Acorn ant

Scientific Classification

Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmicinae
Tribe:	Crematogastrini
Genus:	Temnothorax
Species:	T. curvispinosus
Source: Bug Guide

Description

Temnothorax curvispinosus, or the acorn ant, is a well-studied species found in both rural and urban areas of the eastern United States. These ants have this common name because they can live in hollowed-out nuts, such as acorns. An entire colony of these ants (which can be between 100 and 300 ants) can live inside hollow nuts, like acorns. The acorn ant is amber to yellow in color, and it has 11 segmented antenna, along with a curved propodeal spine. The middle part of their body (mesosoma) is covered in rough ridges (rugae), and their heads have tiny holes, or “studs,” which are separate from their eyes. These ants are temperature-sensitive and quite small in size. Behaviorally, they have been observed to act passively.

Habitat & Range

Acorn ants are native to the eastern United States. Their range extends as far north as Maine, as far south as Florida, and as far west as Arizona. They can also be found in parts of Canada, including Ontario. They are likely to occupy temperate and subtropical northern forests.

Nesting Habits

In addition to hollowed-out nuts, acorn ant nests can be found in hollow stems, insect galls, puffballs, and pinecones. Nests may also be under rocks or in soil, usually at lower elevations. Nests typically consist of 80-100 worker ants, which are female, and sometimes contain multiple queens. Acorn ants are polydomous (meaning they can inhabit several nests), and they can thus change where they reside after any disturbance in or near a nest. In the summer, sub-colonies can form from the main colony of a nest and build a new nest nearby. During the winter, sub-colonies coalesce into one colony. But, about half of the colony is lost in the winter, as ants either die off or migrate to start or join a colony.

Reproduction

Acorn ants are polygynous. Male ants reproduce with queens inside the colony. Larvae can be found inside a nest all year-round. New colonies are formed by multiple queens (Pleometrosis), or a new queen can be adopted into an existing colony. The queen will lay around a dozen eggs in a nest. The eggs hatch into larvae, which go through multiple molting stages as they grow. Eventually, larvae will metamorphose into a pupa and then grow into an adult ant. The queen and male ants have wings while the worker ants (female), do not have wings.

Worker

Male

Queen

Diet

Acorn ants are generalists, but often eat liquid sugars like honeydew from tree and plant leaves. These ants also eat protein in the form of small insects, like spring tails and dipterans (flies). Foraging is usually done in tandem (one ant leading another ant) and is more common in the spring and summer.

Adaption

Acorn ants are temperature-sensitive, but colonies that live in urban areas have adapted to tolerate higher temperatures. The development of cities has caused a rapid rise in environmental temperatures, especially with impervious surfaces. Acorn ants had an evolutionary change in thermal tolerance. Urban ant populations have exhibited greater heat tolerance under the fast rate of temperature change, and this result was correlated with both faster rates of diurnal temperature rise in urban acorn ant nest sites and more rapid spatial changes in temperature across urban foraging areas.