- The carpenter ant is the most common pest encountered in homes throughout Canada and northern United States.
- There are more than 1,000 species of carpenter ants in the genus Camponotus.
- They get their name from the fact that they possess great carpenter skills that allow them to cut, groove, tunnel, and sand through decaying wood in order to build a series of galleries and tunnels in which they live. They round and smooth their wooden homes to perfection, leaving almost no mess or chippings behind.
- A carpenter ant colony cannot survive without a stable source of moisture: outside, they may seek shelter in dead limbs of trees, stumps, and moist landscape timbers, while indoors, their colony is likely to be set up in a poorly ventilated, overly wet environment, such as attics and crawlspaces.
- They are often mistaken for termites due to their preference for tunneling in decaying wood, but unlike these, they don’t eat the wood as well. There are also plenty of differences in appearance, diet, and behavior between the two.
Carpenter ants are among the biggest ants in Canada. There are numerous species of carpenter ants that may be encountered infesting homes, schools, hospitals, and commercial buildings, but the most common types are the black and red carpenter ants. The red carpenter ant is of a dark brownish-black color on its lower body and reddish-brown on its upper body, while the black ant’s body is dark brownish-black all over. They are typically large insects, measuring from 6 to 25 mm (up to 1 inch) long.
Typically, workers are wingless and can measure between 1/4 and 1/2 inch in length; they are usually the ones venturing inside a house looking for food. Winged reproductive forms (including queens) don’t differ too much from workers in color and shape, but their length can exceed 1 inch. The carpenter ants’ body has a very slim waist and is constricted between the abdomen and thorax; the antennae are elbowed (bent and in sections). The front wing of a swarmer is longer than the other one. Male and female adults will grow wings during mating time.
Diet, Behavior & Habits
Inside the house, carpenter ants feed on protein, sugar, meats, pet food, sugary drinks, grease, jelly, and other sweets. Outdoors, they will look for decaying trees, shrubs, plants, and leaves. While they do bite on wood to create galleries and tunnels for their nests, they do not eat it. When left without their food source, the queen and some workers may resort to cannibalism.
During the warm season, most of their foraging is carried out between sunset and midnight. It is not unusual for workers to travel up to 100 yards from their nest in order to find food sources. It is during their quest for food that they may accidentally find themselves inside a house, usually through the following access points:
- Clogged drains
- Holes in foundations
- Firewood brought inside
- Vines, plants, and tree branches touching the house
- Telephone cables
- Window casings and door frames
- Heating ducts and air conditioners
- Fencing next to home
- Wooden structures attached to the house, such as porches
Because it needs to be permanently moist, the main colony is usually located outside, containing the queen, workers, and immatures. Inside the buildings, ants are likely to build satellite nests in walls, doors, and other hollow spaces that permit the setup, or on the exterior surfaces of the house, such as porches and decks. These are usually comprised of workers, pupae, and mature larvae and don’t need as much moisture as the main nests since they don’t hold too many eggs.
Signs of Infestation
Homeowners are more likely to signal an infestation once they encounter carpenter ant workers and winged ants inside the house. The workers are looking for food and they can be seen forming a trail in areas where food is stored (kitchen, pantry, etc.), while the swarmers are on the lookout for a new nesting site, so they are a sign that the current colony has matured and is ready to establish new colonies. Another sign is the sawdust-like material and other debris they produce from tunneling into the wood, excavated outside by workers; wood shavings and chippings may indicate the presence of a nest nearby. Ant colonies can also be detected by the rustling sound they produce as they chew or move around the nest (the sound may resemble that of rustling cellophane).
Management & Control
Finding carpenters ants inside your home doesn’t necessarily mean that their colony is located inside. Workers may venture inside the house to forage for food and then take it to an outside colony, while queens may find their way inside to look for a good place to set up their nest. Carpenter ants are more likely seek shelter inside your home during part of the year and then move outdoors at other times. Once you make sure you are dealing with a carpenter ant infestation, your next steps should be locating their nest and figuring out the extent of the infestation.
Common nest sites inside the house
- Under attic insulation
- Roofs and attics
- Inside hollow-core doors and door frames
- Sill plates
- Inside moisture-damaged eaves
- Wall voids
- Moist wood around chimneys and skylights
- Under insulation in crawlspaces
- Inside wood porch supports
- Between insulation and subfloors
Common nest sites outside the house
- Roots of dead trees
- Dead limbs of living trees
- Hollow or decaying trees
- Under exterior siding
- Piles of wood
The best control method for carpenter ant infestations is to locate and destroy the nest, while correcting moisture problems and removing food sources. However, removing an ant nest is a challenging task, best performed by licensed pest control professionals who have the knowledge and resources to eliminate the problem at its source. Several methods are likely to be used:
Dust and spray insecticides
. For nests hidden behind walls or inside hollow doors and attics, it is required that a pest control professional drill holes inside those surfaces and apply an insecticidal dust. If the nest is exposed, homeowners can use aerosol insecticides containing bifenthrin, cypermethrin, or permethrin to spray as much of the nest as possible.
. This method should be used in case the nests cannot be located, by combining a food source with a delayed toxicant. Because workers ingesting the toxic bait will continue to live for days and sometimes weeks, they will share the bait with the rest of the colony, enabling the spreading of the bait through trophallaxis
(an ant regurgitates the contents of its stomach to feed another ant).
. This is a solution that can be applied for outdoor nests that cannot be destroyed through physical control methods. The product should be sprayed in a band surrounding the foundation and right under the lower edge of the siding. Insecticides and any other toxic substances should only be applied and managed by licensed professionals, so make sure to resort to a reputable company whenever facing exterior ant problems.
There are certain ways you can consider for preventing future carpenter ant problems indoors:
- The most effective approach is to eliminate the moisture source they depend on for feeding and reproduction. Start by mitigating high-moisture conditions in particular areas of your house. Also, remove moisture-damaged wood structures and wood piled in a garage or near the house.
- If you use firewood during winter, store it as far away from the house as possible. Also, remove stumps, dead roots, logs, and decaying tree limbs within 100 yards of your house.
- Remove branches and vines that come into contact with the exterior of your house or with telephone and electrical lines – carpenter ants are likely to travel from branches to the wiring and find their way inside the house.
- Never allow parts of your house to remain moist for prolonged periods – try to mend roofs, flashing, downspouts, and gutters when they need repairs.
- Keep exterior wood surfaces properly painted and sealed.
- Replace decaying or moisture-damaged wood with sound materials.
- Place moisture barriers in places where ants are likely to be seen: crawlspaces, under wooden porches and decks, and make sure these areas are properly ventilated.
- Seal food in containers and implement good sanitary practices to discourage future ants from venturing inside.
In most of the cases, it is preferable for a specialized pest control professional to treat carpenter ant infestations. Aside from their knowledge and expertise in carrying out thorough inspections of properties, locating nests, and baiting the traps properly, they have experience in using toxic substances to kill the ants and not endanger the lives of other inhabitants. They also have access to specialized equipment and substances that will guarantee the complete removal and prevention of carpenter ant infestations.
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