When you think of carpenter ants, you no doubt picture a bunch of little ants destroying the walls of your home. However, this is only the tip of the proverbial iceberg.
In reality, carpenter ants (Camponotus spp.) don’t feed on wood like termites, which can often be a major problem outside your home.
But the odd thing is that very few resources about carpenter ants bother to mention the potential damage they can do to your garden.
How To Identify And Get Rid Of Black Carpenter Ants?
There are nearly 1,000 different carpenter ant species, but perhaps the black carpenter ant is the most well-known (Camponotus pennsylvanicus).
Here’s what you need to know to reasonably identify these ants and get them out of the garden.
What Do Black Carpenter Ants Look Like?
Black carpenter ants have a distinctive dull black exoskeleton with yellow to whitish hairs on their abdomen.
Queens can be up to 0.8 “inches long, with majors measuring 0.66” inches and workers ranging in size but smaller than the majors.
A single colony can number in the thousands, and the clacking of the workers can sometimes even be audible.
Alates tend to have a yellowish hue to their wings.
Black carpenter ants are found throughout the northern US and are known to be more likely to invade homes than many other species.
What Do Black Carpenter Ants Eat?
Carpenter ants don’t eat wood but need proteins and sugars.
For proteins, they commonly consume dead insects, but it’s the sugars that should be of concern to gardeners.
Black carpenter ants sometimes feed on plant sap but often raise aphids like cattle.
Smaller workers are in charge of harvesting, with larger workers carrying the honeydew produced by the aphids back to the nest.
Meanwhile, the majors help to defend the aphids alongside the workers.
How Black Carpenter Ants Harm Gardens?
As you may already know, aphids are tiny piercing insects that feed off plant sap.
Their frass (poop) is known as honeydew, a sugary substance made up of partially digested sap.
This sap is a prime breeding ground for several common fungal infections such as powdery mildew and sooty mold.
In large numbers, aphids can cause extensive damage to crops and ornamentals, although it’s unlikely the aphids will directly lead to a plant’s death.
In normal situations, the aphid population is controlled by many beneficial insects, such as ladybugs and parasitic moths.
However, the carpenter ants will actively defend their aphid cattle from predators and sometimes even target pollinators that land on the plant. Check out this article on aphids and ants.
Not only does this harm the plant’s health and increase the risk of disease, but the plant can suffer stunted growth and may fail to bloom, and any pollinators that visit it could be at risk.
Locating Black Carpenter Ant Nests
These ants can be difficult to track down because they’re primarily nocturnal.
However, they follow chemical trails much like any other pest.
When you locate a plant suffering from an aphid infestation, check for any signs of large black ants.
You’ve likely found black carpenter ants if you see smaller ones tending to the aphids and larger ones running up and down the plant.
Follow the line of larger workers as they leave the plant, and they’ll guide you straight to a colony entrance.
Eliminating Black Carpenter Ants From The Garden
There are several tactics for getting rid of a black carpenter ant infestation, and a combination of methods will often work best.
Here are some of the most effective methods.
Chemical Insecticides
Chemical methods may not be as safe as natural methods, but they can often work more quickly.
There is a wide range of insecticides out there that work on carpenter ants, including:
- Sprays
- Bait traps
Do a little research before picking one to ensure it doesn’t target any insects you are trying to encourage in the garden when buying a spray.
Diatomaceous Earth
Food-grade diatomaceous earth (DE) should be a staple in any arsenal.
This non-toxic bug killer is made from the crushed fossilized shells of microscopic diatoms. Learn more in this article on Diatomaceous Earth for ants.
Sprinkle DE around the opening of the ant nest or along ant trails.
As ants walk over it, the shells will lacerate their exoskeletons, resulting in them dying of dehydration.
You will need to reapply the DE every few days as it can be washed away from rain and moisture.
This simple treatment can help reduce the ant population and cause them to look elsewhere for food.
Homemade Bait
Black carpenter ants need protein and sugars, so why not make your own poison bait?
Simply take a cup of peanut butter and add one teaspoon of boric acid.
You can also sweeten the deal by adding a bit of confectioner’s sugar or honey to the blend.
Mix well and lay small bits of it on scraps of wax paper near the nest entrances or ant trails.
You’ll need to keep your children and pets away from the bait, and making little protective covers for the bait can help prevent wildlife from getting to it.
The ants will carry the bait back into the colony, destroying the digestive systems of any ant that eats it, including the queen.
Neem Foliar Spray
This all-natural spray uses clarified hydrophobic neem oil, a processed form of neem oil that is more gentle when sprayed on plants.
You can buy the sprays commercially or make your own.
Always apply them at dusk or dawn to minimize the risk of harming beneficial insects.
Spray the infested plants thoroughly, also ensuring to get the undersides of the leaves.
Repeat every other day for 14 days or until the infestation is gone.
In this form, neem suffocates insects on contact, including aphids and ants.
This won’t eliminate the black carpenter ant colony on its own, but it can reduce the population and eliminate one of their major food sources.
The Benefits Of Companion Planting
Finally, companion planting is a great preventative measure that will work against a wide range of pests, including black carpenter ants.
Companion planting is the practice of mixing plants that have specific benefits into your garden.
Some great options to fight these ants include lemongrass and peppermint, although rosemary, sage, and cloves can also do a great job of keeping them away.
The strong scents of these plants override the ants’ scent trails, making it hard for them to reach food and isolate ants, making them easier for natural predators to pick off.