We occasionally get some bugs on our citrus trees (who can resist sweet fruits?) and sometimes that means ants. While we haven’t had much of a problem with them, we were curious about how to get rid of them if they started overrunning the tree. So, we did a little digging to find out more.
You can prevent ants from infesting your citrus tree by eliminating their anthill, setting bait traps, placing a sticky trap around the base of the tree, and removing their food sources—primarily aphids and mealybugs. These live and feed in the tree and secrete the sweet honeydew that ants like to eat.
So, why are ants attracted to your citrus trees in the first place, and are they bad for your trees? What can you do to get rid of ants? Let’s find out more.
Why Are Ants Attracted to Citrus Trees?
Did you have an ant farm when you were a kid? If so, it may not surprise you to learn that ants themselves are farmers. Ants that herd, also known as herder ants, are attracted to citrus trees.
Ants, like all natural organisms, are opportunists. In the case of citrus trees, they have the opportunity for a free and easy meal. Citrus trees are often home to soft-bodied insects like aphids or mealybugs.
These bugs feed on the leaves and sap of the citrus tree and secrete a sweet, sticky substance known as honeydew. This honeydew and the mold that grows on it are an ant delicacy.
To secure their supply of honeydew and make sure it stays constant, herder ants will contain and protect the aphids or the mealybugs on citrus trees.
These ants will build an anthill near the citrus tree and create a territory around it, protecting their herds from ladybugs and other predators and culling out the sick or wounded. They will even sometimes bite the wings off of aphids so that they can’t fly away!
Are Ants Bad for Citrus Trees?
Ants themselves are not bad for citrus trees, but the insects that they care for and farm are. Aphids and mealybugs pierce the leaves and stems and suck out the sap, which harms the tree and makes its foliage weak and yellow. The honeydew and the mold that grows on it are also vectors for infection.
The ants’ objective is to sustain and even grow the population of aphids or mealybugs. But since their herds have such an adverse effect on your tree, this is obviously not what you want. To take care of your ant infestation, you will need to target both the ants and their herds.
This will take care of your current problem, and hopefully keep a new ant colony from forming by your tree again.
The tell-tale signs of an infestation of sap-feeders on a citrus tree are these:
- Yellowed leaves
- Distorted new growth
- Black, sticky material on leaves and stems
- Aphids gathered on the underside of leaves or at growing points of new leaves
- Small, oval, cottony spots on foliage or stems
- Irregular bumps on the leaf’s top or underside
- Weak, easily infected new growth
In California, trees weakened by aphids are also vulnerable to Asian citrus psyllid and to the incurable tree disease that they carry called Huanglongbing, or citrus greening disease.
How to Get Rid of Ants on Citrus Trees
To really take care of your ant problem, you should combine at least two of the methods we’re going to discuss. We’re also going to concentrate on organic methods here since they’re very effective and pesticides are toxic to most, if not all forms of life (beneficial or not).
The first step to getting rid of ants on your citrus trees is to locate the anthill.
Look around the base of the tree or in a planter bed nearby. You should be able to follow the trail of ants back to their camp.
The second step is to dismantle the anthill.
An effective organic treatment for anthills is simply to pour very hot, very soapy water into the opening of the anthill. Do this slowly so that the water has a chance to infiltrate every chamber of the anthill.
To eliminate any ants that may have been outside the hill at the time of your hot water assault, you can set a trap:
- Combine 2 cups of water with 1 tsp. boric acid and 6 Tbsp. of sugar. Stir well with a disposable utensil.
- Poke holes into the lid of a plastic container, then soak two or three cotton balls in your boric mixture and place them inside of it.
- Close the lid and position the trap by the base of the tree.
The result is that the ants will be attracted by the sugar, but killed by the boric acid.
You can also apply a Tree Tanglefoot sticky trap around the trunk of your tree. This incredibly sticky substance creates a barrier that entraps any ant that sets foot on it. Using one properly involves a few steps:
- Remove any paths between the tree and the ground other than the trunk (tall grasses, overhanging branches, etc.)
