Monday, March 8, 2010

Carpenter Ants by Ralph H. Maestre, BCE

Carpenter ants are a nuisance by their presence when found in parts of the home such as the kitchen, bathroom, living room and other quarters. When 20 or more large winged and/or wingless ants are found indoors, in the daytime near one location, it is possible that the colony is well established in the home and the nest may have been extended into sound wood, sometimes causing structural damage. They do not eat wood, but often remove quantities of it to expand their nest size. However, if only one to two large wingless ants are erratically crawling, they may simply be foraging for food with the nest located outside. Outdoors, they are frequently seen running over plants and tree trunks or living in moist, partly rotten wood stumps. Nevertheless, carpenter ant inquiries rank first over all other household/structural pests in many states.


Carpenter ants are among the largest ants found in homes and live in colonies containing three castes consisting of winged and wingless queens, winged males and different sized workers. Winged males are much smaller than winged queens. Wingless queens measure 5/8 inch, winged queens 3/4 inch to the tips of their folded brownish wings, small minor workers 1/4 inch and large major workers 1/2 inch. Workers have some brown on them while queens are black. Workers have large heads and a small thorax while adult swarmers have a smaller head and large thorax. Carpenter ants have a smoothly rounded arched (convex) shape to the top of the thorax when viewed from the side and a pedicel between the thorax and abdomen consisting of only one segment or node. They have constricted waists, elbowed antennas and the reproductive's forewings are larger than the hindwings, transparent or brownish and not easily removed. Adults are usually black with some species red, brown or yellow occurring on parts of the body and legs. Eggs are about 1/8-inch long, cream colored and oval. Larvae are legless and grub-like, later pupating in tough silken, tan-colored cocoons erroneously referred to as "ant eggs."

Carpenter ant queen her first brood of eggs and larvae

Life Cycle and Habits
Winged male and female carpenter ants (swarmers) emerge from mature colonies usually from March to July in New York City and Long Island. After mating, males die and newly fertilized females (mated for life), establish a new colony in a small cavity in wood, under bark, etc. and each lays 15 to 20 eggs in 15 days. The egg stage takes about 24 days, larval stage 21 days and pupal stage 21 days or about 66 days from egg to adult at 70 to 90 degrees F. Cool weather may lengthen this period up to 10 months. The colony does not produce swarmers until about three years later. A mature colony, after three to six years, has 2,000 to 4,000 individuals.

In later generations, workers of various sizes are produced (polymorphism) into major and minor workers, which are all sterile females. Males formed are winged swarmers. Larger "major" workers guard the nest, battle intruders, explore and forage for food while smaller "minor" workers expand the nest and care for the young. Workers, when disturbed, carry off the larvae and pupa, which must be fed and tended or they die. In a mature colony, there is usually one queen with 200 to 400 winged individuals produced as swarmers. Workers have strong jaws and readily bite (sharp pinch) when contacted.

Nests are usually established in soft, moist (not wet), decayed wood or occasionally in an existing wood cavity or void area in a structure that is perfectly dry. Workers cut galleries in the wood, expanding the nest size for the enlarging colony. Galleries are irregular, usually excavated with the wood grain (sometimes across the grain) into softer portions of the wood. The walls of the nest are smooth and clean (sandpapered appearance) with shredded sawdust-like wood fragments, like chewed up toothpicks (frass), carried from the nest and deposited outside. Carpenter ants do not eat wood but excavate wood galleries to rear their young ants and carry aphids to plants, placing them on leaves for the production of honey dew. The food diet is of great variety (omnivorous) of both plant and animal origin such as plant juices, fresh fruits, insects (living or dead), meats, syrup, honey, jelly, sugar, grease, fat, honey dew (aphid excrement), etc. They feed readily on termites and usually never co-exist with them in a home. Workers are known to forage for food as far as 100 yards from their nest.

Control Measures
The most important and often most difficult part of carpenter ant control is locating the nest or nests. Once the nest location is found, control is very easy and simple. Sometimes more than one colony is present in the structure or on its grounds, so a thorough inspection is very important. Steps to a successful inspection include an interview with family members, indoor inspections, outdoor inspections and sound detection.

