The Ants of the Pacific Northwest
Ants are perhaps the most successful of all insects. There are approximately 8,800 species worldwide. With about 580 species in North America, of these, 83 are found in B.C.
In most areas of the world, they are among the most dominant of Insects. But it is not in terms of diversity where they dominate, but rather in numbers, in many areas they make up a large portion of the overall insect population.
Most people have encountered them in a negative context, such as discovering them in your home. They can be serious pests in some areas. However, they are a key factor in ecosystem function and their removal would seriously alter its ability to function and many other organisms would be impacted negatively.
They are also a staple food for many birds such as woodpeckers and they are an important dietary component for bears. For example, ants and their larvae are the main food source eaten by bears during the early spring. Bears will search for them quite actively during this period. On Vancouver Island, black bears depend on them throughout late summer and fall when the berry crop is poor.
Carpenter ants are among the dominant in sub boreal forests, where they are perhaps the most important organisms in physically breaking down wood.
Many species are fierce predators and as such can be beneficial. Some species like thatching ants can have huge nests, containing many thousands of workers, so they could have a significant impact on forest health by preying on the caterpillars of defoliator moths, at least in B.C.
They can affect their environment in many ways. Some species have been shown to surpass earthworms in the amount of soil they transport to the surface.
Many plants have evolved to have their seeds dispersed by ants. Many species farm aphids and their relatives for their honeydew. In return, the aphids are protected by them from predators and parasites. Ants sometimes actively move aphids from plant to plant like a farmer moving his herds around.
Many utilize dead wood for nest construction. The most well known of these are the carpenter ants. These large, but often shy and non aggressive ants construct their nests in decayed logs or standing trees. In a preliminary survey of ants it is found that dead wood is a preferred nest substrate for most ant species in B.C. on Vancouver Island.
The western thatching ant is a relatively widespread species on Vancouver Island. It is often locally dominant in forest stands with sandy soils. This species can construct impressive thatch mound nests. I have seen these nests get as big as 2 meters across and contain hundreds of thousands of ants.
The odorous house ant, is very widespread in North America. In spite of its diminutive size, this one can be rather aggressive. Because of its small size, it is easily overlooked. Nests are often found in association with wood, but the majority of their nests are under moss or in soil. They will also nest in any place they can hide in your home and I have even found temporary nests in electronics like radios and televisions.
The ones most commonly seen are those that occur in and around human dwellings and in cities. Carpenter ants get their name as a result of the habit of many common species to nest in wood, including human dwellings. Most commonly, people notice carpenter ants when they swarm in spring, but since nests can be quite large, workers are also noticeable around well established nests.
Many species of them invade homes, but some do this more commonly than others, the small odorous house ant, a species more or less ubiquitous throughout North America is the most common ant found in our homes on the Island. They are small black ants which scurry around and get their common name from a characteristic odor they give off.
Red ants tend to be less noticeable. The are often reddish in color, have a stinger like bees and can inflict painful stings in spite of their small size. They are usually slower moving and somewhat more cryptic with small nests, but many are commonly seen in cities where their nest entrances are located in sidewalk cracks and between paving stones.