Bugs, Bugs, Bugs-- June 2008
Ants appear to be the No. 1 problem at the moment, so here is some information on the ants we’ve had the most calls about in recent weeks.
1. Crazy raspberry ants — The exotic Texas ant, Paratrechina sp. near pubens, may be the Caribbean crazy ant. This ant has been known to short out many different types of electrical apparatuses, causing several thousand dollars in damage and remedial cost. It is also an annoyance to residences and businesses. These ants do not sting but can excrete chemicals for defense, or they may attack and will bite, but rarely. The ants are reddish brown about 1/8-inch in length and monomorphic. The body has numerous long, coarse hairs, and workers have long legs and antenna – though not as long as the crazy ant, P. longicornis. Their antenna is 12-segmented without a club, and they have a small circle of hairs at the tip of the abdomen (acidophore). They nest primarily out of doors but will forage inside. They nest under any structure or object that retains moisture. They are omnivorous and tend scales, aphids and other honeydew-producing insects in the Homoptera group. They also eat other insects and small vertebrates. Colonies are polygene (with multiple queens) and number in size from several hundred to a few thousand. Colonies do appear larger due to their unicolonial (supercolony) behavior. They have been found in enormous numbers, and colonies seem indistinguishable from one another. Foraging trails are quite apparent, and individuals forage erratically – hence the reference to crazy ant. No mating flights have been observed in the field despite winged reproductives. This may indicate the species propagates by budding, with breeding occurring at or near the edge of the nest, creating new colonies at the periphery, thus producing the supercolonies. They have been found in Texas since 2002 in several locations in the area around southeast Houston. Typical management tactics for other ants do not provide adequate control of these ants. They are not attracted to baits. Available treatments only provide temporary “buffer zones” for about two to three months. But these materials are not available to the homeowner. Contact your pest control provider if you think you have a problem with these ants. Figure 1. Information courtesy of Texas A&M Extension.
2. Crazy ants, Paratrechina longicornis – An introduced species from Africa or the Orient, it has become widely distributed by commerce to many parts of the world. It is well-established in many towns and cities of the Gulf Coast region, especially Florida. Further north it is more sporadically distributed, being found in buildings, hotels and greenhouses. It gets its name from the workers’ habit of darting about in a jerky manner, lacking a sense of direction. Like is relative above, it has a long, 12 -segmented antenna without a club, and it has longer legs. The body has long, scattered, grayish to whitish hairs. The body is dark brown to black with bluish reflections. Workers move very rapidly and have been even known to jump, according to observers. They apparently have a good sense of smell and find foods very quickly. This is a highly adaptable species and can be found in dry to moist habitats nesting in such places as trash, refuse, cavities of plants and trees, rotten wood and soil under objects. Colonies are moderate sized to large. Worker are omnivorous, feeding on both live and dead insects, seeds, fruit plant exudates and many household foods as well as honeydew from other insects. Use a liquid contact spray as a barrier to prevent entrance into structures. Sweet liquid baits have been known to work.
Figure 2.
3. The Texas town or leaf-cutting ant, Atta texana — Known by several other local names, these ants infest parts of eastern Texas and western Louisiana and occur in northeastern Mexico. The body of these ants is a dark- to rusty-brown color with long legs. Its antenna is 11-segmented without a distinct club. They have large mandible with several teeth used to cut foliage and bite – occasionally drawing blood – particularly by the large guard ants. The dorsum and head bear prominent spines – two pair on the head and three on the thorax. Nests are in the soil and are constructed on well-drained sandy or loamy soils. The interior of the nest may go down in the soil 20 feet or more and contain numerous chambers interconnected by tunnels. Within many of these chambers the ants cultivate a fungus on a substrate of macerated leaves. This is the primary food source for the ants and the brood. The colonies have three castes – the minor workers cultivate the fungus and care for the brood, the medium-sized workers cut and gather the leaf material back to the nest and the major workers guard the nest. The surface of the nest hills have numerous holes surrounded by crescent or crater-like piles of soil. The tunnels that lead to these opening on the surface are used to ventilate and regulate the interior temperature and moisture of the colony and as passageways for the leaves to be brought in. A very large nest may occupy 4,500 square feet at the central portion of the nest, and entrances for a single mound may be found over an acre. Some colonies are very old – the same colony occupying the same nest for 60 to 70 years. Foraging may occur 300 to 600 feet from the colony with very noticeable trails with ants moving back and forth carrying pieces of foliage as well as flowers removed from neighboring plants. Most of the foraging is done at night during the warmer times and during the day in the cooler periods. The ants cut foliage from almost any plant. They will also transport caterpillar droppings, Spanish moss, seeds of juniper and hackberry, corn, cornmeal, flour, rice, coffee grounds and many other materials. Nuptial flights take place in April and June with thousands of winged reproductives emerging from the colony over a period of weeks. These flights usually occur on bright, still, moonless nights just before dawn. A colony may have as many as five queens and several hundred thousand ants. Damage from the colonies is manyfold, from invading homes and stealing food to stripping foliage from trees, shrubs and gardens, building unsightly nests and tunneling under and collapsing roads, walks, or homes. Management was once obtained using methyl bromide injected into the tunnels, but this has been discontinued. Two baits were on the market – Volcano and Blitz – but have since been removed and sent to South America where the leaf-cutting ants are a greater problem. Presently we have only Amdro Yard Guard, and only insecticides that have ants on the label. Some control has been provided with Orthene in past demonstrations. But several products that have just a general label for ants are available. Figure 3.
