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Ants

Ants are often considered pests in Maine schools because they are unwelcome visitors inside buildings. Since most ants do not pose a serious threat to human health or property a common sense approach to managing them should be taken. Indoor infestations are best treated or better yet, prevented, by practicing good sanitation and maintenance to keep ants from wandering indoors in search of food and water.

It is usually not advisable or effective to apply pesticides to floors or baseboards indoors or as a perimeter treatment outdoors.

pavement ant, Tetramorium caespitum (Hymenoptera: Formicidae) - 5393404

Identification

Pavement ants may be the most common indoor pest in Maine. They are an invasive species, originating in Europe and now widely spread across the United States.

Worker pavement ants are uniformly small, about 3mm long. They are dark brown to black in color with a shiny gaster. There are striations on the head and dorsal surface of their thorax and their 12-segmented antennae end in a 3-segmented club. Foraging ants are usually active on the floor and along the edge of the walls near door frames. During warmer days a number of winged male and female ants may swarm inside and they are usually trapped near a window as they try to escape towards the sun.

They become pests when nesting in a building to be closer to a food source, and sometimes by building nest openings between bricks of patios or other sensitive areas.

 

Biology

Pavement ants in nature occur primarily in open meadows under rocks and other debris. In more urban settings, pavement ants nest under sidewalks, under building foundations and under patios, usually near cracks through which they can enter the building. There is normally a single queen although larger colonies may have additional queens. The workers live for several years and the largest colonies can exceed 10,000 workers.

Indoors, pavement ants will nest under floors, within walls and inside insulation. They prefer to nest near heat sources during winter and are often seen in the walls of ground-level masonry. Pavement ants also follow pipes, which they use to access upper floors of homes and buildings.

Pavement ants are not a threat to the structure of buildings and homes. Pavement ants can be annoying but don’t bite or spread diseases.


Pavement ants can be tracked by the trails of workers foraging for food. They prey on subterranean termites, insects in the soil, plant juices, and a wide assortment of foods containing sugar and protein. This includes fruit, syrup, grease, seeds, dead insects- they will consume essentially anything that falls to the floor. Worker ants forage predominately at night but during early spring and summer but will also forage during the day. They communicate a food source to one another by laying a chemical trail from the food source back to the nest and it is common to see a trail of ants inside a building.

 

Inspecting for Pavement Ants

Start inspections at the ground floor or sub-floor level because the pavement ant often originates outdoors at ground level. Follow trails of ants to locate colony/colonies. Outside, trails are usually hidden by grass or mulch next to the building foundation or the edges of pavement. Inside, you can often find trails under edges of carpets along the tack strip. Pavement ants utilize electrical wires, conduit, and water pipes as highways throughout the building. Performing an inspection at night around 10 or 11 PM can be useful since pavement ants are most active at night. Outside, piles of soil near slabs and concrete are a good indication of underground galleries.

 

Preventative measures include:

  • Cleanliness- it is important for areas to be very clean to prevent ants- this includes corners, cupboards, shelves, and baseboards.
  • Sweep and mop floors away from baseboards. This prevents food particles from being imbedded in the board and attracting ants.
  • Clean up food and drink spills promptly
  • Keep pet and human food in pest-proof containers
  • Empty trash frequently
  • Rinse and store recyclable cans and bottles in pest-proof containers
  • Trim shrubs, trees and grass touching building
  • Clean gutters
  • Repair leaks and condensation problems promptly
  • Caulk cracks and keep screens, weather-stripping, door sweeps in good repair.

 

 

Carpenter ants

Carpenter ants cause considerable damage to buildings and should be eliminated when found in buildings. They are usually black and tend to be somewhat large (up to 1/2" long). Carpenter ants are often encountered in trees, stumps, and rotting logs outdoors but will come into schools buildings in search of food, water and nesting sites.

  • Inspect trees and stumps near buildings at night for carpenter ant activity.
  • Infested stumps and trees located near building should be removed.
  • When nests do occur in buildings they are usually in association with moisture problems such as roof or plumbing leaks. Inspect attics, window sills and frames, porches, around sinks and dishwashers, foundations sills, to detect and repair leaks or condensation problems. Small piles of wood particles and/or dead ants found near any of these areas are an indication of carpenter ant nesting activity.
  • The key to eliminating carpenter ants is to locate and remove (or treat) the nest. This is usually a job for a professional exterminator.

Outdoors. All ants can bite when disturbed therefore, ant nests sometimes present a hazard to children on playgrounds. This is especially true for the European red ant, a species found in a few isolated coastal locations in Maine, including Mount Desert Island and Cape Elizabeth. These ants cause a very painful bite thereby presenting a special concern if found on school grounds. Seek assistance from a pest control professional for treatment of European red ant nests.

For other ant nests found on school grounds where children are at risk from bites, the following method can be used.

  • Mix a solution of soapy water (3-4 tablespoons of liquid dish soap/gallon water) in 5-gallon plastic buckets.
  • Standing a foot away from the nest (wear long pants or coveralls and tuck pant legs into socks to avoid ant bites), slowly pour soapy water into the nest. Have a partner poke holes in the nest with a stick and continue pouring water in. Continue using the stick to open the mound and pour more soapy water until no more live ants are seen.
  • Excavate the nest with a shovel and pour more soapy water into depression.

 

Chemical Control


If nonchemical methods alone are ineffective, or only partially effective, then integrating a pesticide into your management program may be warranted. Anyone making pesticide applications on school property must be licensed by the Board of Pesticides Control. See "Standards for Pesticide Applications and Public Notifications in Schools". This includes bait traps and sprays.


Spraying for ants in or around the perimeter of a school is not suggested. This is usually very ineffective.

Anyone making pesticide applications on school property must be
licensed by the Board of Pesticides Control. See "Standards for
Pesticide Applications and Public Notifications in Schools".


Printable Version [PDF]

 

Additional Resources:

Eurasian Red Ants (University of Maine)
Pavement Ants (Penn State PDF)
Pavement Ants (Harvard University PDF)
Ant Management for Schools (Minnesota School IPM PDF)

 

Photo credits:

Joseph Berger, Bugwood.org