19-3-2017 MIAMI, FLORIDA - ZEBRA LONGWING BUTTERFLY (Heliconius charithonia)

Although H. charithonia is to some extent static, maintaining a home range, adults do move between territories. Butterflies with Mexican origins migrate north into Texas, following the retracting temperature gradient. Rainfall has no effect on migration patterns. Arrival dates and duration of stay depend on the distance traveled: the longer the distance traveled, the shorter the duration of stay.

Roosting to deter predators

Adults roost in groups of up to 60 individuals on a nightly basis, returning to the same roost every night. These roosts provide protection to adults, the large groups deterring predators and retaining warmth. Solitary individuals, or very small roosts, avoid exhibiting proper warning signals so as not to attract predators. Pre-roosting interactions, which consist of sitting near one another, chasing each other briefly while fluttering, or basking, occur between butterflies from separate roosts, indicating that the butterflies are aware of other roosts in their home range. Despite this, the zebra longwing chooses to form smaller aggregations. The optimal roost size for predator deterrence is five individuals; roost size is also influenced by resource availability and foraging. H. charithonia roosts to display collective aposematism, deterring predators by conspicuously advertising their unpalatable taste.

H. charithonia adults form communal roosts nightly. Communal roosting occurs when individuals aggregate at a particular site for more than a few hours. Roosting begins as early as three hours before sunset and usually ends within two hours after sunrise. Since roosting is at night, adults need to be able to see at low light levels to locate roost sites, either when looking for twigs, tendrils, and dry leaves to land on to start a roost, or when searching for conspecifics that are already roosting. Their eyes also help them to recognize color patterns in conspecifics. UV rhodopsins in the eye help them to distinguish between 3-OHK yellow pigments, or ultraviolet colors, and other yellow pigments, which to the human eye is indistinguishable. At shorter distances, the butterflies recognize conspecifics via chemical cues. These chemical cues include volatile and nonvolatile substances. The significance of this chemical communication remains largely unknown for Heliconius in general. However, in H. melpomene, (E)-?-ocimene was found to attract males and females in diurnal situations.

At eclosion, the ratio is highly female biased, but the rest of the year the sex ratio is overall male biased (68% males). This is because males typically stay near their natal sites to find a mate, while females move around to find oviposition or feeding sites on Passiflora plants. Because females are very mobile, males rarely mate with relatives, and inbreeding rates are very low.

26-3-2017 RANCHO NATURALISTA - ZEBRA LONGWING BUTTERFLY (Heliconius charithonia)

Heliconius charithonia, the zebra longwing or zebra heliconian, is a species of butterfly belonging to the subfamily Heliconiinae of the family Nymphalidae. It was first described by Carl Linnaeus in his 1767 12th edition of Systema Naturae. The boldly striped black and white wing pattern is aposematic, warning off predators.

The species is distributed across South and Central America and as far north as southern Texas and peninsular Florida; there are migrations north into other American states in the warmer months.

Zebra longwing adults roost communally at night in groups of up to 60 adults for safety from predators. The adult butterflies are unusual in feeding on pollen as well as on nectar; the pollen enables them to synthesize cyanogenic glycosides that make their bodies toxic to potential predators. Caterpillars feed on various species of passionflower, evading the plants' defensive trichomes by biting them off or laying silk mats over them.

The zebra longwing, Heliconius charithonia (Linnaeus),was designated the state butterfly of Florida in 1996.  However, mass spraying of naled has decimated the zebra longwing population in Miami-Dade County, Florida. There has been mass collapse of the colonies with impacts on the balance of the ecosystem.

The caterpillars are white with black spots and have numerous black spikes along their body. Adult butterflies are monomorphic of medium size with long wings. On the dorsal side, the wings are black with narrow white and yellow stripes, with a similar pattern on the ventral side, but paler and with red spots. The wingspan ranges from 72 to 100 mm.

H. charithonia is found in South America, Central America, the West Indies, Mexico, south Texas and peninsular Florida. Adults sometimes migrate north to New Mexico, South Carolina, and Nebraska during the warmer months. The geographic distribution of H. charithonia overlaps with the ranges of other butterflies which sometimes leads to conflict. For example, the ranges of H. charithonia and the gulf fritillary overlap; in some cases, gulf fritillaries can sometimes be subjected to competition and fighting from Heliconius charithonia vazquezae when those species have breeding populations in similar areas and within the same geographic range. It was declared the official butterfly for the state of Florida in the United States in 1996. The species frequents tropical hammocks, moist forests, edges, or fields.