Keel-necked firefly

Common Name

Keel-necked firefly, striped firefly

Scientific Name

Pyractomena ecostata

Recent Synonyms

None

Adult Male Size

11.5-16 mm

Diet

Snails, slugs, worms, and other soft-bodied invertebrates

Firefly Atlas Category

Focal species

The keel-necked firefly is found primarily in tidal marsh habitats within two disjunct regions, along the Gulf and Atlantic Coasts of Florida and in the Mid-Atlantic states of Delaware and New Jersey. The main threats to this species are habitat loss and degradation due to sea level rise, development, the spread of invasive plants, and artificial light at night.

Identifying Features

Pyractomena fireflies can be distinguished from other flashing firefly genera in North America by their roughly pentagonal-shaped pronotum (head shield) which features a raised keel down the midline. The body posture in Pyractomena is flat, unlike the hunched posture of Photuris fireflies. In female Pyractomena, the light organs are limited to the outer hind corners of the abdominal segments. The male lanterns each have two punctures called stigmatiform pores. Pyractomena ecostata is a relatively large firefly. It has an elongated and narrow form. The diagonal yellow stripes on the elytra (wing covers) are a distinctive and diagnostic trait. The antennae are noticeably short. Examining the aedeagus (male genitalia) is not necessary for identification of specimens of this species.

Conservation

Reason(s) For Firefly Atlas Focal Species Designation

Reliably identifiable, Suspected population loss

Status

IUCN Red List

The International Union for Conservation of Nature (IUCN) Red List of Threatened Species is an inventory of the global conservation status and extinction risk of biological species, maintained collectively by scientists worldwide.

Vulnerable (VU)

NatureServe

The NatureServe conservation status ranks use a standardized methodology to assess the extinction risk of species, with a focus on the US and Canada. State wildlife agencies and natural heritage programs use these ranks to prioritize species for conservation actions.

Globally vulnerable (G3) Imperiled to vulnerable in Florida (S2S3) State rank not yet assessed in Alabama, Delaware, New Jersey (SNR)

Species of Greatest Conservation Need Lists

Species of Greatest Conservation Need (SGCN) are lists of species included in State Wildlife Action Plans, identifying animals and plants that need the most conservation attention and resources at the state and region level.

Delaware

US Endangered Species Act

The Endangered Species Act is a United States law that provides legal protections to species that are officially listed as endangered or threatened by the US Fish and Wildlife Service.

N/A

Threats

Habitat loss and degradation due to sea-level rise, development, the spread of invasive plants, and artificial light at night are the main threats to this species.

Location

Distribution

USA

Alabama, Delaware, Florida, Maryland, New Jersey

Details

The keel-necked firefly is known from two geographically separated regions: coastal areas of Alabama and Florida, and coastal marshes of Delaware, Maryland, and New Jersey.

Habitat

This firefly is found mostly in brackish tidal marshes near the Gulf Coast or Atlantic Ocean. However, it has also been found in low-lying wet pastures along highways in Florida, so it is not restricted to habitats with saltwater intrusion.

Behavior

Activity Period

In the southern part of its range, adults of this species are seen flying from April to September.

Flash Pattern

Males emit bright green explosive courtship signals, about a 0.5 to one second in duration, every 5 to 20 seconds or so, as they fly over their marshy habitat.

Sources

Heckscher, C. and A. Walker. 2021. Pyractomena ecostata. The IUCN Red List of Threatened Species 2021: e.T164044862A166771368. https://dx.doi.org/10.2305/IUCN.UK.2021-1.RLTS.T164044862A166771368.en. Accessed on 25 September 2025. Heckscher, C. and A. Walker. 2021. Pyractomena ecostata. NatureServe Explorer. https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.1215529/Pyractomena_ecostata. Accessed on 25 September 2025.