How a fungus can turn soldier beetles into zombies
Soldier beetles are commonly spotted in the late summer and early autumn. This probably is because they are often found on colorful late bloomers such as goldenrod and Queen Anne's lace.
But zombies, you ask? Indeed. We'll start with the beetles and work our way down the Halloween trail to zombies.
Beetle basics
Members of the beetle family usually have hard forewings that protect the membranous hind wings and a soft abdomen.
In other words, unlike wasps, beetles favor thick defense over toxic offense. I tend to think of these hardened wings like medieval armor.
The thicker the wings, the more protection they offer. Japanese or ladybird beetles are good examples.
That said, not all beetles have these hardened wings. Lightning bugs are actually soft-bodied beetles as are soldier beetles.
These half-inch oblong beetles are red, yellow, or orange with a pair of black spots on their wings.
Back in the day, this combination of bright color with black trimming reminded folks of military uniforms hence the name soldier beetle.
Their soft bodies earned soldier beetles another name, leatherwings. ("Leatherneck" marines, anyone?)
Assembling the troops
There are a wide variety of soldier beetles. We'll concentrate on a common local species, the goldenrod soldier beetle (Chauliognatha pennsylvanicus). The wings are yellowish to tan.
The underside of the beetles are black with yellow markings.
Its yellow and black wardrobe suggest the warning colors of bees and wasps.
This is appropriate since our beetle soldiers are armed with defensive chemicals that make them less desirable targets for predators.
When spotted on coneflower and other blossoms in July through September, the soldier beetles are eating pollen and nectar plus an aphid or two along the way.
Not surprisingly, these active fliers are useful pollinators. They seem especially attracted to yellow flowers.
The rest of the year
Before the beetles show up in the dog days, where have they been? If they're not feeding, when you spot them, it is not uncommon to find pairs of mating soldier beetles. This is because they lay their eggs at the end of summer.
The eggs are laid in clusters in the soil. They will hatch in autumn and live as larvae through the winter.
The larvae look like dark, slender fuzzy worms with a mouth for chomping down the enemy, I mean, prey.
In particular, soldier beetle larvae eat grasshopper eggs, little caterpillars, and other soft-bodied critters.
Early in the summer, the larvae transform into pupae, eventually to appear as adult soldier beetles later in the season.
Night of the Insect Dead
Whether it was George Romero's 1968 film "Night of the Living Dead" or Michael Jackson's 1983 video "Thriller," zombies have had a prominent place in pop culture.
Stories of reanimated dead bodies span cultures, continents, and time. But did you know that there are six-legged zombies as well as two-legged ones?
And that these ethereal entomological entities might be haunting a field near you?
The discovery of reanimated dead insects was made by Alfred Russell Wallace in 1859 while he was exploring tropical forests.
Wallace was a British naturalist, geographer, and a contemporary of Charles Darwin. Both men proposed that natural selection powered evolution.
Back to the zombies, Wallace found the enlivened ant corpses were infected with a pathogenic fungus now known as, not surprisingly, zombie-ant fungus.
Turns out similar pathogenic fungi (plural of fungus) can be found in ants, flies, cicadas and soldier beetles here in North America.
Zombie fungus assault maneuvers
Fungi are largely a kingdom of microscopic organisms that can be found virtually everywhere. Humans use fungi, such as yeast, to make bread, beer, and antibiotics.
In the natural world, fungi are essential for breaking down dead organic matter and returning nutrients to the soil.
Instead of seeds, fungi use tiny spores to reproduce. As you might expect, many of these spores thrive on dead organisms.
Rather than wait for a creature to die, zombie-ant fungus help speed things along.
Sooner or later, an active soldier beetle crawling on an aster or goldenrod will pick up an incredibly minute fungus spore.
Soon thereafter, the spore germinates and penetrates the exoskeleton of the doomed beetle.
The fungus rapidly multiplies and takes control of the soldier beetle's nervous and muscular systems.
This soldier is now a virtual zombie. It no longer has a life of its own. It's taking orders from the fungus.
The first order is to march to the leaves near the top of the plant. This behavior is known as summiting.
Once there, the beetle fungus-puppet clamps it jaws on a leaf and dies. Now the zombie fungus gets dead serious.
Hours later, the fungus triggers the undead beetle to snap open its wings and extend its abdomen.
As you might recall, soldier beetles are often in search of a mate. This provocative pose essentially says, "Come hither."
Unbeknown to the live male beetle, its zombie mate is spewing forth a profusion of spores from its elevated perch.
The dead beetle's body has become a zombie spore factory. These spores are likely to infect the mating male and any other nearby soldier beetles. Talk about gruesome chemical warfare!
You'll be happy to know that unlike human zombies, soldier beetle zombies can't move.
Are they in Illinois? I'm not sure. However, they have been spotted from Arkansas to North Carolina.
I think it's just a matter time … particularly for the soldier beetles.
Once a population of soldier beetles is infected, the fungus kills about 20% of the soldiers every year.
Halloween is coming
Since I promised a walk down a scary trail, I'll end with a spooky poem.
I can't help but think that the zombie-ant fungi would agree with the sentiment of this verse.
"Undead need life" by Rani
lacking a heartbeat
pale eyes and discolored skin
body all rotting
hungry for humans
wise brains, a delicacy
undead too need life
• Mark Spreyer is the executive director of the Stillman Nature Center. Email stillmangho@gmail.com