Dryas iulia

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 drinks 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. Images of many Julia butterfly subspecies can be found at the bottom of the page.

Distribution

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).

Habitat

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. 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.

Hostplant coevolutionary strategies

Passiflora vines and D. iulia (among other Heliconian butterflies) have shown strong evidence of coevolution, as the butterflies attempt to gain better survival for their laid eggs and the plants attempt to stop their destruction from larval feeding. Many members of the genus Passiflora have evolved to produce very tough, thick leaves that are hard to break down by caterpillars. Some Passiflora vines have gone further by producing small leaves that look like a perfect place for the butterflies to lay eggs but break off at the stem within a few days, carrying the D. iulia eggs with them. Other Passiflora vines actually mimic eggs of the butterfly species that use it as a hostplant, so that a passing butterfly thinks the plant already has eggs on it and consequently does not oviposit. The butterflies have thus evolved to be more discerning in their egg placement, and better able to detect strategies used by their host plant, the Passiflora

Mud-puddling behavior

Mud-puddling is a peculiar social behavior engaged in by a number of butterfly species, including D. iulia. It involves male butterflies crowding around damp ground in order to drink dissolved minerals through a process of water filtration. During copulation, the male butterfly uses minerals in his spermatophore, which must be replenished before the following mating. When a male finds a suitable spot for the behavior, other males can quickly join and hundreds of butterflies may become attracted to the site. Multiple species may join the group, but the butterflies do not evenly distribute between species. Instead, D. iulia and others usually remain near members of their own species.

Protective coloration

Dryas iulia butterflies are part of the "orange" Müllerian mimicry complex, one of the similar Heliconian species that employ this protective tactic. Passifloracae, the primary food source of D. iulia caterpillars, contains trace amounts of cyanide. This has led to the development of cyanogenic glycosides that make the butterfly unpalatable to its predators, which come from a mixture of storage from their hostplant and larval synthesis. The mimicry in D. iulia involves other butterfly species having evolved to look similar to the Julia butterfly in order to convey their presumed unpalatability. thumb|D. iulia caterpillar with spikes

Life history

Egg

Dryas iulia eggs tend to be a light yellow color when laid, which turns to a darker orange or brown shade before hatching. Each of the butterfly's eggs are separately laid onto new leaf tendrils of its host plant, usually the passionflower vine. 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. They feed on invasive Passiflora species around its invasive range, usually Passiflora suberosa and sometimes Passiflora foetida.

Subspecies

Listed alphabetically:

D. i. alcionea (Cramer, 1779) – (Suriname, Bolivia, Brazil)
D. i. carteri (Riley, 1926) – (Bahamas)
D. i. delila (Fabricius, 1775) – (Jamaica)
D. i. dominicana (Hall, 1917) – (Dominica)
D. i. framptoni (Riley, 1926) – (St. Vincent)
D. i. fucatus (Boddaert, 1783) – (Dominican Republic)
D. i. iulia (Fabricius, 1775) – (Puerto Rico)
D. i. largo (Clench, 1975) – (Florida)
D. i. lucia (Riley, 1926) – (St. Lucia)
D. i. martinica (Enrico & Pinchon, 1969) – (Martinique)
D. i. moderata (Riley, 1926) – (Mexico, Honduras, Ecuador)
D. i. nudeola (Bates, 1934) – (Cuba)
D. i. warneri (Hall, 1936) – (St. Kitts)
D. i. zoe (Miller & Steinhauser, 1992) – (Cayman Islands)

Dryas iulia alcionea MHNT.jpg|D. i. alcionea – MHNT

Dryas iulia dominicana MHNT.jpg|D. i. dominicana MHNT

Dryas julia caterpillar.JPG|Caterpillar

Dryas julia (A. Machado).jpg| D. i. alcionea Brazil

Julia (Dryas iulia titio).JPG| D. i. alcionea Brazil

Julia (Dryas julia titio) underside.JPG| D. i. alcionea Brazil

Julia butterfly (Dryas iulia delila) female J.JPG|D. i. delila female, Jamaica

Julia butterfly (Dryas iulia iulia) male.JPG|D. i. iulia male, Trinidad

Julia (Dryas iulia moderata).jpg|D. i. moderata Panama

Julia (Dryas iulia moderata) underside.jpg|D. i. moderata Panama

Julia (Dryas iulia nudeloa) male.JPG|D. i. nudeola male, Cuba

Julia (Dryas iulia nudeloa) female.JPG|D. i. nudeola female, Cuba

Julia (Dryas iulia zoe) male.JPG|D. i. zoe male, Grand Cayman

Julia (Dryas iulia zoe) male underside.JPG|D. i. zoe male, Grand Cayman

Julia (Dryas iulia zoe) female.JPG|D. i. zoe female, Grand Cayman

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