4. Pharaoh ants, Monomorium pharaonis — An introduced species from the African region has been widely distributed to all parts of the world by commerce. It is one of the best-known and most common of all house infesting ants. They occur in every town or city of commercial importance in the United States. Though not widely or uniformly distributed, it is especially common in hotels, large apartment houses, groceries or other places where food is commercially handled. Workers are monomorphic (one size) with erect hairs that are sparse on the body. Head and thorax are densely but weakly punctulate, giving it a dull appearance. The abdomen is shiny, and body color ranges from yellow or light brown to reddish. It normally nests in inaccessible places in buildings and breeds year around. In houses they can nest between sheets of stationary and layers of linens and in other unusual places. They feed on jelly, sugar, syrup and other sweets, cakes, breads, pies, butter, liver and bacon. They prefer grease, fats and meats. Workers will feed on both live and dead insects. Pharaoh ants are without doubt the most persistent and difficult of all house ants to control. They have multiple-queen colonies, breed year around, have access to unlimited food supplies and do not have to expose themselves to the elements or enemies to find suitable nesting sites. All these enhance their ability to be successful. Additional colonies are formed by splitting or budding from the mother colony. They can be confused with some species of fire ants. Management of these ants is by bait only because sprays tend to induce the colonies split, making them worse. Figure 4.
5. Argentine ant, Linepithyema humile — A native of Brazil and Argentina, they were widely distribute by commerce. Initially brought to New Orleans on coffee ships before 1891, they rapidly spread over the Southeast except Kentucky and Virginia. They also are widely distributed in California. Infestations occur in several large cities like Chicago and St. Louis. The antenna is 12-segmented without a club; the body has few sparse hairs absent from the thorax. Body color is a uniform light brown to brown. Workers emit a stale, greasy or musty odor when crushed. This ant’s success as a competitive species is attributed to its ability to nest in diverse habitats, produce large numbers of individuals from multiple queens, thrive on a wide variety of foods, live in a friendly intercolony basis with its own species and exterminate other species of ants. They and the Southern fire ant are arch enemies because they compete for food and habitat. Argentines will nest in exposed soil, soil under cover and in rotten wood, faulty places in trees, refuse piles, bird nests, bee hives and many other places. New colonies apparently are formed by one or more females migrating from the mother nest accompanied by a group of workers. Workers are predaceous, carnivorous and grainivours. They feed on excretions from Homopteran insects and on secretions from floral and extrafloral parts of plants, and they gnaw into buds on fruit trees such as citrus and fig. The number of ants in a well-established area is immeasurable. The active workers get into every conceivable place, both indoors and out. They exterminate all native ant species and become the dominate form in an area they infest. Large numbers can be seen running up and down trees foraging. Although common in urban and city areas, they can become easily established in rural areas. They are the most persistent and troublesome of house-infesting ants. Native ants will come and go, but infestations of Argentines are persistent and continuous once they become established in an area. They will feed on just about everything with a preference for sweets. Their habit of crawling everywhere – especially over refuse, filth, feces, carrion or sewage – affords them the opportunity to transport organisms of dysentery and tuberculosis. Management is best with baits. Mix 8 teaspoons of sugar and 1 teaspoon of boric acid in a pint of warm water and mix. Using a small glass jar (such as a baby food jar) place several cotton balls in the bottom of jar and then saturate the balls with the solution. Place the lid on and punch several small holes just large enough for the ants to enter. Then set it in a place where ants are traveling. Periodically replenish solution after dumping out the dead ants. Be patient because it takes a while to reduce the populations. Outside use granular baits and contact insecticides to suppress large colonies and as a barrier to food sources for ant control. Figure 5.
