Ants are most easily identified using a dead whole ant specimen and a magnifying lens. Relatively few ant species are common household pests, while identifying ant species found outdoors requires more detailed identification guidelines, which are specific to the area you live in.
Step
Part 1 of 5: Preparing the Ants for Identification
Step 1. Take time to observe his behavior
Although identification is not always necessary, ant behavior varies from species to species. Write down where you found the ants, and what they eat or collect if any. Note whether the ants are the same size and shape, or if some are significantly larger than the others.
You can observe the way they carry their food, how fast they walk, the gait they make, or even the posture they make when disturbed. Most of these details won't be covered in this guide, but they can be helpful if you later narrow down your identification to a few species and need to point out something a little beyond research
Step 2. Collect ants using tweezers or alcohol wipes
Use tweezers or a more suitable tool, but the tip of a cloth or brush moistened with alcohol or ethanol will work as well.
Step 3. Kill the ants by freezing or using alcohol
You can place the ants in a plastic bag, seal tightly, and freeze for 24 hours. Alternatively, place the ants in a small jar with a small amount of alcohol, and check again after a few minutes.
Step 4. Take a hand lens or microscope
Identifying a specific ant species requires careful examination of the very small parts of its body. Lenses with 10x or 15x magnification are strong enough, but you can use a microscope at low magnification if you have one.
Tweezers will be useful again in this study, to adjust the position of the ants
Part 2 of 5: Checking the Ants
Step 1. Make sure the insect you catch is an ant
This may sound stupid, but some termites and wasps are often mistaken for ants. Make sure the ant specimen has the following basic characteristics:
- Ants have "angled" antennae, with well-defined joints, and a narrow waist. Termites have straight antennae and do not have a defined waist.
- There are ants that have a stinger, and there are wasps that do not. Both types of insects have narrow waists, but ants have small "nodes" between their two body segments, while in wasps the segments are directly connected.
- Winged ants have four wings, with the two forelegs being larger than the two hind wings. If all four wings are the same size, you are more likely to get termites.
Step 2. Identify the three body segments
The body of an ant consists of a head, chest the middle, and stomach back. The large back belly is called gaster. Write down or remember the color of the stomach.
Step 3. Look for the node section
Ants have one or two smaller body parts between the chest and stomach, called nodes or petiole. They vary in shape from small spurs, relatively large square lumps, to flattened segments that can only be seen when you separate the chest and stomach with tweezers. This is the most distinguishing part of the ant, and is therefore the most useful in identification. Note the following:
- How many nodes are there (one or two)
- Node shape (sharp edge, round bump, square/lump, or flat)
Step 4. Examine the chest carefully for the spine
Some species of ants, but not all, have multiple vertebrae on the upper side of the thorax (large segment at the back of the head). They are often small and difficult to distinguish from hair, so look for them carefully, and blow gently or wipe with tweezers. Many species have no backbone, while those with backbones usually have one to four near the back of the thorax.
Count the number of vertebrae, if any
Step 5. Measure the length of the ant
Place the ant next to the ruler and note its size. If possible, use a ruler with a millimeter scale, or a 1/32 inch.
Part 3 of 5: Narrowing the Search
Step 1. Find a list of ant names in your area, if possible
There are thousands of ant species worldwide, but typically only a few of them can be found in a single region of the world. Save time by figuring out which ants might be in your area or province, instead of reading through all the explanations.
For some tropical countries and islands you can see interactive guides here, but not all of them are in usable condition
Step 2. Use a wider guide if needed
If we use the worldwide ant species guide, we may have to examine dozens or hundreds of species. If you can't find a local listing, or if none of the ant species described in it fits your specimen description, here are some good choices:
- Visit AntWeb.org. Select Regions in small text near the top of the web page, then select your region from the drop-down menu. Select "Nearctic" for Canada, the United States, and Baja California. Select "Neotropical" for the rest of Mexico and Latin America.
- Alternatively, enter information about your specimen into Discover Life's database.
Step 3. Referring to your ant specimen, read the description at the bottom
The species descriptions below provide additional information that may be useful. Head color, antenna shape (thin or "club-like"), and other information can be obtained easily.
Start by navigating the ant section with one or two nodes, depending on the specimen you have. In each section, the most widely distributed ant species will be listed in detail first. Pests and other species that are relatively easy to find, but with a more limited range of distribution, will be given a shorter description below
Part 4 of 5: Identifying Single Node Ants
Step 1. Identify the Argentinian ant
Found almost worldwide, Argentinian ants are pale brown in color and about (3 mm) long, with pointed nodes. They move quickly in tight rows, prefer sugar but eat protein and fat as well, and have a musty odor when crushed.
