Improved evening porch-sitting conditions are a huge perk of moving back east. As daytime temperatures shift to borderline intolerable, the days of being able to sit outside after dark with only shorts and a t-shirt begin in earnest. These lovely evenings contrast starkly with the west coast. In California and Oregon, it could be 100 degrees out in the afternoon, but as soon as the sun sets, sweatshirt are required.
Beyond the cool temperatures, Western evenings also suffer from a dearth of fireflies. That’s not to say there are no species at all. Around 20 of the 179 known species and subspecies of beetle in the family Lampyridae native to the United States can be found in the Pacific States. Here’s a picture of Photinus californicus (California glowworm) I took last year in the northern Sierra.
However, fireflies in the West are nowhere abundant, and they basically never put on a dramatic light show. All fireflies glow as larvae. However, within the Lampyridae, there are three styles of courtship that differ in their use of light. In “glowworms”, only the flightless females produce glow that non-glowing males fly towards. In a second group, the “dark fireflies”, both sexes lose their ability to glow as adults. These species fly during the day and use pheromones to find mates, like most other species of beetle do. Here’s a Lucidota atra (black firefly) that I found today in my house.
I also found Photinus corruscus (winter firefly) while we were in Acadia National Park last week.
While glowworms and dark fireflies occur in the west, the third strategy is unfortunately absent. These are the classic “lightning bugs”, where both males and females glow. Males will fly around blinking a specific pattern, to which the females will respond. Here’s the most common lightning bug across much of the East, Photinus pyralis.
The males of this species light up for a second or so, while moving in an upward J from a couple feet above the ground. Other species will differ in the rate, length, location, flight pattern, and even color of the flash. For example, in the Appalachians of Carolina, the Phausis reticulata glows with a long, eerie bluish light. Perhaps most spectacularly, in Photinus carolinus, another Appalachian species, all the males in an area will blink in synchrony.
While the four pictured species are common, unfortunately, many species of fireflies are in trouble. Those evenings of porch sitting aren’t as wondrously lit as they used to be. The culprits are the same ones that are leading to the general global decline in insects—pesticides, habitat loss, changes in weather patterns, and the increase of artificial lights. One of the species in trouble is the state insect of Pennsylvania, Photuris pensylvanica. Like other members of its genus, this species is predatory. Female Pennsylvania fireflies blink the code of a Photinus female, luring in an unsuspecting male in to eat. Unfortunately, least according to the records in iNaturalist, the Pennsylvania firefly no longer occurs in Pennsylvania, and is making its last stand in a few scattered locations on the Delmarva Peninsula.
To at least track the decline, and hopefully aid in making some conservation decisions, there are some great citizen science projects centered around fireflies. The firefly atlas https://www.fireflyatlas.org/, is looking to collect distribution, phenology, and habitat data on all species of fireflies, but they are focused in particular on a few threatened and data deficient species. Locally, Photuris forresti (the loopy five firefly) is a target. Additionally a group of local entomologists are interested recruiting folks to help document a currently undescribed species of Phausis in the North Carolina around the Research Triangle that they are calling the Piedmont Ghost (https://carolinaghosthunt.wordpress.com/). I’m pretty excited to get involved in these efforts and find more species of these amazing beetles.
botanicalramblings 