6. Carpenter ants, Camponotus sp. — These are very large scavenger-type ants that usually nest in water-soaked or decaying wood. There are several species with variable color both within the species and between species. They have a 12-segmented antenna with no club. They do not sting but can emit formic acid. They are a polymorphic species with variable sizes, but overall they are large and robust. Nests are most commonly found in living trees with heart rot or dead trees or stumps. They may occasionally be found in the hive bodies of bee colonies where the wood has been water-soaked and begins to rot. Nests consist of 1,000 workers, which forage at night. They feed on honeydew from scales, aphids and whiteflies as well as fruits and some insects. Reproductive flights occur during the summer months. Exhibits of carpenter ant nests can be set in large aquariums with large plastic tubing running to various feeding stations. Carpenter ants usually get indoors from tree branches touching the roof or walls of houses, using them as pathways to scavenge. Remove all branches that touch the house as a good preventative control. Follow ants back to the nest site to treat the nest area for best control. Many insecticides are available for ant control, and some bait are made specifically for carpenter ants. Figure 6.
7. Spider mites – Hot, dry weather has caused an explosion of spider mites on citrus and vegetables and several ornamentals like roses. The webbing and the stippling of the foliage and dulling of the fruit are typical signs of an infestation. Miticides will help in each of these areas for control. The use of Ultra fine oils or paraffinic oils can be used alone or with a miticide to manage these populations. Be sure to keep grass and weeds near these commodities cut and sanitize the areas. Initial infestations come from nearby weeds, and their management can reduce these infestations. Remember you are watering these plants and keeping them succulent. The drought has dried up most of the plants they normally feed on, so the mites migrate to the better food source. Figure 7.
8. Fall web worms — Those large, silky webs in the trees are cause by the immature of this pest. The caterpillars are voracious feeders and “web up” the branches to protect themselves from predators, parasites and sprays. There are two color phases – a light one and a dark one – and both are extremely damaging. Do not try to burn them out because you may get your house or the neighbor’s as well. Sprays using a hose-end sprayer and a little pyrethroid and a little soap will do an excellent job. Make the application in the late afternoon and wet the foliage around the webbed area as well. The hose-end sprayer will throw a stream about 30 feet into the tree, so wet the entire nest and the foliage around it. This foliage is what the caterpillars will web up tonight to eat tomorrow. Early treatments will reduce the area populations so you will have fewer problems with this pest. Web worms can have a generation every 30 days, so treat as necessary. Figure 8.
9. River birch sawfly — These light green caterpillar-like worms are actually hymenopterans larva. They look like caterpillars but are quite different. They have one simple eye on each side of the head and a pair of legs on each segment of the abdomen. (Caterpillars have a series of simple eyes on each side of the head and from one to 4 pair of abdominal legs.) The sawflies feed like caterpillars, eating the foliage of the host plants and defecating on the ground beneath the plants – sometimes covering the ground. They are particularly annoying when there is a picnic table under the infested trees. They can be controlled just like caterpillars, either with sprays or with systemics applied around the drip lines of the trees. Figure 9.
10. Citrus psyllid — This pest is a new invasive that recently was found on citrus in the state. To date the infestation is found only in Jefferson and Orleans parishes. This pest has the potential to spread citrus greening disease. To date we have not found the disease. Inspections are being made to check the distribution of the psyllid and to check trees for the disease. The Louisiana Department of Agriculture and Forestry is working with APHIS and USDA to survey the citrus areas to determine the extent of the infestation and if the citrus greening disease is present. This is not the first pest we have found in the state that has the potential to spread a disease, but to date we only have the insects. Recommendations are being gathered to use in both the commercial and homeowner areas to control this pest. For additional information check the citrus section on the LSU AgCenter Web site for further details and recommendations. Figure 10.
Until July,
Dale
| | Figure 1. Exotic ant or crazy raspberry ants of Texas. Report any suspected findings. |
| | Figure 2. Crazy ants. Note long legs and antennae. |
| | figure 3. Texas town or leaf-cutting ants and distribution. |
| | | Figure 6. Carpenter ants and injury. |
| | Figure 7. Spider mites and their webbing and injury. |
| | Figure 8. Fall web worm damage to tree foliage. |
| | Figure 9. River birch sawfly larvae. |
| | Figure 10. New invasive -- the citrus psyllid. |
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