Imported fire ants are not currently established in New Jersey according to USDA APHIS, so reddish ants or a mound in the yard should not automatically be identified as fire ants. The signs that matter most are mound structure, ants of different sizes within the same colony, aggressive defensive behavior, burning stings, and repeated activity around a specific nesting or entry point.
Signs of Fire Ants
Fire ant identification depends on several characteristics appearing together. A mound, reddish coloration, or a sting can each have other explanations, so focus on the full pattern.
1. A Raised Soil Mound Without an Obvious Central Opening
Imported fire ants build nests in soil and can create raised mounds of disturbed earth. These mounds do not necessarily have a visible opening in the center.
According to USDA APHIS information on imported fire ants, established colonies can produce mounds up to 18 to 24 inches high. Not every colony reaches that size, and workers may reach the surface through underground passages rather than one obvious entrance.
A newly formed mound in New Jersey deserves closer attention when unfamiliar reddish-brown ants are also present, particularly if soil, sod, or nursery plants were recently brought onto the property.
2. A Fast, Defensive Response Around the Nest
Imported fire ants react quickly when their nest is disturbed. USDA reports that hundreds of ants can swarm from a disturbed colony and climb vertical surfaces to sting.
Do not deliberately test a suspected mound by kicking, raking, digging into, or poking it. If activity becomes visible after an accidental disturbance, move away and note whether many ants appear rapidly from the same area.
3. Reddish-Brown Ants That Vary in Size
Imported fire ant workers range from about 1/8 to 1/4 inch long and may appear reddish-brown to black, according to USDA APHIS.
Workers within the same colony can vary noticeably in size. That variation can support an identification when it appears with other fire ant characteristics, but it should not be used by itself. Small ants are difficult to identify accurately based only on size or color.
4. Burning Stings That May Form Pustules
Fire ants bite to hold onto the skin and then sting. The CDC's guidance on fire ant stings describes a burning sensation after the sting, with red bumps that may later develop into small, white, fluid-filled pustules.
The skin reaction alone does not identify the insect. Other ants and stinging insects can also cause redness, pain, swelling, or itching. The combination of repeated burning stings and a nearby active ant colony is more informative.
Seek immediate medical attention for severe reactions such as difficulty breathing or substantial swelling.
BHB's discussion of stinging insects and the problems their stings can cause provides additional context for distinguishing an ant problem from other stinging pests.
5. Repeated Activity at the Same Foundation or Utility Opening
Ants repeatedly emerging from one crack, slab joint, pipe penetration, or utility opening are more useful diagnostically than a few workers appearing in unrelated rooms.
The repeated route may lead to a nearby outdoor nest or a protected nesting area associated with the structure. Either way, tracing the ants back toward their source gives an inspection more useful information than simply treating the workers that are visible indoors.
Are Fire Ants Established in New Jersey?
The red imported fire ant, Solenopsis invicta, is an invasive species introduced into the United States from South America. USDA APHIS currently lists imported fire ant infestations in Alabama, Arkansas, California, Florida, Georgia, Louisiana, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, Virginia, and Puerto Rico. New Jersey is not included.
For a New Jersey homeowner, this means an unfamiliar reddish ant should be identified before it is called a fire ant.
Fire Ants Can Be Moved Outside Their Established Range
USDA regulates several materials that can carry imported fire ants out of quarantined areas, including soil, nursery stock, hay, and soil-moving equipment.
If unusual ant activity begins after sod, soil, or nursery plants arrive, make note of that timing. It does not prove that fire ants were introduced, but it can be relevant when the ants are identified.
What Do Fire Ants Look Like?
Imported fire ants are small and can be difficult to distinguish from other ants without a close look. Their appearance becomes more useful when combined with nest and behavior clues.
Size and Color
USDA describes imported fire ant workers as approximately 1/8 to 1/4 inch long and reddish-brown or black. Workers from the same colony can fall across that size range rather than appearing completely uniform.
Color is less useful than many homeowners expect. Reddish or brown ants are not automatically fire ants.
Why a Red Ant May Be Something Else
Several ant species can be found around pavement, foundations, soil, and buildings. Location alone does not settle the identification.
