Endangered Rare Species of Butterflies

Topics: Butterfly


The Regal fritillary (Speyeria Idalia) is a member of Nymphalidae, the brush-footed butterflies. It has a wingspan of 67 to 105 mm. A reddish orange colored butterfly, the Regal fritillary is a sexually dimorphic species. The upperside forewing of both sexes is a reddish orange color with black markings, while the hindwing is a velvety black with two rows of spots. The female’s spots are cream-colored and the male sports rusty orange outer set of spots and cream-colored inner spots.

The Regal fritillary is currently found from eastern Montana, Wyoming, Colorado, the Dakotas, Nebraska, Minnesota, Kansas, Iowa, Missouri, and Illinois in mostly tall-grass prairie remnants and a single colony in Pennsylvania at Fort Indiantown Gap-National Guard Training Center.

However, the Regal fritillary’s range use to be much larger, going from eastern Montana to Maine, down to Arkansas and across to Virginia. As stated before, the Regal fritillary is mostly found in tall-grass prairie remnants but also is found in meadows, marsh, mountain pastures, and other sunny locations.

The adult butterflies flight period is from mid-June to mid-August in some areas. After mating, the female Regal Fritillary will enter a diapause, a suspended development for six to eight weeks. In early August, a juvenile development hormone sharply increases and the ovaries develop. Once the ovaries develop, the eggs are fertilized and then the eggs are oviposited. The female Regal fritillary lays approximately 1,000 to 2,500 eggs in leaf litter, on pebbles and really anywhere. In fact, Regal fritillary has one of the highest egg counts in lepidopteran.

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When the eggs hatch, the larvae immediately head for leaf litter to overwinter. Once spring rolls around the caterpillars emerge to feed on violets until they pupate in late May. The adults nectar on milkweed, thistle, coneflower, blazing-stars, and various others.


The biggest threat to the Regal Fritillary is the loss of its habitat. The tall-grass prairie that the Regal fritillary resides is disappearing at a rate of 53 million acres every year according to the World Wildlife Fund. Most of those acres are being converted into cropland. In fact, only 366 million acres of the Great Plains are left. This conversion of tall-grass prairie into row crops is what has had the most historical impact on the Regal fritillary (Shelby 2007). And it is not only the conversion of tall-grass prairie to cropland way that the Regal fritillary is losing its habitat. Urban development and housing construction, road construction and maintenance, gravel mining, and wind generators are other ways that the Regal fritillary is losing its habitat (Shelby 2007).

However, the remaining prairie and prairie restorations that are left for the Regal fritillary also have many problems too. One of the main problems, are the management practices for protecting the prairie. Historically fires can be beneficial to many plant species and the prairie ecosystem. However, prescribed burns are often conducted in early spring when the first instar larvae are the most vulnerable. These prescribed burns can even kill the overwinter larvae, which can have a drastic effect on the Regal fritillary population the following year (Moranz et al 2014). Burning large portions of prairie has extirpated Regal fritillary populations (Powell et al 2007). In some cases, the use of rotational burning of 30 ha or less has led to an extremely sharp decrease of Regal fritillary (Swengel and Swengel 2001). But fire is important to the health of the prairie ecosystem. In recent years, the prairie ecosystem is being invaded by Smooth brome (Bromus inermis) Kentucky bluegrass (Poa pratensis) and woody plants that is transforming prairie into a monoculture or woodlands. Both of these ecosystems are not suitable for the grassland-obligates such as the Regal fritillary.

A second problem for the Regal fritillary comes from pesticides used on/in the row crops. The pesticide Bt, from the bacterium Bacillus thuringiensis, is used to control Gypsy moths (), however, it has been shown to be lethal to all lepidopteran larvae (Shelby 2007). This type of exposure to Bt is usually found in areas where forest is next prairie grasslands, like in Ohio and other eastern portions of the Regal fritillary’s range. There have been concerns raised about the pollen from Bt corn contaminating milkweed, a plant that is not only used by the Regal fritillary but the Monarch butterfly as well (Shelby 2007). However, Shelby did suggest that further studies are needed. The indiscriminate spraying of pesticides is also a problem for the Regal fritillary and other prairie specialist butterflies in areas that their prairie habitat is adjacent to crop land (Shelby 2007). To quote Shelby 2007: “broadcast spraying usually targets dicots, can also effect Regal fritillary populations indirectly by eliminating the larval food plants and important nectar sources”.

Another problem for Regal fritillaries is the weather conditions that effect the population year-round. The first instar larvae are extremely vulnerable to cold weather like late winter storms and hard frosts. Other weather conditions that can affect the first instar and cold, wet conditions. These conditions affect the first instar by preventing it from developing at the rate it needs to (Shelby 2007). During the adult flight periods, severe storms can kill off many of the adults with the harsh winds, and the cold, damp, overcast conditions and the rain can limit reproduction by reducing the adult activity (Shelby 2007).

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Endangered Rare Species of Butterflies. (2021, Dec 31). Retrieved from https://paperap.com/endangered-rare-species-of-butterflies/

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