Living with Ants in the Garden

Ants are an amazing species.  It is estimated that ants may make up as much as 15% – 25% of the terrestrial animal biomass.  That’s a LOT of ants.

There are indigenous ant species on every continent except Antarctica.  There are 260 species of ants in Texas.  Several species are with us in our gardens, so we need to spend a bit of time learning how to coexist with them.

Friend or foe?

In general, ants are considered beneficial insects. Their tunneling activity mixes and aerates the soil.  There are ant species that are carnivores, others that are herbivores and many that are omnivores.  Some species are part of nature’s waste management system.  Other species are beneficial predators, feeding on other insects that are serious crop pests.

Ants are an important food source for birds, reptiles, and some mammals.  Only a handful of ant species are considered household or garden pests.  There are two serious pest species in Texas; the Red Imported Fire Ant (RIFA) and the Rasberry/Tawny Crazy Ant.  Both are invasive, non-native species.

Native Ants

Not all ants deserve pest status.  Native Ants should be learned and appreciated.  They can compete with the invasive species to a certain extent if we give them half a chance; which means carefully targeting the pests and doing all we can to avoid killing off any ant that is not a true household or garden pest.

We should just observe our Native Ants and leave them alone with the exception of keeping them out of our homes and outbuildings.  Ones you will commonly see are Pyramid Ants, Big-Headed Ant, Pharaoh Ants, Carpenter Ants, Leaf Cutter Ants, Harvester Ants, and Little Black Ants.

The Lesson of the Ant and the Toad

Some ant species are vital to the survival of other valuable species.  The Horned Lizard (Horny Toad) is one example.

Until the last two decades, the Horned Lizard was a childhood favorite of many Texans.  Horned Lizards feed on Red Harvester Ants, each consuming 20 – 100 per day. The ants provide formic acid, a necessary nutrient for the lizards.  But the Red Harvester Ant population is being decimated by human activity.  The dramatic decrease in their presence has had a devastating impact on Horned Lizard populations, placing them on the threatened list.

Two major factors have impacted the Red Harvester Ant.  One, their preferred food source is weed seeds, which have been reduced in developed areas primarily due to turf installation and management practices.  Two, they are suffering from mistaken identity.  People often confuse the Red Harvester Ant with RIFAs and treat their mounds unnecessarily.  Red Harvester Ants do sting, but they are easily avoided.  Treatment is seldom, if ever, necessary.

As the Red Harvester Ant population drops, the gap is being filled by the invasive RIFA.  Young Horned Lizards easily fall prey to foraging RIFAs.  So in addition to losing their food source, they are struggling to raise their young to reproductive age.

The end result of this chain of events is that the Horned Lizard has virtually disappeared in areas now dominated by the RIFA, which is then blamed for their demise.  But it is also disappearing from areas not yet dominated.  The fact is, RIFAs are a part of the decline, and are definitely hindering any hopes of recovery, but human activity thumped the first domino.

Finding the balance

In order to enjoy our yards while keeping children and pets safe from serious ant stings, we have to find a way to manage the RIFA.  Management means reducing their populations to something we can deal with.  It does not mean eradicating them because even though they are an invasive, non-native species, eradicating them may mean harming our native ant populations in the process. We need to find a responsible balance.

I am not sure we can reach a compromise with the Rasberry/Tawny Crazy Ant.  While they do not “sting” like the RIFA, they can bite.  They are not as much of a safety threat as the RIFA, but they are an economic threat, on several levels.

RIFAs are easily controlled with an organic program.  The Rasberry/Tawny Crazy Ant is more of a challenge, but it can be done with persistence and determination.

Interesting reading: