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Carpenter ant swarms

Carpenter ants are very common in Minnesota and are frequently found infesting homes and other structures. Like other ants, carpenter ants produce a mating swarm. This is when the reproductives, females and males, emerge from a nest, typically in large numbers. They are also accompanied by some workers. They mate and the females fly off as queens to search for suitable places to start nests.

Carpenter ant swarm. Males swarm
first followed by females.  Photo: 
Jeff Hahn, Univ. of Minn. Extension
Different ants swarm at different times of the
year; carpenter swarm in spring. Carpenter ant queens are typically black and large, about ½ inch long, although some carpenter ant species are smaller and can vary in color. Males are always smaller than queens. Regardless what species the carpenter ant is, they all have a one-segmented node between the thorax and abdomen.

Could they be termites?

Some people worry that these winged insects could be termites. Fortunately, termite colonies are very uncommon in Minnesota, only occurring in the southern 1/3 of the state.
Seeing winged termites in Minnesota is rare.

You can distinguish between them as carpenter ants have a noticeable waist, elbowed antennae and two pairs of wings that are different lengths; termites do not have a visible waist, have straight antennae and four equal sized wings.

Swarms inside your home

Finding a swarm indoors means that a nest is also inside the home. The swarm also give you an idea where the nest is located, usually nearby. Make sure the ants are correctly identified as there are other ants than swarm in spring.

Carpenter ants commonly nest in wood and can potentially damage buildings. Their damage occurs relatively slowly but don’t ignore them. Controlling nests is challenging because of the hidden nature of their nests and the complexities of their biology. A professional pest management company is best able to eliminate a nest.

carpenter ants
A winged and wingless carpenter ant queen. Finding
one or two of them walking around is not a sign
of a nest.  Caption: Jeff Hahn, UMN Extension
Finding an individual queen

Sometimes a single winged or wingless carpenter ant queen is found. Her presence in your home is not an indication of indoor nest. It means she swarmed somewhere close by and is now searching for a place to start her own nest.

After a queen lands, her wings break off and she becomes wingless for the rest of her life. Because she is still searching for a favorable site, you know there is no nest there.  Once she starts a new nest, she does not leave it. The only necessary control when finding an individual queen is physical removal.

For more information, see Carpenter ants.

Author:  Jeffrey Hahn, Extension Entomologist
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