Extension Communications
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
7/22/02
Contacts:
Donald Lewis, Entomology, (515) 294-1101, drlewis@iastate.edu
Jean McGuire, Continuing Education and Communication Services, (515) 294-7033,
jmcguire@iastate.edu
Yard and Garden Column for the Week Beginning July 26, 2002
Why Do Some Ants Have Wings?
Donald Lewis
Extension entomologist
Iowa State University
A very common question at this time of the year goes like this: "I
just saw an insect that looks like an ant, except that it has wings. What
is that?"
I tell these callers, "If you think an insect looks like an ant,
it probably is an ant. And yes, some ants do have wings and we have a
technical term for ants with wings. They are called 'winged ants.'"
All ants have a "pinched" waist at about the middle of the body that distinguishes them from most other insects, including termites. Both the typical wingless ants and those with wings have pinched waists. If you look closely you also can see that ants have bent antennae that form an elbow-like joint near the middle.
Nine Thousand Species
There are approximately 8,800 different kinds of ants. There may be thousands
more species not yet discovered. The estimated number of different kinds
of ants in North America (north of Mexico) is a mere 580 species, and
in Iowa, we have no more than 100 species.
Ants are social insects. That is, like some bees, some wasps and all termites, ants live in complex societies with three defining characteristics: the adults care for the young; there are two or more generations of adults in the same nest and there is a division of labor. Division of labor means some individuals are equipped only for certain jobs, a role they perform for the good of the colony. Specifically, social insects generally have a large number of nonreproductive workers that provide and care for reproducing royalty.
The ants have a complete life cycle of four stages: egg, larva, pupa and adult. Most people are familiar only with the adult, the lone stage to exist outside of the colony nest. Eggs, laid by the select few queens, produce wrinkled, white, legless grubs (larvae) that must be nurtured by adult ants to survive. The nonreproductive adults (workers) scour the vicinity of the nest for living or dead insects, nectar, plant matter or other food appropriate to the species and bring it back to feed the helpless larvae. After several weeks as a larva, the individual forms a protective silk cocoon and makes the transformation to the adult stage.
Almost all of the adults emerge as sterile, wingless females called workers. These workers set about doing the manual labor of the colony, cleaning and enlarging the nest, foraging for food, feeding and caring for the larvae and defending against invaders.
But what about winged ants?
When an ant colony is well established and sufficiently vigorous, a different
group of adults emerge. These are the sexually developed, winged male
and female ants that people notice.
Winged ants are also called swarmers. These emissaries are produced only when the colony has reached a stage where there are resources to spare. Swarmers depart from the established colony on a mission to initiate new colonies. They have very, very slim chances of success. Most die of starvation, dehydration or are eaten by birds, dragonflies or other predators. Although almost all fail, just enough succeed to spread the species and ensure its survival.
Departure of the swarmers may mean death to most of them but it does not mean the death of the original colony. Workers in a healthy colony go on about the work of being an ant while building up colony numbers and strength in preparation for the next big swarm.
Swarming occurs at different times for different species and each species has a rather predictable time when the swarmers occur. Foundation ants and field ants, for example, almost always swarm in the fall, starting about the time of the end of the Iowa State Fair. Watch for them filling the air at dusk.
What does swarming mean to me?
Winged ants are often the most visible sign of an ant colony, but they
are harmless. They are not the individuals that did the work of creating
mounds in your lawn, dirt piles on your driveway or sawdust at the base
of your hollow tree. Swarming is a temporary, natural event and is not
a permanent or major problem. Besides, swarmers are often beneficial as
an important link in the food chain. Outdoors, ignore them if possible.
Winged ants may be a nuisance or annoyance if they emerge in the house (or wander indoors during their swarming activities). Still, there is little justification for treating winged ants beyond sweeping or vacuuming them up for disposal.
When ant control is necessary, direct nest treatment or baiting to control the wingless workers and the egg-laying queen within the colony is effective. Swarming may be your indication of the colony location. It also might be your wakeup call to start looking for an established colony that might be a problem.
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