threats to their survival. Here are some of the main issues impacting grasswing butterflies:
- Habitat loss – Conversion of forests, prairies, and wetlands to farmland and development removes feeding and breeding areas.
- Pesticide use – Agricultural and residential pesticides can be toxic to larvae and adults.
- Invasive species – Non-native plants disrupt native ecosystems that grasswings rely on.
- Climate change – Changing temperatures, weather, and plant communities may affect grasswings.
- Light pollution – Artificial lights can disrupt navigation and mating behaviors.
Population declines have been particularly sharp in the southeastern U.S. where isolated wetland habitats have been heavily impacted. Several grasswing species like the Saint Francis satyr and Lotis blue are now federally listed as endangered.
How can grasswings be conserved?
Protecting existing grasswing habitats from development and degradation is the most vital conservation need. Other recommended actions include:
- Reducing pesticide use
- Managing invasive plants
- Creating natural buffers around wetlands and woodlands
- Planting native nectar plants
- Surveying populations to identify any declines
- Breeding rare species in captivity for reintroduction
- Controlling light pollution
Butterfly enthusiasts can also help by reporting grasswing sightings to inform conservation decisions. Providing clean water sources, limiting mowing, and creating backyard habitats can also support these delicate beauties.
Conclusion
Grasswings comprise a fascinating and diverse group of woodland butterflies in North America. While they can be elusive, a patient observer may catch a glimpse of these cryptic flutterers perching in a sunbeam or sipping at flowers. Protecting their fragile wetland and forest ecosystems will give grasswings the habitat they need to continue their beautiful cycles for generations to come.