- Wrap a banding material around the trunk. This will keep the oil-based Tree Tanglefoot from staining the bark of the tree, and also make application and removal of it much easier. The width of this band should be 3 inches.
- If your bark has fissures that run under the banding and create a way for the ant to bypass the sticky trap, fill those spaces in so that the ant has to walk on the trap.
- Use disposable gloves and a disposable knife to apply the Tanglefoot, as it’s sticky.
- Apply a thicker, heavier coat of Tanglefoot if your infestation is extreme, or if your tree is on the brink and needs the ants to be gone. This coat can be up to 3/32” thick.
- Apply a lighter coat if your infestation of ants is moderate or if you are maintaining an ant-free tree. This coat can be up to 1/16” thick.
- The Tree Tanglefoot will effectively trap ants and other insects until the point when it is covered with dead bugs, dust, or debris. Remove the debris by gently scraping at it until more stickiness is revealed. You may need to add more Tanglefoot on top of this to restore maximum stickiness.
- If you live in a mild winter climate, you should maintain the Tanglefoot year-round. Rotate the band between different places on the base of the trunk.
- If you live in a cold winter climate, remove the Tanglefoot and band each fall, and reapply in the spring.
Now that the ants are no longer around to protect their squishy, honeydew-secreting herds, it’s time to get rid of them!
Mealybugs and aphids can usually be washed away by a strong blast of water.
When my kaffir lime tree had aphids, I was considering purchasing products and chemicals to get rid of them. Then, I found that water is more than enough to get them off of the plant and prevent them from coming back. Sure enough, after I sprayed my kaffir lime tree leaves with a blast of water, the aphids were removed successfully and didn’t come back.
Target the tips of branches and beneath the leaves, as both of these sap suckers like to huddle up in these sheltered areas. Take care not to use water pressure that is so strong that it will tear the leaves. When I was spraying the aphids off the tree, I used a hose without a nozzle and fitted my thumb over the opening to create more pressure.
If your citrus tree is small enough, you could even spray the leaf undersides and branch tips with neem oil or Safer Soap, which are both OMRI Listed organic insecticides.
Another way to take care of the aphids and mealybugs is to release some of their natural predators into your yard, such as ladybugs, lacewings, parasitic wasps, or the aptly named mealybug destroyer, to prey on them.
However, you might not be able to save all of your trees. If certain branches are very heavily infested, it’s best to prune them off. Make sure to dispose of the pruned material right away so the insects don’t have a chance to make a break for it.
Remember to also sanitize your pruning shears before and after you prune the tree, and don’t let the blade touch the soil. These measures will help prevent any transmission of diseases to your citrus tree.
You should also prune back any branches that are touching a structure or another tree because ants could climb over onto these too.
More Tips to Prevent Ants from Taking Over Your Citrus Tree
The best tip I can offer to prevent ants (or any insects) from taking over your citrus tree is to become a diligent observer of your citrus tree, as well as your other trees and plants.
Now that you know what aphids and mealybugs look like, where they like to hide on your tree, and what their damage to the tree looks like, regularly check to see if any have taken up residence.
If you find any, spray them away or apply Safer Soap or neem oil. Remember what we mentioned earlier about ants being opportunists? The ants won’t be interested in your tree if there is no opportunity for them to find food there.
Also, make sure not to over-water your tree or other plants. Aphids and their sap-sucking friends thrive in moist areas, so plan to water in the morning instead of at night, which allows the water to be absorbed or evaporate instead of lingering on the surface of your soil. Consider deep-watering your citrus tree as a best practice.
You should also keep an eye open for anthills in and around your yard. If you find one, try and see if you can follow the ants to their hunting grounds.
They may be leaving your tree well alone and you won’t have to bother them, but you might still prefer to place ant baits or repeat the hot soapy water trick.
The Tree Tanglefoot sticky trap is an excellent method for preventing ants from getting in your tree at all. If you apply a Tanglefoot trap in spring and make sure it stays sticky throughout the season, it will protect your tree with very little effort from you.