The pavement ant, (Tetramorium Caespitum), is a common household pest. Its name comes from the fact that colonies usually make their homes in pavement. It is distinguished by one pair of spines on the back, two nodes on the petiole, and grooves on the head and thorax . The species is native to Europe, but was introduced to North America in the 18th century.
The pavement ant is representative of a broad group of ground nesting ants that are found throughout the southern and eastern parts of the Canada. Pavement ants live in colonies with a social structure. Homes and buildings with slab-on-ground type construction are particularly prone in invasion by pavement ants.
Pavement ants vary in color from red brown to blackish-brown in appearance and are from 2 to 3 mm length. They have four stages of their life cycle: egg, larva, pupa, and adult. Six to eight weeks are required for development. The time varies because of the season of the year, and the temperature. Colonies have three distinct castes: queens, kings, and workers. The only function of the queen and king is to reproduce. All of the workers are sterile females. The workers build the nest, take care of the young, and hunt for and gather food. The workers are the ones that you find invading a home looking for resources.
They will eat almost any kind of food. Sweets, starches, greases, meats, fruits, and vegetables are all acceptable as food. Pavement ants needmoisture and will travel some distance to find a source.
Pavement ants usually nest outdoors in the ground under sidewalks, driveways, in the cracks of pavement, in lawns, and near the foundation of buildings. Occasionally they will nest in walls, under floors, and in insulation. They enter a home or building through any natural opening or even the smallest crack in the slab or the foundation wall.
Pavements ants need warmth, moisture, and a food supply for their colony to continue to grow and develop. The workers are sent out like "little trucks" to forage and gather these basic needs. Once they have gained entry into your home they will search for food and moisture. This is especially true during the winter months when cold weather limits their outside activity. When they appear on cold winter days they have probably exhausted their stored food supply in the nest and they are out looking for additional food or moisture. They will appear inside homes and buildings during the summer when the conditions outside are extreme. This might occur after very heavy rain when the ground is saturated or just the opposite, during periods of drought when the ground is dry and they need moisture.
The winged ants or "swarmers" are the kings and queens. Researchers are not certain of the exact cause for the pavement ants to swarm out but it appears to be related to the size of the nest, the age of the nest, and perhaps the weather conditions. Most swarming occurs between May and July. Once they emerge and complete their mating, the newly fertilized queens look for a suitable spot to start a new colony. Fortunately, most of them are unsuccessful and die off.
The use of baits is currently the most effective methods of control.
Baits are very effective and efficient in eliminating a pavement ant infestation provided the ants will accept the bait. Ant baits contain a slow acting poison and are formulated as gels, solids, and liquids. The worker ants gather the bait and carry it back to the nest where they feed the immature stage (larva). The larvae process the bait and then through a process known as trophalaxis they regurgitate a liquid to feed the queen and the other workers. The workers get their "reward" so they will continue to go out and bring back more food and do the other work required by the colony. This process spreads the slow acting poison throughout the nest and causes the entire colony to die off. This is a very successful method provided the ants take the bait.
Baits will be placed in areas inaccessible to young children and pets. Look for pavement ants moving about, especially the trailing activity. We place small amounts of bait directly in the path the ants are traveling, but we do not cover or block their entrance to the colony with the material. They are likely to gather around the bait or immediately pick it up and transport it back to the colony. It is not unusual for many pavement ants to suddenly appear after the bait is placed. This is normal foraging activity so please do not disturb the ants or apply any insecticides to kill them. Let them feed on the bait. Over the next three five days the feeding sites will be very busy. Within a week the pavement ants should be gone.
Liquids may be applied directly to ant mounds found in the lawn and to ant mounds found along foundations and in cracks of sidewalks, patios, and pavement.
Outdoors, if necessary we treat up under the siding where it meets the foundation, the ground directly against the foundation along the perimeter of the house, and the expansion joint between the foundation and the driveway, sidewalk, or patio. It may take 4-6 liters to thoroughly treat the exterior of a typical three or four bedroom home.
When we are treating outdoors please be sure to move toys, pet feeding bowls, grills, patio furniture, etc. away from the foundation before making a treatment.