Carpenter Ants

Family: formidicidae (sf:formicinae)
Species: camponotus spp.
Common Names: carpenter ants
Antennae Characters: elbowed
Hosts: structures
Cultural Control Methods: kitchen hygiene.
Physical Control Methods: vacuum the nest
Pesticides Used: baited pesticides, fumigants
Notes: Among the largest of common ants (.65-1.25cm long) w/ brown or black bodies. No antennal club; as for other non-stinging ants the 1st abdominal seg has a single hump; tip of abdomen has circlet of hairs. Formic acid ejected at anus as defense & may bite. Nests in (but does not eat) wood.

Agriculture and Agri-Food Canada

Insect Identification Sheet No. 92 1983

Carpenter Ants

The red and black carpenter ant, Camponotus herculeanus L., is one of the largest ants in Canada, and is found throughout the country, mainly in the south. Like all ants, it lives in colonies, each consisting of hundreds of workers, several dozen males and one or more queens.

Injury:

Outdoors, carpenter ants nest in old trees, stumps, posts or logs. They often infest the outside woodwork of buildings such as verandahs, wooden steps and sills next to foundations. They damage and weaken wooden structures by tunneling. Although they prefer damp, decaying wood, they somearial tunnel through sound dry timbers in any part of a building. These tunnels are their living quarters and the borings are not eaten but removed as sawdust. The sawdust may not always be evident as it may accumulate within walls, under floors, in attics and in other undisturbed places. Another species, C. noveboracensis (Fitch), nests in soil, and is harmless.

Life History:

As in all ants, the first segment of the abdomen forms a very narrow waist. The workers are 6 to 13 mm long, males 9 to 10 mm and females from 12 to 25 mm. The body is uniformly dark brownish black, with a reddish brown thorax. By comparison, the black carpenter ant, C. pennsylvanicus (DeGeer) is a uniform dark brownish black.

Carpenter ants overwinter as adults. They lay their eggs during warm weather. The egg stage can last 24 days, the larval stage 21 days, and the pupal stage 21 days. The pupa forms inside a thin case. A well established colony can produce winged sexual forms that leave the colony to mate. The mated queens fly to nearby sites where they establish new colonies. The males die soon after mating.

Control:

Remove decaying or infested wood from around buildings. Do not store firewood for long periods. If possible, replace infested wood with sound material.

For further details contact your provincial Department of Agriculture or click here for the Safe and Sensible Pest Control brochure on carpenter ants.

Written under contract to the BC Ministry of Environment, Lands and Parks (now Ministry of Water, Land and Air Protection) by: L. Gilkeson.

Carpenter Ants:

The sight of large, black carpenter ants scurrying across the floor is a worrying sight for homeowners because it might mean that somewhere in the house insects are chewing on wood. Ten species of carpenter ants are native to BC. They are medium to large ants, 6-12 mm long (3/8-1/2 inch); the flying queen ants may be nearly 2 cm long (7/8 inch). Ants can be distinguished from termites by their narrow "wasp-waist" and antennae that have an elbow bend in the middle (termites aren't indented at the waist and their antennae are straight) (Fig. 1).

Carpenter ants are one of the most beneficial predators in the forest ecosystem. They feed on small insects and honeydew and they scavenge dead insects and decaying material. They are particularly prolific in the moderate climate and high humidity of coastal British Columbia. For brief periods in the spring and early summer the winged carpenter ants swarm into the air on mating flights. The queens are easy to see as they settle, shed their wings and search for crevices in decaying wood to begin their nest. Very few of them will find an ideal site (usually outdoors) and their presence does not mean that the house is infested.

Carpenter ants make two types of nests. If the queen finds moist, decaying wood, she tunnels into it to begin the main nest. This site must be permanently moist or the eggs and younger larvae cannot survive. Old nests can contain thousands of ants, but it takes several years for a new nest to build up to a few hundred individuals. Main nests are usually outdoors in rotting stumps, trees or in decaying landscape timbers. They can become established in houses where wood in the structure has begun to decay. Although carpenter ants do not eat wood, they do tunnel into it to make their galleries. Once they establish a nest in damp wood they will eventually damage the structure by tunnelling from the decaying wood into the sound wood. Carpenter ants also make satellite nests where they care for the older larvae and pupae that tolerate drier conditions. These nests are often in wall voids and eaves, ceilings or under insulation in attics or crawl spaces. Most nests in houses are satellite nests that maintain communication with the main nest. The two ways to deal with carpenter ants are:

1. prevent them from entering in the first place, and
2. remove infestations that have become established.

