Ants

"The greatest enemies of ants are other ants, just as the greatest
enemies of men are other men."
- Auguste Ford

introduction

Ants evolved from wasps, and have similar body structures, though are most commonly wingless. They are easily identified by their elbowed antennae and slender waists, and are typically dark in color. These insects are famous for forming large colonies that consist of millions or hundreds of millions of individuals. They are present on every landmass on earth, except for Antarctica and a few remote inhospitable islands. Ants protect and care for other pest insects such as aphids, soft scales, mealybugs and whiteflies, and feed on other pests like termites, fleas, and caterpillars, and for that reason are very important to understand and monitor in home landscapes.

Their heads hold most of their sensory organs, including compound eyes that can sense acute movement but not offer them a high-resolution image of their surroundings. There are some species that are completely blind, and others that can determine the size and direction of movement of objects that are a few feet away from them. Their antennae detect chemicals, air currents, and vibrations, as well as receive and transmit signals through touch. Their mandibles are used to carry food, manipulate objects, create their nests, and for defense. Legs and wings (if present) are attached to the mesosoma, or thorax. Their feet have tiny hooked claws that are useful for grasping surfaces and climbing. Their internal organs are located in their metasoma, or abdomen.

Quick Question: How to tell the difference between ants and termites?
Ants and termites look relatively similar to the naked eye, especially when looking at an ant that has wings. To distinguish the two, remember that ants have a narrow waist, elbowed antennae, and hind wings that are much shorter than the front ones. Termites, on the other hand, have a broad waist, beaded antennae, and wings of equal length.

Ant Behavior

Ants are eusocial insects, meaning that they cooperate, form colonies with overlapping generations, and divide their labor between different functioning groups. They typically nest in soil close to their food sources, and can also construct nests in buildings, under boards and stones, and in other protected areas. They typically eat fruits, seeds, nuts, fatty substances, dead or live insects, dead animals, and sweets. They will enter buildings seeking food, water, and shelter and seem to appear suddenly when weather conditions change.

Like all other living organisms, ants require water to survive.

Ants eat a variety of items, including nuts and seeds.

If food is left out, it's a good bet that ants will eventually find it.

Ants develop through four life stages. They begin as eggs laid by an adult queen ant, which develop into larva. The larva then pupates and transforms into an adult. In ant colonies, individuals typically develop into a pre-determined caste, which is encouraged by what type of food the larvae are given as they develop. The largest caste is the workers, which are all sterile and female. They care for larvae and pupae, defend the colony, dig tunnels, and forage for food outside of the nest. Each colony produces one or more queens (fertile females) that spend most of their time underground in nests laying eggs. Male ants are only alive and present in nests during the mating season, when both them and the queens develop wings and can mate in flight or swarms outside of the nest. They navigate using pheromones, and by physical transfer of a tiny droplet containing communication chemicals and nutrients.

Ant Species

There are 13,800 identified species of ants (with an estimated total of about 22,000 species). In California alone, there are 270 species of these tiny insects, but thankfully fewer than a dozen are significant pests in homes and landscapes. The following species are ones that are most commonly seen in California.

Camponotus spp.
(Carpenter Ant)
These ants form nests in tree stumps and wood structures, and range from 1/4 to 1/2 in. long. They are either black or red and black.

Linepithema humile
(Argentine Ant)
These ants go after sweets and proteins, and nest outdoors in shallow mounds. About 1/8 inch long and dull brown

Liometopum occidentale
(Velvety Tree Ant)
These ants also release an odor when crushed, and have brown-black heads and velvety black abdomens. They nest in deadwood.

Monomorium pharaonis
(Pharaoh Ant)
Nesting in wall or cabinet voids, behind baseboards or insulation, or outdoors in debris piles, these ants are 1/16 inch long and honey-colored.

Solenopsis invicta
(Red Imported Fire Ant)
These ants make their homes in mounds and sometimes in walls, and 1/16-1/5 inch long. They are reddish with dark brown abdomens.

Solenopsis molesta
(Thief Ant)
These ants prefer greasy, fatty foods and will steal food and larvae from other nests. They form colonies in soil, under rocks and wood, and in walls or under baseboards in homes. They are 1/32 inch long and are yellow to light brown.

Solenopsis xyloni
(Southern Fire Ant)
From 1/8 to 1/4 inch, with amber heads and thoraxes and black abdomens. Nests in small mounds in wood or under rocks. Eats proteins and sweets.

Tapinoma sessile
(Odorous House Ant)
These are 1/8 inch long, dark brown-black and shiny, and release a strong odor when crushed. They nest in shallow mounds, walls, and warm areas.

Tetramorium caespitum
(Pavement Ant)
These ants make nests in lawns or under objects and also create mounds. They are 3/16 inch long and dark brown to blackish.

Ants in the garden

There are many roles that ants play in the garden, including as pest control (as predators), soil improvers, and as a small but mighty clean-up crew for debris in the landscape. Most species are not bothersome, and are rarely or never pests. In the garden, they are primarily interested in insects that produce food for them, called 'honeydew'. This byproduct is excreted by pests such as aphids, whiteflies, scale, and mealybugs, all of which have the potential to do considerable damage to plants. Ants will take on the job of protecting, consuming, and in some cases, cultivating, these other organisms for the purpose of maintaining a consistent food supply for their nest.

