Julia butterfly, Julia heliconian, Flame, Flambeau
Dryas iulia (often incorrectly spelled julia), commonly called the Julia butterfly, Julia heliconian, the flame, or flambeau, is a species of brush-footed (or nymphalid) butterfly. The sole representative of its genus Dryas, it is native from Brazil to southern Texas and Florida, and in summer can sometimes be found as far north as eastern Nebraska. Over 15 subspecies have been described.
Its wingspan ranges from 82 to 92 mm, and it is colored orange (brighter in male specimens) with black markings; this species is somewhat unpalatable to birds and belongs to the "orange" Müllerian mimicry complex.
This butterfly is a fast flier and frequents clearings, paths, and margins of forests and woodlands. It feeds on the nectar of flowers, such as lantanas (Lantana) and shepherd's-needle (Scandix pecten-veneris), and the tears of caiman, the eye of which the butterfly irritates to produce tears. Its caterpillar feeds on leaves of passion vines, including Passiflora affinis and yellow passionflower (P. lutea) in Texas.
Its mating behavior is complex and involves a prolonged courtship whose outcome appears to be controlled by the female. This raises questions pertaining to the occurrence of the evolution of sexual conflict.
The species is popular in butterfly houses because it is long-lived and active throughout the day. However, the caterpillars are spiky and may cause a skin rash.
Dryas iulia is characterized by elongated orange wings with black wing markings that vary by subspecies. Black markings are mainly located near the wing tips. Male Julia butterflies can be identified by their brighter orange color, compared to the duller orange exhibited by females. Images of many Julia butterfly subspecies can be found at the bottom of the page.
Dryas iulia is common in the tropical and subtropical areas of North, Central, and South America. In South America, throughout countries like Brazil, Ecuador, and Bolivia, the Julia butterfly is commonly distributed. The butterfly is also widespread throughout a number of the Caribbean islands, with endemic subspecies located in Cuba, Dominica, the Bahamas, and Puerto Rico, among others. Moving further north, the species can be commonly witnessed in Central America up into Texas and Florida (and can occasionally be found to move into the Nebraska area during the summer). The geographic distribution of D. iulia overlaps with the ranges of other butterflies which sometimes leads to conflict. For example, the ranges of D. iulia and the gulf fritillary overlap; in some cases, gulf fritillaries can sometimes be subjected to competition and fighting from Dryas iulia moderata when the two species have breeding populations in similar areas and within the same geographic range.
D. iulia prefer open, sunny breaks in the subtropical and tropical forests it inhabits. The butterfly is also common in open areas such as gardens, cattle grazing lands, and forest clearings, due to human impact. D. iulia can be found on a few main hostplants (or shrubs in Latin America) including the passion vine of the family Passifloraceae.
D. iulia flights take place throughout the year in southern Florida and southern Texas, but especially during the fall. The butterfly in its U.S. range has been seen to occasionally migrate as far north as Nebraska. However, south of its United States range, the Julia butterfly generally does not migrate. The butterfly's flight pattern can be fast or slow, and is usually seen around the middle story of their forest habitat.
Dryas iulia larvae feed on Passiflora plants almost exclusively, specifically those of subgenuses Astrophea (also known as Passiflora), Polyanthea, Tryphostemmatoides, and Plectostemma.
As adults, male and females feed differently based on their reproductive needs. As mentioned further down, males engage in mud-puddling behavior in order to gain valuable minerals for their spermatophores. They have also been seen to agitate the eyes of caimans and turtles in order to produce tears that the butterflies can drink. Observations of this from points 1500 km apart, were probably the first time scientific observations were coordinated via films broadcast on terrestrial television.
Females, meanwhile, besides visiting certain flower species for their nectar – like Lantana and Eupatorium (as both male and female D. iulia butterflies do) – also use pollen from flowers to gain nutrients needed for egg production.
Courtship behavior in Dryas iulia involves a very specific sequence of steps that can be categorized into three sequential phases: an aerial phase, an air-ground phase, and a ground phase. The observed courtship steps are outlined in detail below:
First, the male D. iulia approaches the female from behind. Then, the female takes flight, with the male flying in front of and above the female. This position is taken by the male so that the female can smell the male's scent scales and become sexually stimulated. Next, the female attempts to fly higher than the male, which can be seen as an anti-copulatory behavior, before landing. After that, the male D. iulia continues to beat his wings above and in front of the female, while both face the same direction. The female butterfly then opens and vibrates her hind wings and front wings. Her hind wings are fully opened while her forewings are only partially so. At the same time, the female emits scent glands from her raised abdomen. The male then beats his wings behind and then in front of the female once again. If the female is satisfied by the courtship, she lowers her abdomen and shuts her wings in preparation for mating.
Mating can occur within two weeks of the Julia butterfly's exit from the chrysalis. As adults, male D. iulia spend the majority of their time searching for females to mate with. Females of this butterfly species can mate four times in their lifetime, which is unusual for female Heliconius butterflies who generally mate just once.
Many mating behaviors in D. iulia are sex-specific, and can include receptive and non-receptive behaviors by the females of the species. Some female behaviors regarded as showing non-receptiveness include abdomen raising and overflight, in which the female attempts to fly higher than the male during the aerial phase of courtship. On the other hand, a female behavior such as shutting her wings has been found to be a key receptive behavior. For males, persistence did not seem to be a key driver of success, as behaviors performed by persistent males such as hovering over the female did not often lead to copulation.
The inability of persistent males – meaning, those that carried on extended courtship behavior – to increase copulation has led to researchers theorizing female copulation acceptance as the primary determinant of successful copulation in D. iulia. For example, the only male behavioral acts found to be indicative of successful copulation occurred in response to signals of female receptiveness.
When Dryas iulia are caterpillars, they can cause a skin rash on humans if touched. This is likely from the yellow liquid that is produced from the tips of the long, black spines that cover its body, which is emitted as a predator deterrent related to their cyanogenic glycosides
