Extension Logo
Extension Logo
University of Minnesota Extension
https://extension.umn.edu

Carpenter ants

Quick facts

  • Carpenter ants are very common in Minnesota.
  • They can potentially damage homes and other wooden structures.
  • The best method for controlling carpenter ants is to deliver insecticide into their nest.
  • Because their nests are hidden, it's best to hire a pest management professional (pest control technician) to treat the nest.

Identifying carpenter ants

Carpenter ants are among the largest ants in Minnesota. There are several species that may be found infesting homes and other buildings. 

How to recognize carpenter ants:

  • They have a waist with one node (petiole) and a thorax (area behind the head) that is evenly rounded when viewed from the side.
  • Workers are black or red and black.
  • Workers usually range in size from 3/8 to 1/2 inch long; one species is only 3/16 inch.
  • Even carpenter ant workers of the same species vary in size (major and minor workers).
  • Queens and males are larger than workers and have wings. Queens lose their wings once they start a new nest.
  • Queens may be as large as one inch long.

Other ants can be mistaken for carpenter ants. They have one or two nodes and an uneven thorax when viewed in profile. They usually do not infest wood.

Correct identification of the ants is important for control strategies to work effectively.

Different species of carpenter ants (males, winged females and workers) are of different sizes
Left column: winged female (top), winged male. Right column: workers of varying sizes.
Closeup of carpenter worker ant with evenly rounded thorax and one-segmented petiole. The word 'thorax' indicates the section right after the head. The word 'petiole' indicates the section after the thorax and before the last section of the ant's body.
Carpenter worker ant
Dead ant with the word 'thorax' indicating middle section behind the head, and the word 'petiole' pointing at two small sections before the larger rear section.
Non-carpenter ant worker with an unevenly shaped thorax and a two segmented petiole

Ant or termite?

Carpenter ants have dark-colored bodies, narrow waists, elbowed (bent) antennae and hind wings that are shorter than front wings (if wings are present).

Termites are very uncommon in Minnesota.

  • The workers are light-colored, have a broad waist and have straight antennae.   
  • They avoid light and are rarely seen outside of their colony.
  • Winged termites, queens and kings, are dark-colored and have wings of equal length. 
The hind wings on carpenter ants are shorter than the front wings
Winged carpenter ant
Carpenter ants can be identified by the size of their wings.
Winged carpenter ants
The wings on termites are equal
Winged termite
Termites are different from carpenter ants in that they have equal wings
Winged termite

How to detect carpenter ants

 | 

Biology

 | 

Prevention and control

 | 

Jeffrey Hahn, Extension entomologist and Stephen Kells, Extension entomologist

Reviewed in 2018

Share this page:

© 2019 Regents of the University of Minnesota. All rights reserved. The University of Minnesota is an equal opportunity educator and employer.