Usually colonizes in damp areas outdoors, but is also found indoors. Extermination is very difficult because they have cooperation between colonies and in each colony there are several queens
Step 2. Distinguish the wood ant (Carpenter ant)
These ants are black, dark brown, dark red, or a combination of these colors. They vary in size from " to " (6 to 12 mm), and have one straight node and no backbone. They move in free lines and are often found near forests, along with strong odors and piles of sawdust, dirt, and insect body parts.
Look for the trail around lawns where vegetation has been trimmed or cleared
Step 3. Distinguish the crazy ant
The mad ant is so named because of the speed with which it changes direction, and perhaps because of its odd appearance, as well as its extra long antennae and legs. Its slender body, dark gray, black, or brown in length 1/16 until 1/8 (2–3.5 mm), have flat nodes that are difficult to see, and have no spine.
In the tropics, some species of crazy ants are yellowish-brown and can be up to 1/5" (5 mm), with a darker gastric color (back of the stomach).
Step 4. Identify other species
This single-node species is a common pest in some areas, but has a more limited global distribution than the above species:
- Ghost ant (ghost ant): Very small (1/16" or 2 mm), with a black/brown head and pale belly. Nodes are flat and hidden, no spine. Usually found outdoors in the tropics, or on plants in greenhouses or tropical areas.
- Odorous house ant: 1/8" (3.5 mm) long, nodes flat and hidden, no spine. Gives off a strong and unusual odor when crushed. Mainly found wandering in search of sugar, but varies.
- Rover ant: male worker 1/16" (2 mm), small black color with unusually straight antennae. Most easily distinguished from the much larger, winged female, which is found near light or floating in stagnant water.
- White-footed ant: Ants 1/8" (3.5 mm) long are generally black with pale "legs". Nodes are flat and hidden, have no spine.
Part 5 of 5: Identifying Two Node Ants
Step 1. Identify the acrobat ant
Mixed brown, red, or black in color, about 1/8 (3.5 mm) or greater in length. When disturbed, these ants emit an odor and lift the stinger at the tip of their abdomen. The nodes are slightly raised but not very raised.
The nest is easiest to find by following the trail, and looking for dead ants near holes in the walls
Step 2. Identify the big-headed ant
This ant can be easily identified by its large head among the largest worker ants (1/8" or 3.5 mm in body length), accompanied by smaller worker ants of more normal proportions (1/16" or 2 mm). Two large, round nodes, and two small backbones make it even easier to identify.
These ants prefer to go here and there looking for food from protein
Step 3. Diagnose red imported fire ants
Fire ants are very aggressive, quickly attacking intruders with their painful sting. It ranges in length from 1/16" to 1/4" (2–7 mm), with two raised nodes, and has a stomach that is dark brown in color compared to the rest of the body.
- Often nests in electrical and air conditioning boxes, if installed indoors. Outdoors, they are seen in large numbers after rains, rebuilding their nests in the form of mounds of earth.
- California residents can get assistance in dealing with this species.
Step 4. Identify other species
The following two-node species are pests that are common in some areas, but are not as widespread as the above species:
- Little black ants: Tiny black ants (1/16" or 2 mm), as you might imagine. They have no spine and have a stinger so small that they are barely visible that they are difficult to identify. When nesting indoors, they are found in rotting wood and stone walls.
- Pavement ants usually nest in soil or pavement cracks with small "holes" in the ground. Slow motion, by making grooves in the ground, which can be seen under a magnifying lens.
- Pharaoh ant (Pharaoh ant). Yellow or orange ants that will happily nest almost anywhere, with slightly thicker three-segmented "batons" at the ends of the antennae. Unprofessional attempts to get rid of these ants can make the problem worse.
- Thief ant (Thief ant). Very small (1/16" or 2 mm, or smaller) yellow or brown in color, with two-segmented antennae stick ends. They run in fixed grooves, and can be found hanging around the outlets of electrical appliances or in small holes in food packaged.
Tips
- Ants found outdoors or in the yard may be more difficult to identify, as most identification guides (including this one) focus on species of household pest ants.
- Once you can identify your ant, if it is a pest, find a treatment method that is appropriate for the species. If you can't find a suitable treatment from online sources, ask a professional pest control agency, or a company or store that sells various types of pesticides.
- If you still can't identify your ant, and you don't want to hire a professional, try asking the community at reddit/r/whatsthisbug.
