INTRODUCTION
Acrobat ants include several species. Their common name is descriptive of this ant's habit
of raising the abdomen over the thorax and head, especially when disturbed. Various
species are found throughout the United States, including at altitudes of up to 8,000 feet
(2438 m).
RECOGNITION
Workers monomorphic, about 1/16-1/8" (2.5-4 mm) long; queens range up to
3/8" (10 mm) long. Color light brown to black, sometimes multicolored. Antenna 1 1
-segmented, with 3-segmented club. Thorax with 1 pair dorsal spines. Pedicel 2-segmented,
attached to upper side of gaster. Gaster heart-shaped in dorsal view, broadest towards
thorax and sharply pointed at rear. Stinger present. Workers of many species emit a
repulsive odor when alarmed.
SIMILAR GROUPS
- Leafcutting ants (Atta spp.) with 3 pairs of dorsal spines
on thorax, pedicel attached to middle of gaster in lateral view, and gaster not
heart-shaped in dorsal view.
- Other 2-node ants with pedicel attached to middle of gaster
in lateral view and gaster not heart-shaped in dorsal view.
DAMAGE AND SIGNS OF INFESTATION
Often the only exterior indication of damage (") is the accumulation of
debris expelled by these ants, especially if the debris is styrofoam insulation. They
prefer wood softened by decay fungi or styrofoam insulation, but may enlarge cavities in
wood made by other insects. They will occasionally strip the insulation from electrical or
telephone wires which can cause short circuits.
BIOLOGY
Little has been published on acrobat ant biology. Most structure-infesting
species are described as nesting in moderate to large colonies. Probably the most commonly
encountered species is C. lineolata (Say) with workers 1/8" (3-4 mm), males 1/8"
(3.5-4 mm), and females 1/4-3/8" (7-8 mm) long. This species varies greatly in color
and nests up to 5,000 feet elevation (1,700 m) in the Blue Ridge Mountains. Many of the
species, including C. lineolata, tend aphids and will build carton sheds to cover them.
Similar sheds are built by C. lineolata and used as brood/rearing chambers. Swarmers have
been observed in nests or swarming from mid-June to late September; in North Dakota on
July 18th, in Colorado from July 4-August 51h. The odor emitted by C. lineolata resembles
mammalian feces.
HABITS
Inside structures acrobat ants typically nest in wood which has been subjected to
high moisture and fungal decay, the same wood conditions favored by carpenter ants.
Similarly, they will nest in styrofoam insulation panels and in wall voids. Outside most
species nest under rocks, or in logs, firewood, or trees where decay enables them to
tunnel under the bark and/or into the wood. They occasionally will nest in abandoned
termite and carpenter ant galleries as well as in old wood borer, powderpost beetle, or
wood wasp tunnels.
The workers readily enter structures by trailing along tree
limbs and utility lines as well as along the rails of connected fences and decks. They
then enter via cracks and holes around utility lines/pipes, window frames, soffits, etc.
Workers also will trail across the ground and enter via door thresholds, weep holes, and
other openings or cracks. They have been found to trail over 100 feet (30.5 m).
Acrobat ants feed on honeydew from aphids and mealybugs
which they usually tend or "herd." They also feed on live and dead insects,
including termite swarmers. Indoors they show a slight preference for sweets and
high-protein foods such as meats. When disturbed or alarmed, workers of all but the
smallest colonies tend to be quite aggressive. They are quick to bite, and give off a
repulsive odor.
