Firefly Fancy

Firefly Fancy
shared by Melissa Donahue, Naturalist 
melissa.donahue@nashville.gov
Late May 2020

The light is fading behind the hackberry tree in the backyard.  I am sitting on my back porch with a soft head on my shoulder.  Whispering quietly, we are settling down for one of my favorite early summer activities with some of my favorite people.  The day has been warm, but the night is pleasant and not muggy.  We peer into the night with great anticipation.  We, my husband and two grandchildren and I, are looking for the first firefly of the evening. 

There are 25 species of fireflies in Tennessee with Photinus pyralsis being the most familiar.  At least 19 of these species are found in the Great Smoky Mountains.  Our plan was to be camping in the Great Smoky Mountains this year.  The main attraction this time of year is the synchronized fireflies near the Elkmont campground.  This species, Photinus carolinus, is the only species in America whose individuals can synchronize their flashing light patterns. 

Check out this video of the Smoky's synchronized fireflies

Fireflies (or lightning bugs) are not flies or true bugs, but a beetle in the family Lampyridae.  They take from one to two years to mature from larvae. A few days after mating the female lays her eggs on or just under the soil.  In 4 weeks, the larvae will emerge. In this larval stage, this insect lives underground for one to two winters and feeds on snails and smaller insects. They are avid hunters, injecting their prey with a paralytic substance before consuming it.  Most fireflies pupate underground or in rotting logs, although some attach to tree trunks and emerge in early spring or summer when the temperature and rainfall are just right. 

An adult firefly is about 2 cm long.  Different species eat different things: some eat nectar, other insects or nothing at all. Some species of fireflies feed on other fireflies—most notable is the genus Photuris, which mimics female flashes of Photinus, a closely related species, to attract and devour the males of that species.

Each species of firefly has a characteristic flash pattern. Called bioluminescence, it occurs when oxygen and the organic compound luciferin react together in the presence of the enzyme luciferase. This creates a “cold light” that uses 100% of the energy to produce light, and therefore no heat is produced.  This light is usually greenish-yellow but can be other colors, including one species that produces a bluish light. This allows the insects to flash.  The flashes help the male and female communicate, mark territory and warn away predators.  The males flash about every 5 seconds and the females flash about every two.  In most species, the female waits in the grass or on trees and shrubs while the male flies and flashes. When an attractive male appears, she will signal with a flash of her own.

photo credit Cosmos magazine

Just as the final light fades, we see our first flash.  Awed, we sit in a hushed quiet while flashes of lights rise up from the grass and bushes.  Then we grab our jars with holes in the lids and, laughing, head into the yard to catch our night lights.  We carefully observe the beetles, and then let them fly away and head to bed.

Life in the Soil

Shared by Kim Bailey
Naturalist at the Nature Center
kim.bailey@nashville.gov
Photos credit Kim Bailey unless otherwise noted

Spring is the time of year I most enjoy gardening. When the songs of migrating birds aren’t distracting me, I turn my attention to the greening trees and emerging plants and sink my hands into the soil. And being the critter lover that I am, I always look forward to the surprises that I inevitably uncover as I dig.   

Some years ago, I began to appreciate soil for what it is: a rich and varied habitat as diverse as its inhabitants. All those air spaces between the soil particles are filled with animals that range from microscopic nematodes feeding on bacteria, fungi and each other to the incredibly adaptive, shovel-pawed mole who moves through its landscape like a swimmer in water! Once I saw a mole emerge from a hole in the ground, run across the driveway, and dig a new hole in a matter of seconds. He literally disappeared before I could finish yelling “look at the mole”! I have respected the power of his front feet ever since. No photo proof of that quick encounter! 

However, over the years I have found some interesting animals that did allow me to photograph them. I have been entertained by both a crayfish and an American toad poking out of holes in the ground. 

Crayfish burrows extend deep into the soil where it is moist.

Chimneys like this are a sign that crayfish are nearby. 
Photo credit Science Photo Library via Google Images

American toads spend most of their lives on land and sometimes burrow into soil to stay moist.  

Have you ever found an obvious hole or space extending beneath the surface of the ground? I mistakenly dug this Trapdoor spider up, destroying her carefully constructed home in the process.  

Trapdoor spiders live in burrows underground. At ground level they construct a little door that is hinged with silk on one side. The door is perfectly camouflaged in the ground. The spider opens the trapdoor and waits for prey to approach.   

Lately I have come across a number of beetles.  

 

This June Beetle pupa began life as an egg laid in the soil. While in the grub stage, it fed on the roots of grasses and other plants. This stage lasted for three years! It pupated this spring and will soon emerge as an adult but stay underground until the following year. 
 

I found two different species of June Beetles (also known as June Bugs) not far from the pupa. Perhaps they recently emerged and will remain in the soil until 2021. Or are they females preparing to lay eggs? So much to learn! 

Another common encounter is the multi-legged centipede!  
 

Centipedes are often confused with millipedes but are unique in a number of ways. They have 1 pair of legs per segment vs. 2 pairs in millipedes.  Centipedes also have 2 “poison jaws” on their head which they use to paralyze their small prey. The round-bodied, slower-moving millipedes are detrivores and have no need for deadly mouth parts!   

Naturalist Rebecca Dandekar recently found this bark centipede tending her eggs in her garden.   

Clearly soil is not just a bunch of lifeless dirt! It is the matrix for life for thousands upon thousands of species. In fact, scientists estimate a billion organisms can be found in a teaspoon of soil.   

With that in mind, I can’t wait to get back to my garden and see what surprises await!