Prevention:

The best protection from damaging infestations is to maintain dry conditions with proper construction and maintenance of the house. There is a risk of carpenter ant infestation anywhere wood is in contact with soil.

1. Repair wood damaged by moisture and ventilate damp areas. Clean gutters to avoid clogging, which leads to water damage to siding or roof.
2. Store firewood on raised platforms, well away from the house.
3. Prune trees so branches don't touch the house.
4. Remove all nearby rotted stumps or logs. Check for rotting landscaping wood.
5. Ensure that wood of the siding or structure isn't in contact with soil at any point around the house foundation.

Control:

The key to controlling ants is finding the main nest, where the queen is laying eggs. This requires thorough inspections and an effort to follow foraging ants back to their nest. If you see more than 10-12 ants in your house in an evening, it is worth investigating whether their nest is in the house or whether they are on a foraging expedition from outdoors. First, make sure the insects in question are carpenter ants. If in doubt, catch some of the largest ones and have them identified. Follow some of the ants until they lead you back to the nest. Somearial carpenter ant are interested in sweet food in the early spring and you may be able to attract some to jam or honey and then follow them homeward. They use the same trails over and over and are most active at night. During the inspection of the house, thoroughly check the crawl spaces and attics as well as under porches. Look for signs of nesting activity, such as mounds of loose shavings or sawdust beneath a crack in a wall or eave space. Also, listen for rustling sounds in the walls (use a rolled up paper tube to amplify the noise). Carpenter ants particularly like to nest in wall cavities, under siding, between floors and where wood is in contact with soil. Satellite nests
can also be near roof gutters, downspouts and in the ceiling.

1. Find and remove the nest material manually or by vacuuming. Vacuum up any stray ants. You will know it is a nest if you see ants carrying white, oval pupae or larvae.
2. If no structural damage has occurred, prevent ants from re-entering the space by caulking the entry cracks.
3. If structural damage has occurred, repair it and remedy any underlying moisture problems.
4. To kill ants travelling through walls or cavities or to prevent them from re-entering a wall use one of the following dusts. They will remain effective for up to 20 years if kept dry. Boric acid, a fine powder with low-toxicity to humans is a stomach poison to insects. It is formulated into domestic pest control products for ants and other household pests. Wear a dust mask, gloves and eye protection while applying boric acid dust. Apply it and store it out of the reach of children and pets because it could be harmful if enough is eaten. Diatomaceous earth (silicon dioxide) is a non-toxic white powder made from ground up shells of diatoms from ancient marine deposits. It kills insects by causing them to dehydrate. Use plain diatomaceous earth or products formulated with pyrethrins, which are fast-acting, short-lived compounds extracted from pyrethrum daisies. Wear a dust mask when applying the dust to avoid respiratory irritation.

How to Treat:

Concentrate on applying a fine layer of dust to house wiring and plumbing pipes, wherever they can be reached. Research has shown that ants use these as pathways through the wall voids. Unscrew
the cover plates from electrical switches and outlets (turn off main power first!) and insert a dust applicator wand alongside the box. Apply a fine layer of dust to the wires on either side of the box. If the house has a sealed vapor barrier around the electrical box, be sure to reseal this with caulk or plastic tape after applying the dust. Apply dust to any accessible plumbing pipes in walls and crawl spaces.

Severe Infestations:

The control measures given above may not eliminate established ant infestations in high risk houses, such as those surrounded by woods, those on earthen crawl spaces or with decaying timbers in the foundation. In this case, or if you are unable to make the necessary inspections, it is advisable to call a licensed professional pest control service to locate the problem. Choose a service that will conduct a thorough inspection for the main nests and that is willing to discuss with you, in detail, the advantages and disadvantages of various treatments. To prevent the problem from recurring after treatment, replace or repair any damaged timbers and correct moisture problems. If you choose to have the pest control service apply pesticides to the perimeter of the house to prevent future carpenter ant invasions, it is important to know that the only areas it is necessary to treat are:

1. along the top of the sill from inside the crawl space, and
2. under the bottom edge of the siding on the exterior.

