• UD Search

Ants in the House

Below is a table describing ant varieties in Delaware that you may wind up seeing in or around your home at some point. The table will help you identify and learn about control methods for removing them from your property.

Species What size & color are they? How do you tell them from other ants? Where are they found in the house? What do they eat? How should you inspect? What can the homeowner do? What should the professional do?
CARPENTER ANT Worker ants are 1/8 - 1/2 inch; black. Winged reproductives are larger -- almost 1 inch. Large size. 1-node ant. Microscopic circle of hairs at tip of abdomen. Profile of thorax evenly rounded. Can be confused with Allegheny Mound Ant. The main Carpenter Ant colony is not in the house -- it is in a tree in the yard. Satellite colonies nest in moist wood in the house, but do not eat wood. May be seen in kitchen foraging for food. Travel through wall voids. Insect honeydew, plants, fruit juices, insects and other arthropods. They will also eat: sweets, eggs, meat, cakes, and grease. Look for small piles of debris on floors. Check gutters for potential moisture problems. Check trees in yard for main colony. Listen for chewing sounds in walls. Homeowner should correct the moisture problem in house. Seal cracks and crevices to stop entry into house. Trim back tree branches that touch house. Homeowner pesticides may eliminate the occasional forager in the living quarters of the house, but may not eliminate the colony which will continue to tunnel in moisture-damaged wood. Find trails from house to main colony in yard. Use pesticide and baits to create barrier between main colony & house. May need to inject pesticide into wall voids. Leave the main colony alone -- that is part of nature.
PHARAOH ANT 1/16 inch. Light yellow/ tan in color. Abdomen may be darker. 2-node ant. Antenna 12 segmented with 3-segmented club. Easily confused with Thief Ant which has a 10-segmented antenna and 2-segmented club. Pharaoh Ants nest in inaccessible warm, humid places near food/ water sources. They use utility lines to move about the house. Pharaoh Ants have a range of food: syrup, fruit, meat, dead insects. They need carbs for maintaining the colony. They also need protein for reproduction and development of the young. The colony may shift food preferences as their needs change. Look for small light-colored ants in the kitchen and around pet dishes. NEVER use an insecticide spray. Pharaoh Ant colonies have several hundreds of reproductive females. Insecticide spray causes the main colony to bud into 2, then 4, then 8, then 16……….. The professional must use a bait for control of Pharaoh Ants. Pre-baiting with non-toxic bait to locate the ants is recommended. The professional needs to know whether the colony is looking for carbs or protein and switch baits as the colony food needs change.
THIEF ANT 1/16 inch. Light yellow/ tan in color. 2-node ant. Antenna 10 segmented with 2-segmented club. Easily confused with Pharaoh Ant which has a 12-segmented antenna and 3-segmented club. This ant gets its name from the habit of nesting near other ant colonies and stealing their food! Thief Ants prefer high protein foods: meat, bread, fruit, animal fats, oil, nuts and dairy. They will also feed on sweets. Look for small light-colored ants in the kitchen and around pet dishes. Don't use an insecticide spray. You may have Pharaoh Ants! Keep pantry foods in tightly sealed containers. Don't leave food sitting out in kitchen. Control grease while preparing & cooking food. After ensuring that you do not have Pharaoh Ant, the professional needs to find the nest by following workers back home. Wall voids may need to be dusted with insecticides. Barrier treatments may be recommended. Baits may be effective.
ODOROUS HOUSE ANT 1/16 - 1/8 inch. Brown to black in color. This ant is the most common ant in Delaware homes and the most difficult to control. 1- node ant. The node is hidden beneath the abdomen. When crushed, this ant gives off a "rotten-coconut" like odor. These ants usually construct their nests in wall voids around hot water pipes and heaters, in crevices around sinks and cupboards. Odorous House Ants prefer sweets, but will also eat high-protein foods and grease. In other words, they eat anything! Look for tiny dark ants in the kitchen. They often come out of electrical sockets and forage on the kitchen counter. There is little a homeowner can do. Sanitation will not stop the ants. Homeowner pesticides may eliminate the occasional forager in the living quarters of the house, but will not eliminate the colony. The professional will apply a barrier insecticide treatment and baits. Often two applications about 2 weeks apart are required for control. The homeowner must be patient and wait 2 weeks after the last application before asking for additional applications.
