Controlling Bachac And Biting Ants In Citrus Orchards

Bachac 

Bachacs, also called leaf cutting ants, are one of the most destructive insect pests of citrus in Trinidad. They damage leaves in mature trees which can reduce yield. Severe infestations can lead to the death of young citrus seedlings.

There are only two species of bachacs in Trinidad: Atta cephalotes and Acromyrmex octospinosus.

Atta cephalotes 

The Atta cephalotes or the forest bachac as it is commonly referred to, has a shiny appearance, is reddish-brown in color and has long slender legs. This species is more likely to be found in citrus orchards which are located near to forested areas.

Acromyrmex octospinosus

Acromyrmex octospinosus or the savannah bachac is the more common of the two and is the one usually found in citrus orchards. They live in colonies in underground galleries and chambers. Their nests can be identified by the mounds of loose earth found at the entrances to the underground tunnels.

A large nest can house as many as 5 million bachacs.

Acromyrmex octospinosus are generally smaller than Atta cephalotes and vary in color from brown to almost black with shorter legs. In comparison to Atta cephalotes this species harvests a wide variety of vegetable matter, making it even more difficult to control.

How To Identify Bachac Damage 

Bachacs prefer young leaves. They cut off pieces of young leaves in a characteristic semicircular or half-moon shape. Bachacs do not feed on the leaves which they cut and carry away to their nests. Rather, they feed on a fungus that they cultivate on these leaf pieces.

Regularly examine citrus fields for this type of damage to leaves to detect their presence for timely control. In many instances the insects can be seen transporting the leaves.

How To Control Bachac 

The most effective method of control is by using a commercially available bachac bait which contains fipronil as the active ingredient. When bachac-damaged leaves are observed, place the bait in a dry hollow container such as a short piece of bamboo or PVC pipe 2 inches (5 cm) and 15 inches (38 cm) long in the path of the insects near to the affected trees. Gloves or scoop should be used to avoid touching the bait with bare hands. The bachac will take the poisoned bait inside the nest and the entire colony will be destroyed.

TIP: Touching the bait with bare hands taints it making it less effective and exposes the user to harmful poison.

Biting Ants (Azteca sp.) 

Biting ants build their nests on the underside of citrus branches. They inflict very irritating bites on field workers during harvesting and pruning operations.

These ants strip the bark at the base of seedlings. They also protect scale insects from which they obtain honeydew. Honeydew encourages the growth of a black sooty mold (a fungus) on citrus trees.

How To Control Biting Ants In Orchards 

Spray with a contact insecticide containing alphacypermethrin before carrying out field operations. For trees with large nests, remove the nests with a cocoa knife and rod, cut up the fallen nests in small pieces, then spray the trees and nest with the insecticide.

How To Manage Biting Ants In Home Garden

• Use equal parts of sugar and baking powder. Place around ant- infested area and nests.
• Pour half cup of Epsom salts into the nest and all around it.
• On smaller plants, a bit of petroleum jelly smeared around the base stops ants from climbing onto the plant.