12 Types of ANTS found in California!
There are dozens of ant species that live in California!
Trying to list them all would be impossible. 🙂
Below are the most common and abundant types of ants, which are part of the insect family Formicidae.
12 ANT SPECIES in California:
#1. American Winter Ant
- Prenolepis imparis
- Adults range from light to dark brown, often with a darker abdomen.
- When viewed from the side, they have an hourglass or peanut shape.
- The abdomen of worker ants is often large and swollen from reserves when foraging.
The American Winter Ant earned its name for its unique ability to move about and forage in temperatures that send other ants into their nests for shelter. When other ants are foraging in the summer, they usually seal themselves into their nests and enter a hibernation-like state.
They may seem insignificant, but these insects are essential to our forests. Many native wildflowers like bloodroot, trillium, and violets depend on this ant for survival. The plants have a calorie-dense appendage attached to each seed, encouraging the ants to harvest and transport them to a new location.
American Winter Ants can also withstand invasive ant species in California!
This is partially because of their ability to forage at cool temperatures and their defensive capabilities. They are aggressive with other ants and produce abdominal secretions that are lethal to many other ant species, including the invasive Argentine ant (Linepithema humile).
#2. Immigrant Pavement Ant
- Tetramorium immigrans
- Workers are dark brown to blackish.
- They have longitudinal, parallel ridges on their head and thorax.
Immigrant Pavement Ants thrive in urban areas of California. These European natives like building underground nests in areas with little vegetation. Consequently, you’ll often see them nesting near sidewalks, patios, foundations, and pavement.
Each of about 1000 ants defends a territory of around 460 square feet (43 m2). It’s common to see colonies battling for territory boundaries, especially in spring, as new colonies are established. The workers also forage for honeydew excreted by aphids, seeds, insects, fruit, and human food like bread and cheese.
Gardeners may be happy to see immigrant pavement ants around their property since they are significant predators of coddling moth larvae, a major agricultural pest in North America.
#3. Odorous House Ant
- Tapinoma sessile
- Adult workers are usually a uniform color ranging from brown to black.
- They have a distinct rotten odor when crushed.
Odorous house ants are incredibly widespread because they can adapt to nearly any habitat in North America. They tolerate various habitats from sea level to 13,000 feet (4000 m) of elevation and occupy urban areas, forests, grasslands, bogs, and sandy coastal areas.
These ants are also commonly seen in homes in California.
And they aren’t just searching for a comfortable place to live; odorous house ants love sweets! In the wild, they tend to feed on aphid honeydew and flower nectar, but they will gladly take advantage of human food when available.
They often nest outside on stumps, rocks, matted grass, and other debris but use cracks and termite-damaged wood found in homes. Interestingly, these nests aren’t stationary.
Odorous house ants tend to move their nests about every 21 days. They also tend to coexist peacefully with other ant species rather than strictly defend a territory.
#4. Dark Rover Ant
- Brachymyrmex patagonicus
- Adult workers are very small and uniformly brown.
- Their antennae have nine segments.
- They have relatively large eyes and long hairs on their backs.
Native to South America, the dark rover ant made its way north in the 1970s. Dark rover ants are often considered a nuisance species because they build nests in gardens or homes. In urban areas, it’s common for them to use mulch and manufactured structures to build nests. In hot, dry climates, these ants tend to be drawn to the moisture in kitchens and bathrooms. Thankfully, they don’t bite, sting, or carry any diseases.
These ants have spread into California because they sometimes form “supercolonies.”
Rather than have a single nest with one queen, occasionally, a colony will form multiple nests, sometimes with hundreds of reproductive queens.
Additionally, dark rover ants peaceably coexist with other native and introduced species, including those usually intolerant of other ants. They also help control another invasive species, the cactus moth (Cactoblastis cactorum).
#5. Longhorn Crazy Ant
- Paratrechina longicornis
- The workers are grayish-black or brownish-black.
- They have pale brown legs and long, 12-segmented antennae.
- They have numerous coarse hairs on their body and a small circle of hair on the tip of their abdomen.
This may be the most widespread ant species in California and even the world!
Longhorn crazy ants are originally native to the tropics but easily adapt and make themselves at home in disturbed areas, urban areas, and inside buildings.
They are called crazy ants because of their erratic movement patterns. Rather than traveling in straight lines like many ant species, these ants rush around with seemingly no pattern or direction.
Part of their success in spreading worldwide may be due to their varied omnivorous diet. Longhorn crazy ants will feed on seeds, plant sap, fruit, dead insects, honeydew secretions from aphids and other insects, and human household scraps and waste.
Thankfully, these ants don’t pose any threat to humans. However, they can bite enemies to defend the colony and bend their abdomens to aim and shoot formic acid at them.
#6. Argentine Ant
- Linepithema humile
- Workers are reddish-brown, occasionally darkening to black at the tips of their abdomens.
- They have a single node or petiole between their body and abdomen and heads that are longer than wide.
- Workers are small and relatively hairless.
According to the Global Invasive Species Database, Argentine ants are among the world’s 100 worst invasive animals. Native to South America, these ants are now found on every continent except Antarctica!
A crucial reason for their success is their ability to create what scientists call “megacolonies.” Unlike many other ant species, Argentine ants aren’t aggressive or competitive with other ants of the same species. Instead, they form extensive networks of interrelated colonies, and each colony has multiple queens. Studies have shown that these super colonies may extend for hundreds of miles! Their cooperation means they spend less time and resources defending nests and more time foraging.
