Volume 45, Number 4,
July 1999: Carpenter Ants

Text-only version

ISSUE HOME PAGE

ABOUT THIS ISSUE
- about KSN
- about the authors

IN THIS ISSUE

Section 1:
- introduction
- what is a carpenter ant?

Section 2:
- life cycle
- colony size

Section 3:
- how carpenter ants find their way around

Section 4:
- feeding habits
- optimizing feeding
- territorial ants go to war
- avoiding war

Section 5:
- why active at night?
- ecological value of carpenter ants

Section 6:
- surviving winter
- destroying wood
- contrast between termites and carpenter ants

- References

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Carpenter Ants
by John H. Klotz, Laurel D. Hansen, Byron L. Reid and Stephen A. Klotz

SURVIVING IN WINTER

What happens to the ants during the cold winter months?  Parent colonies containing the queen, workers, winged reproductives, and larvae overwinter in a metabolic state termed diapause. In temperate regions, diapause is a period of dormancy during which the ants are in a state of "suspended animation."  The encasing wood of the colony’s residence provides the overwintering colony with insulation from cold temperatures.  Carpenter ants also produce glycerol, a compound which acts as an antifreeze preventing destructive ice crystals from forming in their bodies.

In temperate regions, colonies break diapause from January to June (depending upon the latitude, elevation, and habitat), and the queen begins her first egg-laying period of the season, lasting for 7–10 days. The voracious appetites of the developing larvae trigger increased foraging activity.The most intense foraging of the season occurs when the workers are driven by increasing food requirement so the rapidly developing larvae.A second peak of activity occurs in June when the queen again lays eggs for a period of 7–10 days. The foraging activity period in the second peak is shorter and less intense, and the colony enters into diapause in September or October along with the late summer brood, which overwinters as larvae and completes development in February. Colonies are perennial and may exist for more than 20 years.

DESTROYING WOOD

Species of Camponotus that live inforest environments and serve as important ecological components are also recognized as structural or nuisance pests in human habitations (Figure 12).

As is the case with many organisms, human activities have greatly influenced the distribution andabundance of carpenter ants. In the northern United States and the provinces of Canada, carpenter ants cause millions of dollars of damage to structures and to standing trees used for lumber.  For instance, a minimum of 50,000 houses are treated each year by professional exterminators in the stateof Washington for carpenter ants, and many more are treated by homeowners themselves.One example from Washington will illustrate the damage that can be done by Camponotus modoc. When an older home was being remodeled, the inner wallboards were completely removed. Most of the wall studs along a 20-foot wall were tunneled by carpenter ants. The most seriously damaged wood was so extensively tunneled that an 8-foot-long two-by-four weighed less than two pounds.This tunneling also extended into the attic joists so that the owner fell with one leg throughthe ceiling while he was showing the damage. A home near Grand Rapids, Minnesota, had sawdust piles to ten inches in height from carpenter ant excavations in the basement and attic.

All across suburban America, it is a common practice to build houses on forested lots without removing the trees. Unfortunately, nearly all forested lots contain one or more carpenter ant colonies, and the newly constructed house is frequently invaded by satellite colonies even before construction is completed.Thus, homeowners are not dealing with colonies that grow from the progeny of a single queen, but their houses suffer from the damage of 5,000 to 50,000 workers in satellite colonies that move into the structure.  Since these houses and other man-made structures have optimal temperature and moisture conditions for the rearing of brood, they are ideal satellite nesting sites.  

Notwithstanding the potential destructiveness of carpenter ants, their household invasion is sometimes a blessing in disguise, at least from the point of view of the scientist.One of the authors took advantage of a carpenter ant infestation to study ant behavior.The colony, whose nest was outside in a tree, followed a telephone wire into the house, through an electrical switch plate and along the edge of a kitchen counter to a loosely capped jar of honey. In place of the honey, a mixture of sugar in milk and diced mealworms were offered to the foraging ants. After several days of feeding on this rich resource, the ant colony migrated into the house and located its new nest site in some moist wood next to dripping pipe underneath the sink.It was in this makeshift laboratory setting that carpenters ants reveals some of their special adaptations which make them so successful not only in their natural surroundings but in our home environments  as well.

Overallthe benefits from the "premier forest predator" far outweigh the harm caused when humans and the carpenter ant meet on common ground. Future studies will surely uncover further secrets of carpenter ants behavior and biology as well as better management techniques.  Living together with carpenter ants will continue to challenge both scientists and homeowners.

Figure 12. Destruction by carpenter ants in a crawl space of a house located in Spokane, Washington. 

CONTRAST BETWEEN TERMITES AND CARPENTER ANTS

Termites

Straight Antennae

Wings of Equal Size

Thick Waist

Ants

Elbowed Antennae

Wings of Unequal Size

Thin Waist