Often children and adults of the residence know where ants are seen, where large numbers are most prevalent, movement patterns, moisture in the structure, moisture problems of the past, if swarmers were seen, location of sawdust-like material in piles, populations outdoors, etc.

Indoors Inspection
Nests can be found in either moist or dry wood. A moisture meter can find wet spots to pinpoint possible nest locations. Inspect behind bathroom tiles, around tubs, showers, sinks, dishwashers, washing machines, refrigerator drip pans, etc. Check wood affected by moisture from contact with the soil such as steps, porch supports, siding, seepage from plugged drain gutters, chimney flashing, wooden shingle roofs, hollow porch posts, columns, leaking window and door frames, window boxes, crawl spaces, pipes, poor pitch of porch roofs, flat deck porch roofs, under porches, attics, etc. Look for damaged timbers, swarmers in spider webs, wood piles indoors, piles of wood debris ejected from the colony (pencil sharpener shaving-like), "windows" or small opening to a nest, etc.

Notice NO Mud in the galleries

Inspection Outdoors
Look for ants traveling from a tree or stump to the structure. They may travel over tree branches or vines touching the roof, electrical and telephone wires, fences next to the house, piles of firewood, logs, or railroad ties nearby or hollow living trees with entrance knot holes, etc. Workers are most active at night (midnight), traveling from their nest to a food source following trails but no particular trail leading directly to the nest. They do establish chemical (pheromone) trails.

Sound Detection
An active colony may produce a distinct, dry rustling sound (sometimes loud), similar to the crinkling of cellophane. It may be heard in a wall when standing in a room. A listening device, such as a stethoscope, may be useful when conditions are quiet and outside noises are at a minimum.

Homeowners should trim all trees and bushes so branches do not touch or come in contact with the house. Correct moisture problems such as leaking roofs, leaking chimney flashing, or plumbing, poorly ventilated attics or crawl spaces and blocked gutters. Replace rotted or water-damaged wood and eliminate wood to soil contact. Remove dead stumps within 50 feet of the house, if practical, and repair trees with damage at broken limbs, and holes in the trunk. Seal cracks and crevices in the foundation, especially where utility pipes and wiring occur from outside is paramount. Be sure to store firewood off the ground away from the house and bring in only enough firewood (first examining it) to be used quickly.

If the nest is located in a wall void, it is best to dust directly with Tri-Die, Drione, or Boric acid. Drilling 1/4 or 3/8 inch holes into the wall, sills or joists, where the nest is located, will best help the insecticide penetrate. Treat three to six feet on either side of where ants are entering to hopefully contact the nest. Some drill a series of holes at 12-inch intervals in infested timbers to intercept cavities and galleries of the nest. Holes can later be sealed by putting in dowels as plugs, small corks or covering with an appropriate sealant and touched up with paint, leaving no visible damage from the repairs. Spraying or dusting the baseboards or cracks and crevices around the infested area with residual insecticides, without locating and treating the nest, usually does not give complete control. Kill might be slow with only crack and crevice treatment since workers need to carry enough insecticide on their feet back into the nest. Ants in the nest can live more than six months without feeding. However, aerosol spray treatments in the nest can be effective if much insulation is present. Approaches and areas adjacent to the nest must be thoroughly treated with residual insecticides such as Phantom or other approved product. Outside the structure, all breaks where ants can enter the home must be treated, and a perimeter spray applied against the foundation wall at least two feet up and three feet out. Be sure to treat under the lower edge of sidings, around window and doorframes and the chimney flashing.

There are many insecticides labeled for ant control. Before using an insecticide, always read the label, follow directions and safety precautions. For professional assistance, contact Magic Exterminating to eliminate your carpenter ant problems.

Most apply a perimeter spray treatment around the house foundation. Avoid simply spraying each month whenever ants are seen. Infestations will continue unless nests are eliminated. Locating the nest is not always easy, but is essential for control.

Keys words: Carpenter Ant ID, Colony Size, Polymorphism, Frass, Omnivorous, Foraging Distance, Nest Sites, Proper Inspections, Pest Proofing

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