Solenopsis molesta

School of Ants collection
Literature record

Solenopsis molesta

From Dr. Eleanor's Book of Common Ants

A.K.A.: Thief ants

Size: 0.06 in

Where it lives: Thief ants nest underground in forests and open, grassy areas. They also like to nest in human structures. They particularly like nesting near other ant species’ nests.

What it eats: Tiny ants with big appetites, thief ants prefer protein like dead insects.

What’s the big deal?

Back in the days of the Wild West, Jesse James and his outlaw gang were some pretty crafty dudes. They robbed everything from stagecoaches and trains to banks and homes. His bandit bunch crept into towns, only to high-tail it out ahead of angry lawmen and Wanted posters bearing James clan faces. Imagine if the Jesse James family moved in right next door to your house! Many ant species across the United States face this predicament every day when thief ants (a.k.a. Solenopsis molesta) come to town. Thief ants are the Jesse James gang of the ant world, and these bite sized burglars pickpocket and plunder anything they can get their little mandibles around, living lives of artifice that would make Mr. James sit up and take some notes.

Even though he was a robber and a murderer, Jesse James won the public’s hearts, in part because he was easy on the eyes. Thief ants are no different. Whenever I stumble upon a thief ant nest or happen to lift a dead insect and find a bevy of thief ants, mid-snack, I always stifle a squeal. Thief ants are unbelievably, ridiculously cute.

Their size might play a big factor in their cute-ness. At 1/16th of an inch, a thief ant worker could wander comfortably around in the lower case “o’s” on this page. Most often a golden yellow color, thief ant workers vary along the color spectrum all the way to amber. They have stingers but are too tiny to cause you any pain. They look like they wander around really slowly, but actually they’re just super small. If you had a microscope, you could see that each antenna has a bulb on its end, and they bonk about as they feel their way to and from food. Much of that food, remember, is stolen, either from other ants or from you and me.

Thief ants get their name from their habit of setting up camp next to other ant species’ nests. Thief ants love protein and stuff their bellies on dead insects, people food, and insect eggs (Zenger and Gibb 2001). When the other ants bring home thief ants’ favorite foods, those crafty little burglars sneak that food right on over to their own houses and feast. They’ve also been known to smuggle out other ants’ babies, tasty snacks for greedy thief ants. When other species’ colonies are weak or dying, thief ants aren’t as sneaky. They run through the nests’ halls like children running down the aisles of a Toys R Us shopping spree, eating their fill of dead and dying ants.

Their crimes and misdemeanors don’t stop with the insect world: a thief ant will rob you blind if you don’t watch out. Thief ants are opportunists, and they recognize that your kitchen is a wonderful opportunity for the biggest heist of their lives. Because they are so small, many people have a hard time figuring out how to keep them out of their pantries. The best way to keep thief ants out is to figure out how they’re getting in. Once you do that, block their entranceway by plugging holes with some caulk or weather stripping and tell those thief ants there’s a new sheriff in town.

Some people think Jesse James was like a modern-day Robin Hood and that many of his crimes were to benefit others. I don’t know what Jesse did with all of his loot, but many of the thief ants’ crimes against other insects surely do help us out a lot. For example, when they’re not stealing from other ants, they love to eat lawn pests like cutworms and scarab beetle eggs, and they provide effective control against these lawn and golf course pests (Royer and 2004, Lopez and Potter 2003, Zenger and Gibb 2001).

Even though they’re miniscule, they’re pretty good at bullying one of our biggest ant bullies: the Red Imported Fire Ant. Like the James gang, they rely on their cunning and strength in numbers to beat up and eat any upstart fire ant colony making camp in their territory (Rau and Vinson 2004). In fact, fire ants can’t establish nests in areas where thief ants roam (Vinson and Rau 2004).

Being tiny has its advantages. Because thief ants nest underground and out of sight, they are one of the few ant species who can weather the havoc wreaked by other nasty invaders like Argentine ants and yellow crazy ants. When other ant species get kicked out of town, thief ants hold their ground (Wetterer et al. 2001, Wetterer 1999).

Jesse James’s shoot-‘em-ups and looting sprees came to an abrupt end when he met the wrong end of Robert Ford’s pistol. Fortunately, thief ants survive even the toughest ant assassins. They beat up fire ants and outwit Argentine and yellow crazy ants. Unlike Jesse, who caused trouble with the law wherever he went, thief ants contribute to our natural world. They help keep other pieces of nature in check by eating dead insects and aerating the soil with their underground nests. You could even say they are lawmen in their own right, nibbling away at the pests crawling around your lawn. They’re tiny but tough, and they’re outside your door right now. Despite their name, thief ants live mostly on the good side of the law.

Find out more about this species at Antweb and see more photos at Alex Wild's photography site.