This is an Argentine Ant.
They are not an especially big ant. They’re not very dangerous to humans. I’ve had them on me, and if they bit me I’ve never noticed. They’re more annoying than anything – and they are annoying because they are everywhere!
They are native to Argentina, but they have invaded the West Coast of the United States and have done serious damage to the ecology here.
From the Radiolab article & podcast:
Argentine ants are not good neighbors. When they meet ants from another colony, any other colony, they fight to the death, and tear the other ants to pieces. While other kinds of ants sometimes take slaves or even have sex with ants from different colonies, the Argentine ants don’t fool around. If you’re not part of the colony, you’re dead.
According to evolutionary biologist Neil Tsutsui and ecologist Mark Moffett, the flood plains of northern Argentina offer a clue as to how these ants came to dominate the planet. Because of the frequent flooding, the homeland of Linepithema humile is basically a bootcamp for badass ants. One day, a couple ants from one of these families of Argentine ants made their way onto a boat and landed in New Orleans in the late 1800s. Over the last century, these Argentine ants wreaked havoc across the southern U.S. and a significant chunk of coastal California.
In short, there is really only one big “supercolony” of Argentine ant in California, and they all work together, to destroy any possible competitor.
Argentine ants don’t really make a traditional ant hill. They make a nest in a way that is reminescent of FEMA building a town out of trailers. The entire nest is meant to be temporary and mobile. And it doesn’t matter if the nest breaks up into pieces which are relocated in different places – it is still all one big colony, and if an Argentine ant from another nest wanders into a new nest it is welcomed.
If you disturb an Argentine ant nest, you will see the ant nursery pick up the larva and head for safer territory. The queens of the nest (each nest may have several queens) will also flee – but if they are killed it is possible for the workers to nurse a larva into being a new queen.
Nests can be anywhere. They love to nest under rocks or bricks on the ground, in the space between soil and planters, in potted plants, in porous wood or in many other places. People have reported nests in their vehicles, or in their boats. The ants need a source for food and for water, and the lawn sprinklers give them the water. Lawns (among other things) provide food.
Argentine ants form long supply lines to sources of food. It is common to see a thick line of ants 100 feet long traveling along an interior wall in a home in order to harvest some scrap left out. If you were to kill off this line of ants, the queens in the colony respond by dramatically increasing the amount of eggs that they lay.
In other words, killing some Argentine ants results in the creation of many more replacements.
Another source of food for the Argentine ant is aphids. These ants will “farm” aphids for their honeydew, and the resulting increase in aphids on a plant usually means that the plant is doomed.
My garden and aquaponics setup was attacked by Argentine ants.
In the garden, the ants took over the squash, pumpkins, melons, and corn. They actually nested in the ears of the corn, and farmed aphids on the stalks. All of these plants were producing until the load of aphids and scale insects overcame the plant and swiftly killed it. My pepper plants and pear tomato plants survived.
The Argentine ants actually tried to nest in the biological filter of my aquaponics system. We had to be careful to ensure that the filter was always filled to the brim with water, because any filter material above the water line became a haven for the ants.
Controlling these pests in the garden is not going to be easy. Scale insects are resistant to common control methods, and beneficial insects will have to compete against the Argentine ants. Wendy has identified an ecologically safe way of attacking these insects that we will try to implement.
But for now, our harvest this year is somewhat meager (well, except for the pear tomatoes, which Wendy tells me are extremely excellent).
We have been busy (and successful) in combating parasites in our bluegills, and have been learning more about them. We are creating an indoor breeding station for bluegills, for guppies (to feed the bluegills) and for crayfish. I’ve finally figured out what the final Aquaponics setup will look like, and have started clearing that area. We also have been successful in breeding mosquito fish, duckweed, and water hyacinth. I’m gearing up to work through the cooler winter months to get ready for next season.
I’ll have some photos posted soon.