Ants and Ant Control Dr. Richard M. Houseman Department of Entomology University of Missouri

Ants Order Hymenoptera –More than 8,800 species world- wide Social Insects –Division of labor Complete metamorphosis Complex Feeding –Feed on many different things –Circulate food within the colony

Social Organization Life Stages –Eggs Fertilized or unfertilized –Larvae Legless, grub-like stage Cannot feed themselves Perform no maintenance Digest solid materials –Pupae Inactive, pre-adult stage

Social Organization Life Stages –Worker Sterile adult females Most numerous stage in colony Responsible for all nest maintenance activities –Reproductives Queen = egg production; single or multiple queens King = winged; only for mating and dies afterward

Ant Biology Feeding and Nutrition –Eat many different kinds of food Honeydew, Sweets Protein, Oil Seeds, Plants Insects –Usually have preferred food types

Feeding and Nutrition Workers obtain solid and liquid food –Honeydew preferred –Aphids protected by many ants Trophollaxis –Solid foods digested by larvae –Digested food circulated through the colony by workers

Ant Biology Nesting Habits –Nesting sites usually chosen by instinct –Three Nest Types Soil nests Wood nests Opportunistic nests –Knowing nesting habits is important

Missouri Ants Hundreds of species –Not all considered pests. Several pest ants present Most belong to one of three groups –Myrmecinae –Formicinae –Dolichoderinae

Ant Management Identify the ant. Find out where the queen ant is living. Direct control measures at areas where the queen is living. Correct contributing conditions

Missouri’s Top Ten –Little black ant –Pharaoh ant* –Acrobat ant –Pavement ant –Carpenter ant* –Yellow ant –Cornfield ant –Allegheny Mound ant* –Odorous house ant* –Argentine ant

Pest Ant Identification Three Main Characters Antennae –All ants have elbowed antennae Waist –Pedicel with node(s) Anus –Nozzle or slit-like –With or without hairs

Pest Ant Identification Myrmecinae –Pedicel with two nodes Formicinae –Pedicel with one node –Anal hairs Dolichoderinae –Pedicel with one node –No anal hairs

Missouri Myrmecinae Little Black Ant –Opportunistic, budding Pharaoh Ant –Opportunistic, budding –Multiple, related queens –Supercolonies Acrobat Ant –Wood nests, single queen Pavement Ant –Soil nest, many queens together

Missouri Formicinae Carpenter Ant –Even thorax, multiple size workers, wood nests, single queen –Satellite colonies Yellow Ant –single queen; soil nest Cornfield Ant –single queen; soil nest Allegheny Mound Ant –Uneven thorax, Multiple size workers; soil nests; multiple queens

Allegheny Ant Mound (Formica exsectoides)

Myrmecinae Imported fire ant (Solenopsis invicta) –10S Antennae; 2S club –Honeydew, sweets, protein, oil, seeds, plants, insects –Workers multiple sizes –Single or multiple queens –Soil Nests Open, sunny areas; crater-shaped mound; under debris; inside logs; –Swarms spring through summer; colony budding

Missouri Dolichoderinae Odorous House Ant –Small; one size; opportunistic –Single queen; no swarm Argentine Ant –Small; one size; opportunistic –Multiple, related queens; no swarm

Ant Management Identify the ant. Find out where the queen ant is living. Direct control measures at areas where the queen is living. Correct contributing conditions

Ant Management Possible Control Tactics –Physical and Cultural –Chemical Directed at queen –Mound drenches –Void spaces –Wood treatments –Baits Directed at structure –Perimeter treatments

Ant Management Cultural –Sanitation Remove food sources Remove nesting sites –Debris piles –Vegetation Moisture control –Ventilation

Ant Management Physical –Exclusion Sealing cracks and crevices –Often very difficult due to size –Vacuuming Useful for removing exposed satellite colonies

Ant Management Chemical (Queen-directed) –Soil Drenches Soil-dwelling ants –Apply to mound, mulch, etc. Thorough penetration –Low-pressure spray –Watering can –Best for single queen ants

Ant Management Chemical (Queen-directed) –Void Treatments Wall voids –Nests usually found at base of wall Brick veneer –Apply at weep holes along outside Masonry brick/hollow blocks –Drill near infestation and inject insecticide –Dusts and aerosols commonly used

Ant Management Chemical (Queen-directed) –Wood treatment –Injection Drill into nest Dusts or aerosols

Ant Management Chemical (Queen-directed) –Baits Depend on species and colony (‘finicky eaters’) Sweet vs. protein feeders and yearly cycles –Try several different types until get good feeding –Placed near to the colony Use lots of bait in untreated areas In corners and along active trails Check within a week

Ant Management Chemical (Structure-directed) –Perimeter Treatments –Used to prevent workers from entering the structure Temporary relief Applied to base of foundation and area adjacent to foundation –Wettable powders, microencapsulated

Ant Summary Social Insects Different forms in colony; division of labor Many pest species in Missouri Unique in appearance and biology; identification is key to control Interesting Biology Communicate using chemical signals Food sharing within colony Variety of nesting habits and feeding preferences