House and House-infesting Landscape Pests and their management Bastiaan M. Drees and Bill Summerlin*

Winged ants Winged s a group, ants are the most difficult house- ■ Hind pair of ■ Both pairs of wings hold pests to control. In some cases, treat- wings shorter have same size and ment methods such as spraying than front shape Aonly make the problem worse! Learning to iden- ■ ■ tify ants, understanding their and Elbowed antennae Hairlike antennae knowing control alternatives will help make ■ Narrow “waist” ■ No narrow “waist” combating them a success. between and thorax Behavior The presence of winged ants outside, such as around porch lights, should not be a concern, Ants are social . Their or colonies although in high numbers they can be a nui- can be found indoors and out, although some sance. Most winged forms are unsuccessful in have preferred nesting sites. A con- establishing a new . Turn off porch lights tains one or more queen ants laying and or use yellow “bug” lights to make these loca- being cared for by worker ants. Worker ants— tions less attractive to them. sterile or non-reproductive female ants—tend the queen and brood (eggs, larvae and pupae) and Ants form new colonies in several ways. Most forage for food. Foraging ants can invade house- are started by a newly mated winged reproduc- holds from colonies outdoors. tive, now called the . After finding a suitable nesting site, the queen loses her wings Nests often can be located by following “trails” and begins laying eggs, which hatch into legless, of foraging ants. Indoors, ants nest almost any- grub-like larvae. The queen feeds the larvae as where. For instance, Pharaoh ants readily nest in they develop through several stages in which attics, appliances, linens, heating ducts, wall they molt and grow between each stage. After- voids and light switches or fixtures. Killing forag- ward, they form pupae and soon emerge as adult ing ants rarely solves an ant problem in . Once worker ants have developed, the home because the colony remains unaffected. queen no longer needs to care for the brood. During certain times of the , most species Some ant colonies have more than one queen, produce reproductives, winged male and female and mating may occur within the nest without ants that leave the nest to mate and establish . These ants form new colonies when new colonies. When winged ants swarm in the one or more queen ants, along with some work- home, their colony is likely to be located some- ers and brood, leave the nest and move to a new where inside. Winged ants can be distinguished location. Ant colonies do not nest in permanent from termites by three characteristics (also see locations; frequently entire colonies move from Extension publications L-1781, Subterranean one nesting site to another almost overnight. Termites and L-1782, Drywood Termites): Particularly during very wet or abnormally hot and dry weather, ant colonies whose nesting * Professor and Extension Entomologist; Technician II; The Texas areas are flooded or lack food and water often A&M University System migrate indoors.

Texas Agricultural Extension Service ¥ Zerle L Carpenter Director ¥ The Texas A&M University System ¥ College Station Texas Worker ants foraging for food and water fatty foods (pies, butter, liver and bacon). Nests become a concern when they infest food or other are found rarely outdoors and almost anywhere items in the home. Although most ants consume indoors (light sockets, potted , wall voids, a wide variety of foods (they are omnivorous), attics, in any cracks and crevices), particularly certain species prefer some types of foods and close to sources of warmth and water. some even change their preferences over time cycle: Complete . A work- (Table 1). Species of ants that sting, such as red er ant develops from an (5 to 6 days) through imported fire ants, can endanger young children, several larval stages (22 to 24 days), a prepupal confined pets and bedridden people. stage (2 to 3 days), a pupal stage (9 to 12 days) Foraging workers of some ants establish tem- to an adult ant. Development from egg to adult porary chemical () trails that help takes from 38 to 45 days (4 days longer for sexu- other ants find food and water. These species can al forms). “recruit” other ants to a resource quickly and in Colonies consist of one to several hundred high numbers. Food is brought back to the queen ants, sterile female worker ants, periodi- colony and fed communal- cally produced winged ly among the male and other members female of the colony, reproductive including the ants (sexu- queen(s) and als) and brood, a brood process called (develop- . mental For some stages). species, such Red imported fire ants These ants as Pharaoh do not ants, larvae are swarm. Colonies multiply an essential part of the by “budding,” in which a food chain because they large part of an existing digest food brought by colony migrates carrying worker ants and regurgi- brood to a new nesting tate it for the rest of the site. colony to consume. Without larvae, the colony Red imported fire would starve. Most adult