Ants Galore

As we have said before, ants are beneficial for the ecological services they provide (soil aeration, predation, seed dispersal, etc.).  However, there are times and places that ants are not welcome, and this is another spring with many calls and inquiries about unwanted and unloved ants and ant mounds.  It seems that warm soils and recent moisture have kicked ant colonies into overdrive.  Now is also the time of year that ant mounds become most noticeable.

Field ants can be brown or black, but all have a notch across the top of the thorax
Field ant worker

The ants that nest in the ground are called field ants.  Many of these are “the other” big black ants.  The public often assumes that “big black ants” are carpenter ants.  However, carpenter ants do not nest in the soil.  Instead, they nest in moist, decayed wood such as hollow trees and rotted window sills.  Not all field ants are large and black; there are many small, lighter-colored field ants as well. 

We should be able to tolerate ant mounds in the lawn and garden, up to a point. That point is reached when the ant mounds grow taller than the grass. There is the possibility that ant mounds will smother the grass, or in my case, create an “unevenness” in the flatness of the backyard.  Ant mounds will dull mower blades as the blades cut through the deposited soil.

We should tolerate ant mounds in the lawn if you can. Try to rake or water down mounds that appear to be getting too tall.  Finally, sprinkle insecticide on just the mound if treatment feels warranted. My experience is the mound treatment does not eliminate the colony; it just slows them down.

The other time ants seem problematic is when a colony digs and tunnels around vegetable transplants.  Ants do not feed on the plant roots, but they may excavate so much soil from next to the plant that the roots are exposed to air and dry out, thus stunting or killing the transplant.  If ants threaten your transplants and the plant is still healthy enough to recover, you can drench the soil around the transplant with a garden insecticide solution.  There is no need to treat the entire garden.

More articles about ants in the lawn, garden, and pastures:

Field ants have a notched, uneven thorax, carpenter ants have an evenly rounded thorax

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