While Argentine ants aren’t aggressive and don’t directly harm humans like fire ants, they have some significant negative impacts. These ants farm pests like aphids, mealybugs, and scale insects and eat the larvae of many essential pollinators. Both these factors decrease crop yields.
#7. Rough Harvester Ant
- Pogonomyrmex rugosus
- Workers vary from dark red to brown or black but are uniformly darker than other harvester ants.
- They have many lines and punctures on their heads and bodies, giving them a rough texture.
- Their antennae have twelve segments.
Also known as the desert harvester ant, this ant mainly inhabits dry landscapes in California. You can find them in grasslands, deserts, and scrublands.
Rough harvester ants form large, crater-like mounds at the entrance to their nest.
Their colonies grow large and may include up to 15,000 workers. These workers use the same trails when leaving the nest, creating noticeable, permanent pathways.
Like other harvester ant species, they primarily feed on grains and seeds. However, unlike other harvester ants, rough harvesters usually aren’t agricultural pests. This is partly due to their habitat, which isn’t ideal for growing crops.
#8. Black Harvester Ant
- Veromessor pergandei
- Workers are shiny, dark brown, or black.
- Their heads are as wide as they are long and have large, conspicuous mandibles.
- They have short white or yellow hairs on their heads, bodies, and legs.
Black harvester ants thrive in the hottest, most arid regions in California.
One of the easiest ways to find them is to look for their huge chaff piles. These chaff piles are made from husks and extra material from processing grains and seeds, which are the ants’ primary food source.
Harvester ants are often viewed negatively. However, they do have some incredible benefits. Their chaff piles and “trash dumps” frequently provide homes for other insects like beetles that scavenge them.
Additionally, the outer rings of their nest areas are also some of the most fertile land in their harsh habitat. The extra nutrients and decreased competition that result from the ants’ activity give vegetation in this area an advantage. For example, after a wildfire, the nest rim vegetation is often the first to recover and helps recolonize the rest of the area.
Black harvester ants also don’t tend to be major crop pests. They feed primarily on wild plants like perennial shrubs, creosote bush (Larrea tridentata), and burro weed (Ambrosia dumosa).
#9. Western Black Carpenter Ant
- Camponotus modoc
- Workers are dull black with dark red legs.
- Workers may be up to 0.5 inches long (13 mm).
- They have golden hairs that are most abundant on their abdomens.
Western black carpenter ants are usually found in forested areas in California.
They seem especially fond of coniferous forests but will also use aspen and hardwood forests.
They’re called carpenter ants because they usually make their nests in dead wood, such as stumps and rotting logs, especially those with some bark attached.
Unfortunately for humans, this predisposition to wood means they may damage homes in forested areas, especially log or wood homes. They can be especially troublesome because they form massive colonies, sometimes containing 50,000 workers. That many ants can certainly cause damage to a cabin or house!
#10. Western Thatching Ant
- Formica obscuripes
- Most workers typically have reddish-orange heads, reddish-orange or black chests, and black abdomens.
- Small workers may be all black or dark brown.
- They have one node between their upper body and abdomen.
These are the only ants in California that build thatched roofs for themselves!
Western thatching ants create huge dirt mounds, but rather than leaving them bare like many species, they cover them with a layer of twigs, grasses, and other small pieces of plant material. Precisely what they use depends on their location.
These thatched roofs allow them to survive a wide variety of temperature, humidity, and weather conditions. The size of the colony’s mound generally depends on its age. Those of mature colonies regularly reach 18 inches (45 cm) tall, but even taller mounds aren’t uncommon!
Take a closer look at this astonishing species in the video below.
#11. Southern Fire Ant
- Solenopsis xyloni
- Workers typically have a red head and upper body and a black abdomen, but occasionally, they may be uniformly dark brown.
- Workers may be up to 0.25 inches long (6 mm).
Historically, southern fire ants were the most common fire ant species in California.
However, the spread of red imported fire ants (Solenopsis invicta) has significantly reduced their populations. This is unfortunate for humans as the red imported fire ant has a much more painful sting.
Southern fire ants build smaller, inconspicuous mounds that you may not notice. However, don’t mistake these for harmless ant nests. Southern fire ant workers will swarm out of the nest to defend the colony if disturbed.
They grab their attackers by biting them before delivering a painful sting. There’s a lot of them, too. Mature colonies can contain thousands of workers.
#12. Western Velvety Tree Ant
- Liometopum occidentale
- Their heads and thoraces are reddish-brown, and they have velvety black abdomens.
- Workers may be up to 0.25 inches long (6 mm).
These ants prefer to nest under bark or in the crevices of trees in California.
They prefer oaks, alders, elms, and creosote bushes. Like carpenter ants, their preference for wood nests can make them an issue for homeowners. They prefer moist conditions and are often found near windows and in bathrooms.
It can be hard to eliminate this species because western velvety tree ants are adaptable. They regularly prey on other insects and carefully tend and farm honey-dew-producing insects. Additionally, they will eat sugary foods that humans have left out. It’s common to spot massive lines of these foraging ants extending almost 200 feet (60 meters) from their nest sites.
Did you like learning about the ants that live in California?
Check out these ID guides focusing specifically on different insects and arachnids in California.
- MOST Common Insects
- Butterflies
- Wasps & Hornets
- Dragonflies
- Bees
- Ladybugs
- Moths
- Stink Bugs
- Cockroaches
- Caterpillars
- Spiders
- Millipedes & Centipedes
- Scorpions
- Ticks
- Grasshoppers
Do you need additional help identifying ants in California?
If so, check out this excellent ID guide!
Which of these ants have you seen in California?
Leave a comment below!
