The purpose of a curse is to inflict misfortune with moral significance—even a sense of justice. Curses, otherwise known as execrations, are as old as dirt—if not older. In Genesis 3:14 God says to the serpent, “Cursed are you above all livestock and all wild animals.” Whether or not you believe this, you must admit nature is full of calamitous events (coincidental or not) that provide support for the idea that curses exist. Disease, predation, starvation, draught and wildfire—take your pick. In the human realm—also part of nature—we can add crime, war, torture . . . and fire ants! I will never forget my mother’s introduction to these loathsome insects. Visiting from out of state, I watched her admire flowers growing in our back yard when she suddenly began hopping and jerking like a crazed marionette. She had stepped in a fire ant nest. Welcome to Texas, mom!
Texas has its own native fire ant but it’s not considered a problem. The nasty ones are invasive, imported fire ants. These pugnacious aliens come in two colors: red and black. In this part of Texas, the red hordes are more common. Both are invasive, both are imported from South America, both have excruciatingly painful bites and both have an attitude. Fire ants are among the most despised and detested pests in Texas. Remedies and insecticides flood the marketplace, but these give only limited relief. What we need is a curse on fire ants!
Turns out, one already exists and it produces ghastly effects—way beyond anything Harry Potter could conjure. The hex manifests as a seemingly harmless fly whose larvae burrow into ants, take control of their minds, eat their brains and eventually sever their heads from inside. “Yes, yes,” I shriek, “to hell with the Society for Fairness or League of Decency, tell me where I can find these little dementors!”
Our miniscule protagonist (phorid fly) is here on a green card from South America to help the USDA Agricultural Service with the war on fire ants. And I thank God they’re on our side!
It all starts with reconnaissance. Phorid flies frequent fire ant mounds, looking for a suitable martyr. They are not really “hunting” the ants per se, but, rather, looking for a place to incubate their eggs. The first step is to hover close to the quarry. Once selected, it’s over in a split second. The fly strikes with a 2-stage hypodermic-type ovipositor, somewhere in the membrane between the ant’s legs. After the initial penetration, a smaller shaft fires a tiny torpedo-shaped egg into the ant. “Houston, the rover has landed.”
This act, in itself, is a small aviation miracle. Robert Plowes, a research scientist from the U.T. Department of Integrative Biology, describes it as “Like a duck trying to lay an egg on the back of a pick-up truck moving down a highway. In other words, it’s tricky.”
When the egg hatches in a few days, the greedy maggot finds its way into the ant’s head where it lives on bodily fluids, continuing to gather strength. Meanwhile, the ant still works as a productive member of its community. As it develops, the parasite needs its host to remain where food is plentiful—it is, after all, eating for two. But alas; even then, the larva is chemically taking control of the behavior of the ant in a bizarre and puzzling act of mind control.
In the beginning, the larva feeds mainly on the ant’s jaw muscles, causing “Zombie-like” dangling jaws. After two weeks, the developing fly is able to manipulate the ant’s motion and develops the ability to control the ant’s movement from the inside. Eventually, there is no brain left in the ant at all and it just starts wandering aimlessly. . . this is when the rest of the colony takes notice. Ant colonies maintain something called social immunity to isolate and exile ants whose behavior is deemed suspicious—for the common good.
Things take an even stranger twist when the larva decides it’s time to kill its host—by now the ant is merely a puppet. Normally, when ants die, they look for hot dry places because that keeps fungi and other pathogens from affecting the colony. But at this point the ant whose body has been invaded is anything but “normal.” For it to develop properly, the pupa needs high humidity. About 24 hours before the maggot is ready to pupate, it “directs” the ant to seek a place deep down in the leaf litter where it remains moist and doesn’t get too hot. The terminal act is a gruesome guillotine-like execution.
Our squatter releases a chemical which destroys the ant’s membranes, including the tissues that hold the head on. What’s left is a severed head (fully encompassing the maggot) and a broken body, twitching in the darkness. The larva then eats away the remaining muscles and glands, completely hollowing out the head. Next, it pushes out the mouth parts to create an exit route and begins to pupate. In the process, the pupa builds a hardened tip, completely filling the mouth opening which protects it as it continues to develop. Then Be-zinga! In a few short weeks a diminutive phorid fly crawls out of the ant’s head in a new body glorified. The horror! The horror! Hollywood couldn’t have scripted the evil birth any better.
Okay, let’s now turn our attention to the adult phorid fly—our “flying guillotine.” As we get to know these little assassins better, it’s important to remember they come from a very large and diverse family tree.
The Phoridae are a family of small, hump-backed flies resembling fruit flies. There is about 4,000 species worldwide; most are found in the tropics. Researchers say that fire ants in their home region are controlled by as many as 23 phorid species. Since they are host specific, other ant species aren’t bothered—only the one tagged by Mother Nature. That’s why, after crossing the border, South American imported fire ants had no natural predators in this country. In 1997, Pseudacteon tricuspis Borgmeier was the first species of Pseudacteon fly successfully tried as a biological control agent for imported fire ants in the U.S. Since then, we have added to our arsenal. Altogether we have recruited 5 distinct species to our cause.
All right class, raise your hand if you’ve ever personally seen a phorid fly! These buggars are tiny—only condemned fire ants and a handful of biologists are likely to see them in action. If you put one on a U.S. penny, its body would stretch from Lincoln’s nose to about the tip of his upper lip. Not all flies are imported . . . we have domestic phorid flies too. Some keep our native fire ant population in check while others are only non-parasitic household pests. In no case do the ant-decapitating species threaten humans or other animals. Unfortunately, that’s not the case with imported fire ants.
Swarms of fire ants can severely injure humans or kill small animals and pets that stumble across their nests. Fire ants cause $1.2 billion per year of economic damage to Texas alone and infest an estimated 80 million acres of rangeland. For reasons not fully understood, they commonly swarm on circuit breakers and other electrical equipment, causing them to malfunction. Overall, these stinging marauders cost the U.S. economy as much as $6-$8 billion annually in agricultural damage, pest control costs and sweet, sweet profits for emergency rooms.
Most researchers say the invading multitudes got their start (probably on an agricultural produce boat) in Mobile, Alabama in the early 1930’s. The hordes moved through Texas in the 1950’s and are still moving north. Another accident, this time in Queensland, Australia, started a similar invasion on that continent (as if they didn’t already have enough trouble!).
So . . . will phorid flies eradicate our imported invasive fire ants? Overall, phorid flies do seem to slow fire ant colony growth but they will probably never eliminate them in the U.S., just as they haven’t in South America. Sadly, invasive fire ants are here to stay. The hope is that over an entire region and over decades, phorid flies can become a more economic and safe way to reduce the pests to a tolerable level. Keeping the population under control is our best hope.
Now I ask you . . . which represents the most contemptable curse, fire ants or phorid flies? Is the mischief created by one right while the other is wrong? It’s true that life is fragile; life hangs by a scrap. And it doles out wins and losses for different players. But curses are a human idea, derived from a concept of good and evil. Nature doesn’t judge; it sees clearly. Nature sees right and wrong as merely the same color in different light.