ant, Solenopsis invicta ants cannot ingest solid Carpenter ants food particles. Red imported fire ants infest the eastern two-thirds of Texas. They build hills or mounds in open areas where the colonies live, Common indoor ant species although colonies occasionally occur indoors and in such structures as utility housings and Several ant species are common household trunks. When a mound is disturbed, worker ants pests in Texas, with Pharaoh ants, fire ants and mount a rapid defense, quickly running up verti- carpenter ants topping the list: cal surfaces. Pharaoh ant, pharaonis Worker ants range from 1/16 to 3/16 inch (1.5 to 5 mm) long and are dark brown. Queen ants This is the most commonly occurring indoor 3 ant in Texas. Also called “sugar ants” or “piss are larger ( /8 inch) and lose their wings after ants,” these are some of the smallest ants, about mating. 1/12 to 1/16 inch long, with light tan to reddish Sterile female workers can sting bodies. In hospitals, they have been suspected repeatedly. First they bite; then, while holding to be carriers of more than a dozen pathogenic onto the skin with their jaws, they inject bacteria including Staphylococcus, Salmonella, with at the end of their . The Pseudomonas and Clostridium. These ants do not unique venom produces a fire-like burning sen- sting and usually do not bite. sation. Most people react by developing a Pharaoh ants are omnivorous, feeding on whitish pustule or fluid-filled blister at the sting sweets (jelly, particularly mint apple jelly, sugar, site after a day or two. Those hypersensitive to , etc.), cakes and breads, and greasy or the stings should be prepared for a medical emergency if stung. Most people can tolerate four stages (instars) before pupating. Develop- multiple stings, but may have problems with sec- ment requires 22 to 37 days, depending on tem- ondary infections at the sting sites. perature. Fire ants are social insects, with each Fire ants are considered to be medically colony containing one or more queen ants. important pests of people, pets, livestock and Queen ants can produce about 800 eggs per day. wildlife. Although omnivorous, fire ants primari- A “mature” colony can contain more than ly eat insects and other . Their 200,000 ants along with the developmental and predatory activities suppress populations of adult stages of winged black-colored male and ticks, chiggers, and other insects. reddish-brown female reproductives. These ants stay in the colony until conditions exist for their Life cycle: Complete metamorphosis. Eggs . hatch in eight to 10 days; larvae develop through

Ant Characteristics Table 1. Characteristics of common house-infesting ants of Texas. Foods Workers’ Length of Preferred preferred Swarming ability to Follow workers Species nest location indoors season sting bite trails (inches) Nest location: primarily indoors Pharaoh ants in scattered grease, meats, none No No Yes 1/16 locations near sweets heat and moisture sources Nest location: usually nest outdoors, but can be found in or on buildings Red imported lawns, gardens, meat, greases all year Yes Yes Yes/No 1/8 to 1/4 fire ants beds Carpenter ants usually in stumps sweets and May to late No Yes Yes/No 1/4 to 1/2 and logs; also in nearly anything July homes and fences else Thief ants nests of other grease in cheese late July to No No No 1/16 ants, , cracks and meat, September in wall sweets Odorous under stones or sweets, meat, seldom No No Yes 1/8 house ants boards in walls or dairy products under floors Acrobat ants protected galleries slight prefer- early summer No* Yes Yes/No 1/8 to 1/4 in mortar and ence for sweets to early fall wood and meats Nest location: generally nest only in soil, outdoors Argentine ants lawns, plant beds, sweets, rare, April, No No Yes 1/16 to 1/8 litter, trash fat May piles Crazy ants trash piles, tree sweets, meat spring No No Yes 1/16 to 1/8 cavities, rotten grease, fruit wood, soil Little black lawns, under grease, sweets, May to No No Yes 1/16 ants objects, rotten meat, fruits September wood and vegetables Tramp ants cracks in or near grease, meat May to June No No Yes 1/8 sidewalks, honey pavement Pyramid ants gardens and plant sweets June to August No No Yes 1/8 beds * have non-functional Carpenter ants, Camponotus sp. nests are excavated and usually also contain Fourteen species of carpenter ants live in parts of dead colony members. Texas. The largest, the black , Life cycle: Eggs develop from egg to worker Camponotus pennsylvanicus, is found primarily ant in about two months. Carpenter ants are outdoors in wooded areas. Common indoor social insects, living in colonies made of different species, Camponotus rasilis and C. sayi, have forms or “castes” of ants. Mature colonies con- workers with dull red bodies and black tain winged male and female forms (reproduc- abdomens. Worker ants range from 1/4 to 1/2 inch tives), sterile female workers of various sizes, long. They can be distinguished from most other and a wingless 9/16-inch-long queen. Winged large ant species by the top of the thorax, which forms swarm during May through late