Volume 41, Number 1, January 1995:
Collection and Maintenance of Ants
and
Studying Ants: A Beginning
by Mark B. DuBois

Text-only version

ISSUE HOME PAGE

ABOUT THIS ISSUE
- about KSN
- about the author

IN THIS ISSUE
- introduction
- collection
- maintenance, observation ant farm
- maintenance, classroom use
- project observations
- literature cited
- books for children on ants

Studying Ants: A Beginning
by Mark B. DuBois
- males, queens and worker ants
- establishing a colony
- caring for young
- growth of an ant colony
- ant senses
- gardening ants
- harvester ants
- parasitic ants
- acrobat ants
- army ants
- questions, activities and investigations with ants
- further reading

SLIDESHOW
View all images in this issue.

Collection and Maintenance of Ants to Use for Teaching
by Roger D. Akre, Laurel D. Hansen, and Elizabeth A. Myhre

and

Studying Ants: A Beginning
by Mark B. DuBois

PARASITIC ANTS

Parasitic ant species depend upon another ant species during part of their life cycle. They exhibit parasitic behavior in different ways. Some queens invade another colony, kill the queen, and depend upon "host" workers to care for their offspring. Eventually, all "host" workers die and leave a pure colony of the temporary parasite ants. In Kansas, Formica subintegra represents this lifestyle. Species such as Polyergus breviceps take this step to an extreme and raid other "host" colonies to replenish the supply of workers as original workers die. Species such as Monomorium talbotae dispense with their own worker caste entirely and depend on the "hosts" for food, defense, and rearing of offspring. It is presumed that "host" queens are not killed by these invaders.

Figure 5. Formica subintegra, head, alitrunk, and petiole, lateral view. Legs removed.

Figure 6. Formica subintegra, head, full face view.

One species found in northeastern Kansas, Lasius umbratus, has a distinct lemon aroma, especially noticeable when a nest is first disturbed. This species is thought to rely upon Lasius alienus when it establishes a colony. Although details of colony founding by Lasius umbratus in North America are poorly known, it may follow Lasius niger which has been extensively studied in Europe. A newly mated queen lands and begins searching for workers of its host species. She either encounters isolated workers or briefly enters a nest and pulls one or tow defending workers to the surface. There she proceeds to bite and eat the workers. It is thought this allows her to obtain the colony odor of her host. After several hours, the queen proceeds to enter the nest, then locates and kills the host queen. She deposits her own eggs in the invaded nest and the host workers rear her offspring. Since no additional host eggs are laid, the host workers age and die off. Eventually, a pure colony of Lasius umbratus develops. This approach to starting a colony may be an adaptation to cold climates; the parasitic queen does not need to spend as much energy rearing her first offspring. Indeed, queens of this species are much smaller than the host queen which may reflect less need to store nourishment to feed developing offspring.

Another species is even more dependent on the host species. Formica subintegra lives in open woods and sunny meadows. Besides entering a host colony of Formica subsericea and killing the queen, these ants depend on their hosts throughout their life cycle. Once worker offspring have developed in the host colony, they begin raiding other colonies of the host species and carry of pupae. Captured pupae develop into worker ants which begin to care for the parasite ant. Ants that emerge from the kidnapped pupae form an image of their nest within the first few hours of adulthood. They accept their captors as nestmates and even accompany them on raids on nests of their own species.

Workers of Formica subintegra have an enlarged Dufour's gland in their abdomen. They produce decyl, dodecyl, and tetradecyl acetates which they spray during their attack on a host colony. Wilson calls these "propaganda substances" since they evaporate slowly, exert their influence over a period of time, and alarm and disperse the defending workers. These chemicals attract attacking nestmates of Formica subintegra.

In many instances, the attackers move their nest into the raided colony. Ants usually raid in the afternoon and have been known to raid every day in eh summer. Once raided, Formica subsericea workers typically attempt to block their nest entrances with bits of grass, pebbles, or soil particles.

Another species, Polyergus breviceps, has evolved scimitar shaped mandibles (cover). These are highly effective for fighting and piercing their opponents, but are so ineffective as mouthparts that these ants are dependent upon their hosts to feed them. Experiments with isolated workers suggest they will starve to death when surrounded with food unless a host worker is available to feed them. There are a number of parasitic species in the Midwest and Plains regions and most have been poorly studied.

Figure 7. Crematogaster punctualata, head, full face view.