IPM FOR STRUCTURAL PESTS — ONE COMPANY'S EXPERIENCE
BOB LUCY; PROFESSIONAL ECOLOGICAL SERVICES, VICTORIA, BC

Carpenter Ant Control:

1. Search for attractions. There are many things that can attract carpenter ants to a building, such as warm conditions or water-damaged wood. We identify these attractions and recommend ways to eliminate them. Elimination of these attractions is very important for long term carpenter ant control.
2. Search for nests. Carpenter ants usually have more than one nest site. We spend a lot of time following ants in order to locate their nests. Somearial we must do this work at night when the ants are most active. Unfortunately nests can be in tree roots, in dense woods, on neighbouring properties or inside walls and can be impossible to find.
3. Eliminate nests. When we can find and get at a nest, it is easy to eliminate it. If a nest is inside a wall, we usually recommend that we open the wall to get at the nest. Once accessible, most of the ants in the nest can be vacuumed out and the remaining ants killed with a low toxicity insecticide. If we cannot find a nest, we try to eliminate it by applying appropriate insecticides in the areas the ants walk.
4. Install a barrier. A teflon barrier on the foundation of the building is too slippery for the ants to walk
   across. It prevents the ants from getting into the house to look for food and prevents them from moving in from nearby nests.
5. Spray insecticides. Areas outside the house where the teflon cannot be installed are protected with an insecticidal barrier.
6. Maintain the outside of the house. After the initial control work is done, it is very important that the house be maintained to prevent the ants from reentering so that carpenter ants find it unattractive and difficult to enter the house. At least once each month during the summer the teflon barrier is checked, cleaned, and reapplied where needed, the insecticide barrier is reapplied where needed, and vegetation growing near the house is checked to ensure that it has not grown to make a bridge across the barriers.

Try dusting the entries and exits of the nest in the infested area with "Drione" dust. The material is available thru the many nationwide outlets for "Van Waters and Rogers" chemical distributors. It is 99.5% ground silica and .5% pyrethrum — an organic derivative of the chrysanthemum flower and is one of the safest materials for this application. Any of your local pest control companies should be able to perform the work for you if you choose not to do it yourself.

John Lipka Owner/Operator Silicon Valley Pest Management San
Jose, CA
JCLIPKA@aol.com

From: from NISUS Corporation (a supplier of borates) web site:

"INTERIOR VOID TREATMENTS
The treatment of interior wall voids has become more popular with the availability of borate dusts. The efficacy of these dusts depend on ants ignoring their presence and walking through them, contaminating the ants' bodies in the process. Ants then ingest the borate while grooming.

One limitation of this control method is that the dust must be placed directly onto the pathway used by the ants. If, for example, the dust is placed on the floor plate and the ants are using an electrical conduit located three inches above the plate as their pathway, control will not be attained.

Another problem with using dusts are their sensitivity to high moisture conditions. Dusts have a tendency to cake or crust when they get damp. This makes them ineffective since ants can then walk across them without picking any up on their bodies.

SPOT TREATMENTS OF INFESTED WOOD
Spot treating infested wood with BORA-CARE® will quickly eliminate a localized carpenter ant infestation. Whenever practical, inject BORA CARE directly into the carpenter ant galleries. However, it is important to treat an entire infested area in order to reduce the possibility of colony relocation. A frequent problem encountered with carpenter ants is the fragmentation of a colony subjected to a pesticide. BORA-CARE®, like many other pesticides, is repellent to carpenter ants and may cause them to avoid treated areas and seek out untreated wood. The best treatment method consists of not only treating the infested area, but also treating all wood susceptible to attack. This would include an entire crawl space, wall or attic showing any signs of damage. All bare wood should be sprayed to the point of wetness. Confined areas can be treated using a foaming or fogging device but heavily infested wood should be directly sprayed either before or after fogging."

• see also Safe and Sensible Pest Control for Carpenter Ants
• and Integrated Pest Management Manual for STRUCTURAL PESTS in British Columbia (Chapter 3: Ants)