The term “wood ants” is used to describe 2 types of ants: true wood ants and wood-infesting ants. Despite being called the same name though, these 2 types of ants are very much different.
For example, true wood ants refer to soil-nesting ants from the Formica rufa species group while wood-infesting ants refer to the likes of carpenter and moisture ants which are known to infest and damage wood.
In this article we’ll primarily discuss what true wood ants are as we discuss in more detail how to identify them, their colony structure, and habits. That said, we’ll also look a bit into wood-infesting ants to further understand how both types of wood ants differ.
True Wood Ants
True wood ants are again, soil-nesting ants from the Formica rufa species group, a subgeneric group within the genus Formica. Otherwise known as thatch, mound, or field ants, these ants get their name from their red and brown-black color and their preference for woodland or forest habitats.
They’re especially known for nesting in soil and building prominent thatched mounds that consist of organic materials including grass, litter, pine needles, twigs, and moss.
Identifying True Wood Ants
Wood ants are reddish-brown ants with black patches on their heads and abdomens. They’re polymorphic or have workers that vary in size which measure between 4.5 to 9mm (0.14-0.35 in) in length. Queens can measure up to 12mm (0.47 in) in length.
True wood ants also have long erect hairs on the upper surface of their heads and abdomens. Lastly, they have large mandibles and are capable of spraying formic acid.
The colony structure of wood ants varies between each species of the Formica rufa group. Some species are monogynous or have one single reproductive queen, while some like the Japanese wood ant (Formica yessensis) are polygynous and can have more than a hundred queens in a colony.
Regardless, each wood ant colony typically contains 100,000 to 500,000 ants. However, their nests may sometimes be interlinked and in extreme cases may form colonies of more than 400 million wood ants covering an area of more than 2.5km2.
Wood ant colonies can be founded in one of the three following ways:
Dispersal: Dispersal refers to reproductive strategy involving the dispersal or nuptial flight wherein drones and virgin queens swarm to mate. After swarming, successfully mated queens then make their way to safety, seal themselves off, and start producing workers to start an independent colony. This reproductive strategy typically results in a monogynous colony structure.
Budding: Budding on the other hand, is a reproductive strategy that occurs with polygynous ants. This happens when queens mate around their maternal nests, return, and then eventually break out with a group of workers to form new nests.
Social Parasitism and Colony Takeover: Formica ants are known to be social parasites. In fact, research has identified three types of social parasitism in wood ants, one of which is called temporary parasitism. In temporary parasitism, wood ants invade a host nest to kill the resident queen(s). Once they do, the parasitic queen then lays eggs and tricks the host worker ants to raise her offspring. Eventually, the host workers die and the colony will be fully taken over by the parasitic ants.
Where Do True Wood Ants Live?
Wood ants can be found in the United States but are more widely distributed around Asia and Europe. They typically live and build their nests in woodlands, such as coniferous, mixed, and broadleaved forests.
These nests protect the colony from predators and the elements. They’re characterized by large mounds that can grow up 2 meters tall and just as deep underground. In these mounds are interconnected tunnels and chambers which may serve as resting areas or contain the queen, her brood, and the colony’s food stores.
Wood ant mounds are thatched or are covered with organic material such as grass, litter, pine needles, twigs, and moss which helps regulate temperature and keeps the mound dry in the rain. This allows the mounds to provide an ideal environment for brood growth and development.
What Do True Wood Ants Eat?
True wood ants, as with many other ants, are omnivorous and eat both plant and animal matter. They eat small invertebrates which they hunt down and capture using either their pincer-like mandibles or the formic acid which they can accurately spray from their gasters.
True wood ants also like to eat sweet substances like honeydew. In fact, wood ants are known to build mutualistic relationships with honeydew-producing aphids. They farm and milk these aphids for honeydew and in return protect them from predators.
On the flipside of things, wood ants may also refer to a group of wood nesting or infesting ants. These ants are regarded as pests as when left unchecked, they can cause severe structural damage to wooden structures and property.
This group of wood ants include the ever notorious carpenter ants, moisture ants, and velvety tree ants.
Carpenter ants are the most notorious of the wood-infesting ants. They are part of the globally distributed genus Camponotus, a genus represented by more than 1000 species living in a variety of habitats. They are large and usually dark ants that can be yellowish red, solid black, or a combination of black, red, or reddish orange in color.
Carpenter Ant Nests
Carpenter ants typically nest in wood but may also build nests in soil. They prefer to nest in moist wood which favors growth and development and as such, are more likely to be found in rotting wood particularly those that have been damaged by water.
They also may establish nests in different locations. These nests may either be the parent or satellite nests which vary in colony structure. Parent nests, when mature, contain the members of the colony that require more care such as the reproductive queen and her brood. It also contains a good number of workers that support the queen and take care of her young.
Satellite nests on the other hand, only contain workers, swarmers (virgin queens and drones), and older pupae or larvae. These satellite nests can be built around areas with relatively less moisture and even in dry wood.
What Do Carpenter Ants Eat?
Carpenter ants are omnivorous insects and eat different types of food. They feed on worms, insects, and sweet sugary substances such as nectar, syrup, honey, and honeydew. Contrary to popular belief, carpenter ants don’t eat wood.
Moisture ants refer to another group of wood-infesting ants from the genus Lasius. These ants are small and have yellow to reddish-brown coloration.
They’re commonly mistaken for carpenter ants due to their inclination to exploit and excavate damp wooden structures. Like the latter, they can do significant damage to wood if left unattended.
Moisture Ant Nests
Like carpenter ants, moisture ants build their nests in wood. Unlike the former however, moisture ants can’t excavate dry wood and therefore, only nest in rotting wood or those softened by moisture.
What Do Moisture Ants Eat?
Moisture ants have the general omnivorous ant diet. They eat everything from sweet sugar substances like floral nectar and honeydew to insects and other arthropods.
Velvety Tree Ants
Lastly we have the velvety tree ants of the Liometopum genus. These ants have brownish-black heads, yellowish-red thoraxes, and black abdomens covered with fine velvety hairs. Like moisture ants, they too are commonly mistaken for carpenter ants because they invade and nest in wood. In fact, they’re commonly associated with tree hollows, stumps and logs.
Apart from being wood-infesting ants, velvety tree ants are also known to be aggressive with painful bites. They also produce a distinct foul-smelling odor when crushed.
Velvety Tree Ant Nests
As with the other wood-infesting ants, velvety tree ants also nest in wood. In particular, these ants usually nest in trees, hence the aforementioned association. When indoors, they’ll nest in areas with high moisture such as wood damaged by leaks.
What Do Velvety Tree Ants Eat?
Similar to the two other wood-infesting ants, velvety tree ants are omnivorous and eat both plant and animal matter. They mostly eat honeydew produced by aphids and mealybugs that live in the same trees as them.
Overall Differences Between Both Wood Ants
The differences between both ants are quite obvious. Apart from the name and being omnivores, true wood ants and wood-infesting ants don’t seem to have much in common. They come from different genera, look different from each other, and exhibit very different nesting habits.
Summary: What Are Wood Ants?
Wood ants may refer to either true wood ants or wood-infesting ants. True wood ants are ants of the Formica rufa species group and are called wood ants due to their reddish-brown and black color and their tendency to nest in woodlands. Wood-infesting ants on the other hand, as their name suggests, are called wood ants due to their tendency to nest in wood.
These two types of wood ants are very much different from each other in terms of appearance and nesting habits.