July. The is evenly convex and no spines. Also, the presence of 3/4-inch-long winged forms in the attachment (pedicel) between the thorax and home indicates that a colony is living indoors. abdomen has but a single flattened segment. Other ant species occasionally encountered in Although these ants bite, they do not sting. and around the home include: Foraging worker ants in the home can be a ■ Acrobat ants, nuisance. Carpenter ants usually nest in dead sp., wood, either outdoors in which nest under old stumps and dead parts stones, in stumps or of and around dead wood, and homes (in fences, occasionally invade firewood, etc.) or the home. Some indoors (between species make carton wood shingles, in nests in trees. These siding, beams, ants often hold their joists, fascia boards, heart-shaped etc.). Ant colonies abdomen up over are often located in their bodies. They cracks and crevices Acrobat ants Big-headed ant feed primarily on between structural produced timbers, but the ants can by . also tunnel into structural wood to form nesting gal- ■ Argentine ants, leries, although this is less humilus, common in Texas. They whose workers are light seem to prefer moist, to dark brown and gen- decaying wood, wood with erally nest outdoors. dry rot or old gal- They are uncommon in leries. However, damage is areas infested by fire often limited because these Crazy ant ants. ants tunnel into wood only to form ■ Bigheaded ants, nests and do not eat wood. Galleries excavated in species, whose major worker ants have relatively wood to produce nesting sites can weaken struc- large heads compared to their bodies. They have tures. 12-segmented antennae with a three-segmented Occasionally carpenter ants, particularly club. Similar in habits to fire ants, they feed on Camponotus rasilis, nest under stones or in other live and dead insects, and honeydew out- non-wood cracks and crevices. Foraging worker doors and greasy food sources and sweets ants leave the nest and seek sweets and other indoors. foods such as decaying fruit, insects and sweet ■ Crazy ants, longicornis, whose exudates from aphids or other sucking insects. fast-running, grayish-black worker ants have long Nesting tunnels when produced by carpenter legs and antennae. Although they nest primarily ants usually follow the grain of the wood and outdoors, they will forage in homes. They are around the annual rings. Tunnel walls are clean omnivorous, but difficult to attract to ant baits. and smooth. Nests can be located by searching ■ Little black ants, Monomorium minimum, for piles of sawdust-like wood scrapings (frass) small, slow-moving, shiny black ants. Workers under exit holes. These piles accumulate as the prey on insects and feed on honeydew produced by sucking types of insects such as aphids. ■ Odorous house ants, sessile, they kill only a few workers and often do not which look somewhat like fire ants, but when greatly affect the colony, the source of workers. crushed have a pungent “rotten-coconut-like” Using surface applications on ant trails actually smell. can make Pharaoh ant colonies divide and make ■ Tramp ants, species (e.g., T. the infestation worse! When home control bicarinatum), whose workers also resemble fire attempts fail, seek help from a licensed commer- ants. However, close examination reveals that the cial pest control operator. head and thorax are roughened with parallel Appropriate control methods vary with the ant grooves rather than smooth. species and nature and locations of infestation ■ Ghost ants, , also (also see Extension publications, L-1783, becoming a problem in Texas. Carpenter Ants, and B-6043, Managing Red Imported Fire Ants in Urban Areas). Other house- infesting ants can be controlled through the gen- How to manage ants eral methods discussed below Ant problems occur in with prod- homes and structures pri- ucts containing ingredi- marily because food, water ents listed in Table 2. and favorable nesting sites Finding and treating are available there. ant nests: To locate ant Meticulous housekeeping nests, investigate move- eliminates significant ant ment patterns. Worker problems by removing ants will often lead you needed resources. back to the nest. Furthermore, ant Another bait treatments good tech- are more effec- nique is to tive if alternative use small food sources for bait stations the ants are to trick the eliminated as ants into much as possi- revealing ble. their nest Odorous house ant Most ants pre- Tramp ant locations. fer to nest in soil Use soft- or wood outdoors, but drink or pill-bottle caps homes offer many favorable nest sites for certain baited with small ants. Cracks and holes in brick veneer, wall amounts of peanut butter, mint apple jelly, bacon voids and structural wood close to heat and grease or other attractive materials. One or more moisture sources are commonly used. Reduce of these foods will attract the ants. Watch them water sources and nesting sites by caulking as they locate the food and take some of it back cracks and crevices, fixing leaks and replacing to the nest. They may even establish an odor wet or