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Off With Their Heads: Ant-Decapitating Flies, And Other Ways To Deter Fire Ants

 Red imported fire ants arrived in the United States in the 1930s, and currently stretch from Virginia to Texas.
Matt Bertone
Red imported fire ants arrived in the United States in the 1930s, and currently stretch from Virginia to Texas.

The Bee Gees wrote and performed it, but it’s red imported fire ants that have truly mastered the art of “Stayin’ Alive.” Since their arrival in the 1930s, fire ants have spread across the United States, even surviving a failed multi-million dollar poisoning effort by the federal government in the 1970s. They currently stretch from Virginia to Texas with some colonies as far west as California.

The more natural shaded, forest-like vegetation people can propagate around their properties and yards, the less likely they are to have a fire ant problem.
Adrian Smith

In WUNC’s new podcast CREEP, co-hosts Elizabeth Friend and Laura Pellicer discuss fire ants’ drive to stay alive in the United States after accidentally being carted here on cargo ships from South America. The ants can inflict painful and sometimes deadly stings, and damage farming equipment by chewing on electrical insulation.

If fire ants are here to stay, what are the best ways to respond if a colony pops up in your backyard? If you’re about to reach for the first fast-acting pesticide in your closet, don’t. The best way to get rid of a fire ant colony is to kill its queen, who devotes her life to producing more ants.

Fast-acting ant poisons will kill worker ants before they get a chance to take the toxin to their queen, and the ants that do die will soon repopulate. Using slow-acting baits or pesticides to play the long game is a better bet.

Here’s how to prepare yourself if these reddish-brown insects lay claim to your backyard—or, even better, how to prevent them from setting up shop in the first place.

  • Time it Right. Strike between late August and early October, when fire ants are still searching for food and aren’t deep below the ground. You’ll also be giving your slow-acting pesticide time to take effect in the winter months, so you can step outside in the spring without fear of getting stung.
  • The Two Step Method. First, use a fire ant bait—usually a combination of corn grits, soybean oil, and a pesticide—on the colony. Then, treat any colonies that persist with pesticides. It may take anywhere from weeks to months for the baits to take full effect.
  • Boiling Water. Pouring hot water onto a mound can instantly kill fire ants, but only if done correctly. It works best when done in the middle of the day, when the queen will likely be at the top of the mound.
  • Wasabi Water. Although this technique is not as well-studied, PhD student at the University of Georgia Horace Zeng says a mixture of wasabi powder and warm water poured into a colony can stunt its development: “After treating the mounds with wasabi water, the ants seem to dislike the mounds, and they don’t … want to come back.”
  • Embrace the Shade. According to Adrian Smith, head of the Evolutionary Biology and Behavior Research Lab at the North Carolina Museum of Natural Sciences, fire ants aren’t a fan of shaded areas. “The more natural shaded, forest-like vegetation people can propagate around their properties and yards, the less likely they are to have a fire ant problem,” said Smith. Using trees and bushes to create as much natural shade as possible in your yard will likely deter fire ants from moving in.
Sanford D. Porter / USDA ARS
A phorid fly emerges from the head of a decapitated fire ant.

And finally, an option not available for purchase but spotlights one of fire ants’ arch nemeses:

  • Ant-Decapitating Flies. Yes, they’re real. Also called scuttle flies or phorid flies, these winged insects can insert their eggs into a fire ant’s body. When the larva hatches, it grows into the ant’s head and licks it clean, causing it to pop off in about three weeks. While phorid flies generally decrease fire ant populations by less than 3%, the presence of these parasitic predators does make fire ants retreat underground for cover, possibly decreasing colony growth.

While these tips should help you keep backyard fire ant populations at bay, keep in mind that as a species, these ants aren’t going anywhere. Even if you stave them off for a year, they’ll likely repopulate—they are an invasive species, after all. So hunker down, search for slow-acting baits, and plant a tree or two. We’re the reason they’re here, so we may as well manage them to the best of our ability.

Want to learn more about fire ants and other species? CREEP is a new podcast about creatures invading our space, and changing the world around us, presented by WUNC and the North Carolina Museum of Natural Sciences. Listen and subscribe wherever you get your podcasts.

Adithi Ramakrishnan is a science reporting intern at WUNC through the AAAS Mass Media Fellowship.
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