Unfortunately, ants protect some of the more damaging pest species in the garden.

Ants will eat the waxy covering around peony buds and help them to fully bloom.

Ants have formed a symbiotic relationship with scale insects.

Ants are an integral part of the garden ecosystem, distributing needed nutrients through soil and helping to carry out natural processes. There are many advantages to having ants in the landscape, including:

Increased Decomposition
Ants may be small, but they can provide a strong, motivated workforce to locate, break up, and feed on decaying leaves and dead insects (and animals). They break down this organic matter into the soil, making it available to organisms farther down the soil food web. Think of them is mini fertilizing machines for the garden.

Free Pest Control
Although ants do protect some of the more annoying pest species of the garden, they also help to control some insect species. They will consume insect eggs, stopping harmful pests from reproducing and damaging plants. They can also hunt down and eat caterpillars, which prevents them from consuming fruits or plant leaves.

Soil Aeration
Ants aerate soil as a side effect of their movement through it. They commonly dig tunnels in the ground, allowing more oxygen to reach plant roots. Tunnels will also have the added benefit of increasing water drainage capacity of soils, especially clay or compacted ones.

Critical Assistance
Ants act as plant life assistants, able to disperse fallen seeds father away from parent plants to other areas of the landscape. Colonies will feed on the outer shell of seeds, and discard the inner portion, which is then free to sprout and form a new plant.

Although ants are generally considered to be forces of good in the garden, some of their behaviors can interfere with our landscaping in both small and large ways. They can also be pests of homes or other structures. Ants can encourage the growth and development of pest species that produce honeydew. Many insects feed by sucking out the juices from plant stems and leaves, and the byproduct they create from this feeding is a substance comprised of sugars and amino acids. Ants love this byproduct, so much that they will go to great lengths to protect the species that produce it. In addition, they will also eat plant leaves, which can destroy foliage and reduce crop yields. Leaves are essential to plants due to their photosynthetic power, and loss of foliage can lead to poor plant growth. Finally, some species of ants can pose an issue in residential areas due to their proclivity for destroying wood. They can destroy entire wooded areas if their population grows too large, and when all outdoor sources of wood are broken down, they will move to other structures, like outdoor wood furniture and the foundation of homes. If ants are posing an issue in the landscape or in the home, it is very important to know how to manage them.

It is a futile effort to attempt to completely remove ants from the landscape. Management should be focused on areas where ants are acting as pests, such as when they are tending honeydew-producing species, are damaging plants, or if they are abundant near structures like homes. To manage and control populations of ants in garden and home spaces, follow these guidelines:

Monitor Hot Spots
Where ants or honeydew-producing pests have been an issue in the past, inspect the trunks and branches of those plants in late winter or early springtime. Also, inspect the soil around the base of the plant and look for ant trails. It is best to look for ants during the warm times of the day in cool weather and cooler times of the day during hot weather.

Keep Things Tidy
Remove irrigation water, leaf litter, mulch and vegetation at least several inches back from the foundation or walls of buildings where ants are not welcome visitors. It will discourage them from finding small entryways into the structure, which will keep them from causing any structural damage.

Manage Pest Populations
Ants are huge fans of honeydew, excreted by various organisms including Aphids, Mealybugs, Scale, Whiteflies, and Psyllids. If the populations of these garden insects are controlled, ant populations will not have the energy needed to form large colonies in the landscape.

Seal It Up
Ants enter buildings through very tiny cracks and crevices. To exclude ants from interior spaces, make sure to seal every crack possible. It is also suggested to add weather stripping to doors and windows to help them seal more tightly, as well.

Insecticide sprays formulated for ants should not be used in the home garden. They are not very effective, killing only the foraging ants that leave the nest. They also commonly contain pyrethroids, which are blanket insecticides that kill a wide variety of insects, including beneficials, in the landscape. Baits are typically the most effective against ants, and have the potential to kill entire colonies without contaminating the garden with pesticide. Baits must be slow-acting to be truly effective. They do require some patience, but provide longer control of ants than sprays do. For the most economical treatment of ants, put out traps in late winter or early springtime, before ant populations explode for the year. Situate them near any nests that have been identified, at the base of plants frequented by ants, and along foundations or walls where ants have been observed inside. Never put bait traps indoors; this will only encourage more ants to come inside the home.

Bait stations can be single-use or refillable and reusable. Single-use bait stations can be used anywhere outdoors, and require users to remove a piece to open up the bait to ants. Reusable, refillable stations, on the other hand, require the mixing of sugar water and the insecticide. Slight changes in the makeup of the products included in these bait stations can dramatically reduce their effectiveness, For example, Boric acid concentrations higher than 1% are less effective than products with 0.5% to 1% boric acid, because higher borate concentrations repel ants.

Another option for exclusion of ants from certain areas are sticky barriers. These physical barriers are wrapped around trees or the trunks of other plants to prevent ants and other wingless insects from climbing to reach the twigs and leaves. These products are more effective when they are applied above where irrigation can reach. Avoid applying them horizontally; they can inadvertently harm roosting birds. Check these traps every few weeks, and replace as necessary. A trail of dead ants can provide a great bridge for ants to cross over.