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Image Credit: Alex B.
Summer evenings are made brighter by the Pennsylvania Firefly, but that doesn't mean better for every male firefly in the area.
On dry summer nights, the Pennsylvania Firefly emits a yellow-green glimmer of light every few seconds. The light comes from an enzyme called luciferase and produces virtually no heat. The ability for a living organism to produce light is called bioluminescence. This flashing light signal is meant to attract members of the opposite sex. If a pair successfully finds each other, they mate and a population continues to exist in that area. Sometimes, and deliberately, the female's signal attracts members of a different genus. Careless males from the genus Photinus find this a costly mistake. If males respond and approach females from the Photuris genus, they are killed and eaten by the female. Consuming the males allows the females to absorb a steroid naturally found in the Photinus males. Females that had high levels of this steroid, lucibufagin, in their own system became less appetizing to jumping spiders that attacked them. One small taste of lucibufagin was enough to deter the jumping spider from continuing to attack or eat the female. Longer life means more opportunities to reproduce, so the mimicry pays off for the whole Pennsylvania Firefly species.
Pennsylvania Fireflies look similar to Big Dipper Firefly. An easy way to differentiate them is by examining the elytra (the black wing coverings). Pennsylvania Fireflies have a thin stripe of orange or yellow that stretches from the 'shoulder' down to the bottom of the elytra. The dome-shaped thorax (shoulder plate) is yellow around the edges and has a black mark in the center with two red spots on either side of it.
This species of firefly eats other insects in addition to the males of Photinus. Smaller bugs, snails and worms also comprise its diet. This particular species has been named the state insect of Pennsylvania.
Scientific Name: Photuris pensylvanica
Size (Adult; Length): 8mm to 10mm (0.31in to 0.39in)
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Antennae: Beetles have a pair of antennae on the head used as sensors.
Head: The head is home to the insect's eyes, antennae, and mandibles (jaws).
Thorax: Holds the three pairs of legs as well as vital internal organs.
Elytron: One of two wing cases on a Beetle that protects its wings (plural: elytra).
Wings: Appendages used for flying and kept under the elytra until needed.
Abdomen: Houses organs related to circulation, reproduction, and excretion.
Legs: Beetles have three pairs of legs located at the thorax, numbering six legs in all.