rotten wood. Pay particular attention to for other workers to use to find the food, so ant colonies infesting potted plants or fire wood an ant column may develop. brought indoors. Although these steps take time and effort, they registered for ant control are for- eliminate undirected, ineffective insecticide mulated as liquid sprays, dusts, fogs and baits. spraying indoors and make ant elimination by Many are generally labeled to control “ants,” nest treatment quick and efficient. Also, remem- although some are specifically registered for par- ber which food item(s) the ants prefer and where ticular ant species. ants were attracted. Knowing this allows you to make a more effective ant bait and place it The most effective ant control is to find the where ants are most active. nest and treat it with insecticide. An alternative is to use the workers to carry an insecticidal bait Treat indoor nests with an insecticide regis- back to other colony members. In the home, tered for this use. Dust formulations are pre- extensive, undirected insecticide treatments, ferred for treating nests indoors because they do such as ant trail treatments or total-release not stain and generally give longer residual con- aerosol fogs, are usually unsatisfactory because trol than sprays. Apply dusts sparingly in thin, Insecticides for Ants Table 2. Insecticides registered for control of ants in and around the home (Note: Some prod- ucts have mixtures of listed ingredients, and some products are available only to licensed pest-control operators.) Ingredient Formulation(s) Use Indoors Outdoors acephate wettable powder, dust, surface application, perimeter x x aerosol barrier, mound treatment allethrin liquid, aerosol surface application, aerosol x x arsenic (arsenic bait bait station x x trioxide) abamectin B bait bait x x wettable powder, dust, surface application, perimeter x x granule barrier, mound treatment bifenthrin wettable powder, granule potting media treatment x borax (sodium liquid bait station x tetraborax decahydrate) bait, dust, aerosol bait, surface application, x x (orthoboric acid) perimeter barrier carbaryl liquid, wettable powder, surface application, perimeter x dust, granule barrier, mound treatment chlorpyrifos liquid, wettable powder, surface application, perimeter x x dust, granule, aerosol barrier, mound treatment, paint cyfluthrin liquid, wettable powder surface application, perimeter x barrier liquid, wettable powder surface application, perimeter x x barrier liquid, granule, aerosol, surface application, perimeter x x microencapsulated barrier, mound treatment dichlorvos controlled release electric box treatment esfenvalerate liquid surface application, perimeter x x barrier, mound treatment fenoxycarb bait bait x fenthion liquid surface treatment x fenvalerate liquid, aerosol surface application, perimeter x barrier fluvalinate liquid surface application x hydramethylnon bait bait, bait station x x isazophos liquid surface application x lambda-cyhalothrin wettable powder surface application, premise x x barrier malathion liquid surface application x permethrin liquid surface application, perimeter x x barrier, mound treatment oil, turpentine liquid mound treatment x propetamphos liquid surface treatment x propoxur liquid, wettable powder, surface application, perimeter x x dust, aerosol, bait barrier, bait station pyrethrins (many liquid, dust, aerosol surface application, perimeter x x contain piperonyl barrier, fog, mound treatment butoxide) Ingredient Formulation(s) Use Indoors Outdoors resmethrin liquid, aerosol surface application, perimeter x x barrier, mound treatment rotenone liquid, dust mound treatment x S-bioallethrin liquid surface application x silica dioxide dust surface application x (diatomaceous ) silica gel dust surface application x sulfonamide bait station bait station x sumithrin aerosol surface application, fog x tetramethrin aerosol surface application, mound x x treatment tralomethrin wettable powder surface application, perimeter x x barrier trichlorfon liquid, bait surface application, perimeter x x barrier, bait

even layers in the ant nest area. Professional Some bait formations for indoor use are avail- pest-control operators have equipment to drill able commercially: holes into colonies nesting in wood and wall ■ Abamectin baits, such as PT® 370, voids and for injecting insecticides directly into Ascend™ Fire Ant Stopper Bait, affect fire the nests. ants and “related ants.” Formulated similar Baits: If the nest cannot be found, use a bait- to Amdro® (see below). formulated product (below) or prepare a 1 (or 2) ■ Hydramethylnon baits include Combat®, percent boric acid bait using the following Superbait®, and MaxForce® Ant Killer Bait recipe: Stations for acrobat, Argentine, carpenter, ■ Choose the most attractive food material for crazy, fire, pavement, Pharaoh, thief and the ant species present, such as peanut but- odorous house ants. These formulations ter, mint apple jelly, corn syrup, etc. contain ground-up silkworm caterpillars and ■ Mix 1 part boric acid powder (available differ from Amdro® and