A few ants on or around trees and other plants is normal and unlikely to cause a problem, but a large number of ants on a tree may indicate an infestation of honeydew-producing insects. Using sticky barriers on the tree can eliminate the need for potentially toxic chemicals, making these barriers a smart choice for controlling ants on trees in areas where children or pets play. You can use a commercially available sticky material or petroleum jelly to create a sticky barrier to trap ants.
Applying a Sticky Barrier
It's a good idea to apply the sticky material out of the reach of children -- even if the material is nontoxic, it can still create quite a mess. Apply the sticky material to the tree with a putty knife, ice pop stick or a similar utensil to spread it out. Create a uniformly thick band of sticky material about 4 inches high around the entire circumference of the tree.
Young or thin-barked trees may be damaged by sticky material applied directly to the tree bark. If you are worried about potential injury to the tree, first wrap a band of fabric or paper around the tree, tying or taping it in place, or make a band of tape with the sticky side out. Don't make the band too tight, as this can injure or girdle the tree. Apply the sticky goo to the banding material. If there are gaps under the fabric because the bark has ridges or is otherwise uneven, stuff cotton batting tightly into the gaps.
Monitoring and Maintenance
Debris or ant bodies stuck in the sticky barrier can create a bridge that renders the barrier ineffective. To prevent this, check the sticky barrier each week. If there's a lot of debris, use a stick to stir the material. You can also add more sticky material or replace it. The sticky barrier will naturally degrade after a few months. In areas with cold winters, remove the banding and sticky material in fall.
For the sticky barrier to effectively keep ants out of the tree's canopy, there must be no other route for ants. Prune off any branches that touch fences, walls or other plants, making any pruning cuts slightly angled and just above a bud or branch junction. If the canopies of several tall trees are touching, it may be easier to band each tree.