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Help! I have a gigantic ant problem (millions of small black ants) in my garden. They are everywhere: in the flower beds, the veggie garden, the lawn, under the sidewalks and driveway. I have tried the sprays and spreadable pesticide from Lowe's, but nothing seems to work. They seem to multiply by the day, and are making work in the garden creepy and painful (they bite too). What can I do? There is no obvious food source around; except they seem to be eating the iris' roots. I live just above Orchard Drive and Bountiful High School. What can I do?

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Sounds like you have a lot of ants! Interestingly, I havethe same problem at home, but I choose to just let them go.  Ants, generally speaking, are difficult to eliminate. Spraying (using insecticides against) worker ants (all of the ones you see) with chemicals is ineffective in the overall fight against the ant colony.  Because ants can reproduce very quickly they can replace the worker ants almost as fast as you can spray them.

At the Utah Pest Plant Diagnostic Lab we believe (as do many others) that the control of any insect should begin with proper identification. Most people think that ants are just ants.  That is a very bad assumption; ants are one of the most diverse and abundant groups on the planet.  Different ants eat different things, have one, two or many sizes of workers.  They can have one to many queen ants, can reproduce colonies in various ways, and may or may not have mating flights one to multiple times in a year, and much more.

It is really important to know what your ants like to eat. In the nest, ants like to share food with each other. It is this sharing of food that can be used against an
ant colony. Ant baits are slow-acting insecticides that the ants eat, take back to the nest, and then feed to developing ants (larvae), etc.  If you are lucky the worker, or the larvae, will feed the queen ant(s) and you will have stopped the production of eggs. Over time the colony will go away.  This takes patience, however, and may not work if the particular ant species will not feed on the on the bait formulation you have selected, or if the queen ants are not affected.

So, you can try an all-purpose ant bait that you can purchase at your local garden store, or you can do it properly and send in a sample for me to identify.  If you do choose to use baits there are a couple things to keep in mind... 1) put the baits along ant trails (the long trails of ants that usually follow foundations, sidewalks etc.). Placing baits randomly in the middle of the yard won't get the job done. 2) Keep the baits away from small children. 3) Do NOT spray worker ants that are feeding on the baits.  They need to be alive to carry the chemical back to the nest.  This is slow acting material so you need to give it time. There are different formulations of baits: liquids, gels, granules and solids.  You can try using some or all of these at the same time. Baits can be found at your local garden center, or at a place such as Lowes.

Here are the addresses to our website, and directions to submitting a sample to the lab.  The more ants you can send, the better.  And make sure they are in some kind of liquid (rubbing alcohol or nail polish remover preferred).

UPPDL home page:          http://www.utahpests.usu.edu/
Submission Directions:    http://utahpests.usu.edu/uppdl/htm/forms

Given the widespread distribution of your ants it will be difficult to acheive complete control. It may take a couple years of baiting to eliminate all of the ants, and subsequent treatments to keep them out of your yard. I recommend getting these to a tolerable level in the areas you most frequent.

If you have more questions, please send me an email.

Posted on 23 Jun 2008

Ryan Davis
Arthropod Diagnostician, Utah Plant Pest Diagnostic Laboratory

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