For example, pavement ants regularly nest around concrete and structural edges. BHB's information on pavement ants and their nesting habits is useful when the activity is concentrated around sidewalks, cracks, or paved areas.
The stronger identification comes from combining appearance with mound structure, worker-size variation, behavior, and the location of the colony.
What Fire Ant Activity Can Look Like Inside a House
Imported fire ants normally nest outdoors in soil, but they can enter buildings while foraging. Less commonly, a colony can occupy a protected structural space.
NC State Extension's red imported fire ant guidance notes that fire ants can sometimes nest inside walls or partly beneath concrete slab floors. Soil or debris appearing around an interior expansion joint, carpeting edge, water pipe, or utility penetration can indicate activity in a wall or subfloor void.
Pay Attention to the Point of Emergence
Repeated activity from one place is more informative than isolated ants in different rooms. Watch for ants emerging consistently from:
- Slab or foundation cracks
- Plumbing penetrations
- Utility openings
- Expansion joints
- Flooring edges near walls
- One recurring structural gap
NC State notes that in most indoor situations, fire ants are entering from an outdoor nest rather than maintaining a colony inside the building.
That is why killing workers on a floor or countertop may not resolve the source.
Fire Ants or Another New Jersey Ant?
Because New Jersey is outside the current USDA established range for imported fire ants, identification should come before treatment.
Useful clues include:
- Worker size and color
- Variation in worker size
- Whether a soil mound is present
- Where the nest appears to be located
- How ants respond when the area is accidentally disturbed
- Whether workers repeatedly use one route into the structure
- Whether soil, sod, or nursery material was recently brought onto the property
No single item on that list confirms the species. Together, they give a pest professional or extension specialist a much better basis for identification.
Why Species Identification Changes the Treatment
Ant species differ in where they nest and how they forage. Ants living beneath pavement, inside structural voids, or outdoors in soil do not necessarily require the same treatment approach.
Finding the nest and identifying the ant are therefore more useful than repeatedly treating workers that happen to be visible.
Why Fire Ant Identification Matters in New Jersey
A suspected fire ant colony in New Jersey deserves careful identification because the state is outside the current USDA established infestation area.
USDA uses quarantines to limit human-assisted movement of imported fire ants from infested areas. Soil, nursery plants, hay, and soil-moving equipment are among the materials that can carry ants to new locations.
For a homeowner, the practical step is straightforward: do not assume that a reddish ant is a fire ant, but do not deliberately disturb an unusual colony either. Document what you can safely observe and have the ants identified.
What to Do if You Think You Found Fire Ants
If several signs match imported fire ant activity, avoid disturbing the suspected colony while you gather information.
1. Keep Away From the Mound
Do not kick, rake, probe, or dig into the nest. Keep children and pets away from the immediate area.
2. Photograph the Activity From a Safe Distance
Photos of the ants, mound, and surrounding area may help with identification. If possible, document where workers are entering or leaving without approaching the nest closely.
3. Note Any Recent Landscaping
Record whether new sod, soil, or nursery plants were recently delivered. Those materials can be relevant because imported fire ants can be transported from infested areas.
4. Trace Indoor Ants Toward Their Entry Point
If ants are appearing indoors, watch for the location they repeatedly use. A consistent crack, pipe opening, joint, or foundation gap can help narrow down where the colony may be.
5. Identify the Species Before Treating the Colony
Fire ants are not the only ants that nest outdoors or enter buildings. Correct identification helps determine whether the colony is outdoors, associated with a structural void, or a different species entirely.
Get Suspicious Ant Activity Identified at the Source
A reddish ant, soil mound, or indoor trail is not enough to confirm fire ants in New Jersey. The state's location outside the current USDA established range makes species identification especially important.
BHB Pest Elimination serves Northern New Jersey and provides ant control services for persistent ant activity around homes and properties. An inspection can help identify the ant, locate the nesting area, and determine how workers are reaching the structure.
If you are seeing unfamiliar ants, repeated activity around the foundation, or a nest you do not want to approach, contact BHB Pest Elimination to schedule an inspection before choosing a treatment.