Utah Pests News Summer 2009

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Erin Hodgson accepted a once-in-a-lifetime position as Extension Entomologist in soybeans at Iowa State University. In her short time at USU, she touched many lives and was extremely productive, bolstering the UTAH PESTS program with fact sheets, research, educational tools, and energy. Her laughter and good spirits will be greatly missed.


Diane Alston 
Entomology Specialist  

Ryan Davis
Insect Diagnostician 

Marion Murray
IPM Project Leader 
Editor, Utah Pests News

Utah Plant Pest Diagnostic Lab
BNR Room 203
Utah State University
5305 Old Main Hill
Logan, UT 84322

Utah Pests News is published quarterly by the UTAH PESTS staff. 





Additional articles in this issue:

USU Joins School IPM Work Group

All Utah Counties Now “Scoped”

Curly Top Virus Beginning to Show up in Southern Utah

The Right Trap for the Right Wasp

Natural Control for Invasive Wasp

Black Grass Bug Explosion in Utah Rangelands

Disease Spotlight: Armillaria Root Rot

News, Publications, Web sites


Pavement Ants Forming Colonies Now

The pavement ant (Tetramorium caespitum: Formicidae) is one of Utah’s most frequently encountered home-invading ants.  This species, which derives its name from its habit of nesting below patios, driveways, and sidewalks, forms colonies of up to 4000 members.  They have a voracious and varied appetite of proteinaceous foods like grease, fat, insects, and sugary foods such as honeydew, fruit, and sweets. 

Like termites and some members of the bee, wasp, and ant family (Hymenoptera), pavement ants are highly social insects.  Sociality in ants includes a queen, multiple generations of worker ants, male reproductive ants, and sharing of responsibilities in the colony by all castes.   Most importantly, the ant social system is dependant upon food sharing (trophallaxis), and the transfer of nutrients through bodily secretions from workers to reproductives (queens and males) and larvae, and from larvae to workers and reproductives.  Pavement ant workers are 3/16-inch long and may have one to multiple queens. 

Ants have a complete life cycle consisting of an egg, larva, pupa, and adult. In spring (or whenever conditions are right), homeowners can see pavement ants swarming, when winged males and queens leave the nest and congregate to mate.  Newly mated queens will search for new nesting locations, which may occur inside or outside the home.  Winged, swarming ants are often mistaken for termites. 

Pavement ants generally colonize areas under concrete, logs, or rocks, or may even nest in the open on exposed soil.  Outside, these ants are harmless, but can become problematic when they enter buildings in search of food.  Occasionally, they will nest in wall voids and behind baseboards.  Pavement ants form long, distinct trails of worker ants, which can be seen up to 30 feet away from the nest.

Top: Pavement ants enter into battles that can leave hundreds dead.  Bottom: Lateral view of adult pavement ant. Note the spine-like projections and the double node.

Multiple tactics should be used to eliminate ant colonies and exclude ants from your home:

  1. Locate nests and entry ways into the house.  Observe ant activity and follow ant trails back to their source. Ant trails may be along baseboards, under carpets, or along plumbing or electrical pathways.
  2. Use some or all of the tactics listed below to suppress pavement ants.  The more tactics you use, the more likely you will see results.
    • Caulk all cracks and crevices where ants may nest or enter.
    • Vacuum regularly and clean up all crumbs and spills.
    • Keep human and pet food properly stored in air-tight containers.
    • Remove large rocks, boards, lawn ornaments, etc., under which ants may colonize.
    • Prune plants from contacting the house.
    • Keep ants from entering trees by using a sticky band around the trunk.
    • Create a dry, plant-free gravel border around the foundation.  Wood mulch provides habitat for ants to construct nests.
    • Control honeydew-producing insects like aphids and soft scales.
    • Sponge invading ants and ant trails with soapy water.
    • Drench each individual ant mound with an insecticide.
    • If ant nests are inside the house, wall void and baseboard treatments may be needed.  Use in conjunction with other tactics to prevent re-infestation.
    • Deploy bait stations (boric acid, fipronil, hydramethylnon, etc.).

  Worker ants are distinguished from others in the colony by the rough grooves found on their head and body, which may be seen with a 30x hand lens.
Spraying worker ants outside the nests will not suppress pavement ants. The queen must be killed to successfully eliminate an ant nest. Ant baits are designed to target the queen.  Worker ants take the chemical back to the nest and share it with other nest mates and the queen(s).

Because of their diverse diet, multiple types of baits should be placed along ant trails to test which one the ants most prefer.  Select their favorite baits and place them outside the home near the point of entry. Check baits frequently and replace dried or spent units.  Always place baits where children and pets cannot access them.  Ant baits may only be partially effective at controlling pavement ants given their diverse eating habits, and should be used in conjunction with other methods for increased control.

Goals for controlling pavement ants should be long-, not short-term.  Because ants are small, diverse, and vary greatly in their biology, it is recommended that all ants should be identified before considering a control program.  Samples may be sent to the Utah Plant Pest Diagnostic Lab for proper identification and a timely response with control recommendations.

-Ryan Davis, Arthropod Diagnostician


Featured Picture of the Quarter

Each female lady beetle may lay from 20 to 1,000 eggs in her lifetime, often in small clusters in protected sites.  If predator food is not readily available, lady beetles will eat eggs within and between beetle species.

Lady beetles are highly effective predators, especially against aphids.  They are most effective when aphid populations are high.  The convergent lady beetle adult can consume up to 50 aphids per day, and the sevenspotted lady beetle adults can consume several hundred aphids per day.

-Photo by Marion Murray