Seige® formulations from most pharmacies) per 100 (or 50) parts (registered for outdoor use for fire, har- bait material, e.g., 1 teaspoon per vester and big-headed ants), in which the 2 (or 1) cups food material. same active ingredient is formulated in soy- bean oil coating defatted, processed corn Do not make the bait concentration of boric grit particles. acid too strong as this reduces its effectiveness. The 1 percent bait is better than higher concen- ■ Sulfonamide baits include Raid®, Max Ant trations because it is less repellent to ants and Bait and Johnson Wax Raid® Ant Baits Plus kills them as efficiently. Keep the bait fresh and for Argentine, cornfield, Pharaoh and black moist. Small amounts of bait can be placed in carpenter ants, and FluorGuard™ Ant bottle caps or on pieces of aluminum foil, or Control Baits for Argentine, cornfield, injected into short (2-inch-long) sections of soda Pharaoh and a “variety of household” ants. straws using a squeeze bottle. Place 20 to 30 ■ Sodium tetraborate (borax) and ortho small bait stations where ants have been seen or boric acid liquid or solid baits such as PIC were attracted to baits as described in the previ- Ant Control System are attractive to sweet- ous section. Do not place stations in areas acces- and grease- ants such as pavement, sible to small children or pets. If proper food is little black, black carpenter and odorous used and bait kept fresh, ants should be con- house ants. Drax Ant Kill Gel contains 5 trolled after three to four weeks. percent orthoboric acid in a mint jelly-based bait formulation for Pharaoh ant control. ■ Methoprene, an growth regulator, is Barrier treatments around the home: the active ingredient in Pharorid® for When ants nesting outdoors invade the home, it Pharaoh ant control. Queens fed this bait is often worthwhile to treat with an insecticide a fail to produce viable eggs and larval devel- 3- to 4-foot-wide bank or swath of soil around opment is terminated. the perimeter of the home and the lower 3 to 4 Effective bait formulations contain slow-acting feet of the house. If renewed at two- to three- that are collected by foraging worker week intervals while ants are active, this “barri- ants and brought back to the colony, where the er” treatment should greatly reduce or eliminate is fed to the other ants, queen(s) and ant invasion into the home. brood. These products should not be confused Granular insecticide formulations can be used with “bait traps,” which kill only the foraging instead of sprays to treat the soil. Water the workers attracted to the bait station. treated area lightly after applications to release Tips for using baits to control house-infesting the insecticide from the granules. Wettable pow- ants include: der formulations are generally more effective on brick veneer homes. ■ Use fresh product and follow directions carefully with the correct number of bait Treating around the home: Do not routinely stations or material to treat the infestation. treat the entire premises for ants unless the land- scape is infested with fire ants, or the ants con- ■ Make bait more effective by removing or tinually enter the home (see Extension publica- covering other food sources that compete tions B-6043, Managing Red Imported Fire Ants in with the bait’s attractiveness. Urban Areas or L-5070, The Two-Step Method Do- ■ Before and during baiting efforts, avoid It-Yourself Fire Ant Control). Ants are generally using surface applications of long-acting beneficial in our landscapes as they scavenge for contact insecticides (often applied to control food and prey on other potential pests such as or to ant trails) that would pre- various caterpillars and chinch bugs. Some - vent foraging worker ants from being able gathering ants, such as the red , to reach the bait station. Pogonymyrmex barbatus Smith, collect and feed ■ Be patient for the baits to work. It may take on weed seeds. three to four weeks or more to eliminate some colonies. Acknowledgments After ants have consumed the bait, apply The authors are grateful for the constructive dusts or other formulations to cracks, crevices comments and reviews from Jerry Cook, Harry and ant trails if necessary to kill surviving work- Howell and Dr. Pat Morrison. This is a revision er ants. of a manuscript originally written by John M. Owens (1983) and revised by Philip J. Hamman (1985).

The information given herein is for educational purposes only. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by the Texas Agricultural Extension Service or the Texas Agricultural Experiment Station is implied.

Educational programs of the Texas Agricultural Extension Service are open to all people without regard to race, color, , disability, religion, age or national origin. Issued in furtherance of Cooperative Extension Work in Agriculture and Home Economics, Acts of Congress of May 8, 1914, as amended, and June 30, 1914, in cooperation with the United States Department of Agriculture. Zerle L. Carpenter, Director, Texas Agricultural Extension Service, The Texas A&M University System. 5MÐ9-97, Revision ENT