CRAZY ANT 1/16 - 1/8 inch. Dark brown to black. 1-node ant. Antenna and legs very long. These ants usually construct their nests underneath floors and in wall voids especially near hot-water pipes and heaters. While Crazy Ants prefer to eat other insects and sweets, they will feed on almost any household food. Look for small dark ants in the kitchen that seem to run haphazardly about in search of food. There is little a homeowner can do. Sanitation will not stop the ants. Homeowner pesticides may eliminate the occasional forager in the living quarters of the house, but will not eliminate the colony. The professional can apply a barrier insecticide treatment and baits.
LITTLE BLACK ANT 1/16 inch. Dark brown to black. 2-node ant. No spines on thorax. Antenna 12-segmented with 3-segmented club. These ants will nest in decaying wood and masonry. Little Black Ants feed on grease, oil, meats, fruits, vegetable materials, and sweets. Look for small black ants in the kitchen. There is little a homeowner can do. Sanitation will not stop the ants. Homeowner pesticides may eliminate the occasional forager in the living quarters of the house, but will not eliminate the colony. The professional can apply a barrier insecticide treatment and baits.
ACROBAT ANT 1/16 - 1/8 inch; light brown to black 2-node ant. Hold abdomen over thorax & head. Pedicel attached to upper surface of abdomen. Abdomen heart shaped when viewed from top. Nest in moist wood. Follow utility lines & wires. Acrobat Ants enjoy honeydew from aphids on ornamental plants. They also eat dead insects, sweets, & high-protein foods such as meat. When found indoors, look first at the structure's exterior. Look for trailing ants on the foundation & utility lines. Inside look for piles of debris, especially Styrofoam insulation. Homeowner should correct the moisture problem in house. Seal cracks and crevices to stop entry into house. Trim back tree branches that touch house. Treat ornamental plants to eliminate aphids. The professional may inject pesticide into the wall void, spot treat at point of entry and use baits.
PAVEMENT ANT 1/8 inch. Dark Brown. 2-node ant. 12-segmented antenna with 3-segmented club. One pair of spines on thorax. Head and thorax have visible grooves. These ants nest beside and under sidewalks, driveways and building foundations. During the winter, the ants often nest inside the home in the vicinity of a heat source. Pavement ants will eat a wide variety of foods, such as dead insects, grease, seeds and sweets. Honeydew produced by homopterous insects is a favored food. Look for these ants around trash containers and on kitchen counters. Homeowners can eliminate Pavement Ant colonies in the driveway and near the house foundation. Kitchen sanitation will help reduce the infestation, but not eliminate it. The professional may inject pesticide into the wall void and under floors, spot treat at point of entry and use baits.
FIRE ANT 1/16 - 1/4 inch. Body yellowish red and abdomen black. While Delaware is not within the Fire Ant range, we have had isolated cases of Fire Ant infestations. 2-node ant. No spines on thorax. Antenna 10-segmented with 2-segmented club. When the Fire Ant mound is disturbed, the mound will "boil over." These ants almost always nest outdoors, but have been known to nest behind baseboards in the home. Fire Ants feed on any plant and animal material. If you see an ant mound in your yard and it "boils over" when disturbed, call your County Extension Agent. At this time, Fire Ant control in Delaware must be left to the Delaware Department of Agriculture. At this time, Fire Ant control in Delaware must be left to the Delaware Department of Agriculture.


Original Publication Date:

Cooperative Extension Education in Agriculture and Home Economics, University of Delaware, Delaware State University and the United States Department of Agriculture cooperating. Distributed in furtherance of Acts of Congress of May 8 and June 30, 1914. It is the policy of the Delaware Cooperative Extension System that no person shall be subjected to discrimination on the grounds of race, color, sex, disability, age, or national origin.

Disclaimer: Reference to commercial products or trade names does not imply endorsement by University of Delaware Cooperative Extension or bias against those not mentioned.

Print This Post Print This Post