Biting Flies, Grasshoppers and Fire Ants
Are outdoor flies biting you?
Have you ever wondered what types of flies, other than mosquitoes, can bite when you are outside? Well, there are plenty of other biting flies, including deer flies, horse flies, stable flies, black flies, biting midges and sand flies. All biting flies locate humans and other animals by sensing things in the environment -- carbon dioxide, dark colors, movement, warmth and perspiration. Once a host is located, a biting fly inserts its piercing mouthparts and injects its saliva with anticoagulants to keep the blood flowing. In sensitive individuals, the fly’s saliva can cause life-threatening allergic reactions. In addition, some flies can transmit disease.
Deer flies are about ¼-inch in length and are typically yellow-brown to black in color with dark bands on their wings. The larvae of deer flies are aquatic, so the adult flies are usually found around streams, lakes, ponds, marshes and swamps. The adult flies have scissors-like mouthparts that cut into skin, causing blood flow, which they lap up. Deer flies (Chrysops discalis) can transmit tularemia, which is a bacterial disease.
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A deer fly, Chrysops sp. (Diptera: Tabanidae), adult female. Photo by Bart Drees, professor and Extension entomologist, Texas A&M University.
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Horse flies are more than 1 inch in length and black or light brown in color, with shiny green eyes. They are strong, fast fliers and use their scissors-like mouthparts to cut into skin. The larvae of horse flies usually live in water or in moist locations, where they prey on other insects. As the larvae grow and then pupate, they move to dryer soils.
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A horse fly, Tabanus sp. (Diptera: Tabanidae), adult female. Photo by Bart Drees, professor and Extension entomologist, Texas A&M University.
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Stable flies are ¼-inch in length, and gray in color with four dark stripes on the thorax. This fly has pointed mouthparts that it uses to suck blood, causing a sharp pain when it bites. Stable flies lay their eggs in piles of decaying vegetable matter, such as haystacks, grass clippings and manure.
Black flies are around ¨û inch in length with broad wings and a hump-backed appearance. They prefer wet environments, so they are found near ponds, creeks and rivers. Even though black flies do not transmit disease to humans in the U.S, they can threaten the lives of livestock and humans from inhalation of large swarms or by allergic reactions and blood loss from many bites.
Biting midges, also called “punkies,” and “no-see-ums,” are around 1/32 inch in length. Due to their small size, they can sometimes fly through window and door screens. The larvae of biting midges live in moist sand or soil, decaying vegetation, tree holes and near ponds, rivers, creeks or marshes, so the adult flies can be pests around these waterways.
Sand flies are around ¨û inch in length, hairy and brown to gray in color, with wings that form a “v” when at rest. The sand fly larvae live in moist, decaying vegetation, moss, mud or in water. Most feed on the blood of mammals, reptiles and amphibians. In many parts of the world, including South Texas, certain sand fly species are suspected of transmitting cutaneous leischmaniasis to humans, which is a disfiguring protozoan disease.
Ways to prevent bites
Repellents such as those containing DEET (N,N-diethyl-meta-toluamide) or picaridin is suggested to prevent most flies from biting. Avoiding wet areas inhabited by the biting flies and wearing light-colored, long-sleeved shirts, long pants and hats will prevent some flies from biting.
Non-chemical controls
Biting flies can be difficult to control due to all the moist habitats where the larvae can develop. Sanitation is always important, so all potential sites for larval development should be eliminated, and decaying vegetation should be disposed of. Screens should be installed and maintained on windows and doors, and finer mesh should be installed to keep out tiny biting flies, where these flies are a problem. Fans can also be used indoors and outdoors to keep areas free of flies, especially smaller flies that cannot withstand the air currents.
Chemical controls
Ultra-low-volume (ULV) treatments and sprays of non-residual pesticides can be used where flies are clustered in a small area. Residual pesticides can be used to spray surfaces where flies are resting, such as in vegetation and along the exterior walls of structures. Applications of Bacillus thuringiensis israelensis (Bti) or insect growth regulators, such as methoprene, have been used to control some fly larvae.
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"Rainbow" grasshopper, Dactylotum sp. (Orthoptera: Acrididae). Photo by Texas A&M University.
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Grasshoppers hopping at the end of summer
We may be seeing an overwhelming number of grasshoppers in the landscape at this time. This is due to our hot, dry summer, which favors grasshopper survival and reproduction. The female grasshopper uses its long ovipositor to deposit eggs ½ to 2 inches into the soil in the fall. The eggs hatch into nymphs in the spring or early summer, depending upon species. The nymphal stage lasts for around six weeks before molting into an adult with fully developed wings. The adult grasshoppers will be found until late fall or until a frost.
Grasshoppers feed mainly on weeds. However when the weeds begin to dry, grasshoppers will go into other areas in search of food (e.g., the plants in your landscape).
Non-chemical controls
• Controlling weeds will decrease the number of grasshoppers in an area. If weeds are removed, the grasshopper nymphs will starve, and the adults will lay fewer eggs in the area.
• Tilling the soil in the late summer will discourage female grasshoppers from depositing eggs, since they prefer to lay eggs in undisturbed soil.
• Floating row covers can be used to protect vegetable and flower gardens and small fruit trees from grasshoppers. The fabric allows sunlight through, while protecting plants from insects.
Chemical controls
Monitor grasshopper infestations, and treat when grasshoppers are in the nymphal stage. The immature grasshoppers are more susceptible to insecticides. Some effective insecticides include the active ingredients diflubenzuron, cyfluthrin, bifenthrin, and permethrin. In addition, baits can be applied, such as those containing a protozoa, Nosema locustae.
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Fire ant mound in a landscape. Photo by Dr. Bart Drees, professor and Extension entomologist, Texas A&M University.
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Remember to treat for fire ants this fall
Remember that the end of summer means treating for fire ants! Because the weather has been so hot this summer, we might not see fire ant mounds in our yards. However, they are still in the area and are living deep in the soil. Since fire ants are a medically important insect pest, we need to treat this fall to decrease their populations next spring.
Before treating for fire ants, one must first survey the area to determine the number of mounds. If fewer than five mounds are present in a quarter-acre plot, then it is advised to treat the individual mounds with a bait, drench or dust. If more than five mounds are present, then treatment should be broadcast over the entire area. A fire ant bait or contact insecticide may be used. Both baits and contact insecticides can be broadcast using a hand-held spreader for small areas, or a Herd Seeder mounted on a truck or ATV for larger areas.
For more information, please visit the fire ant webpage at http://fireant.tamu.edu.
About the author: Kimberly Schofield is a program specialist in the field of urban integrated pest management at the Texas A&M Research Center in Dallas.
Mention of commercial products is for educational purposes only and does not represent endorsement by Texas AgriLife Extension or The Texas A&M University System. Insecticide label registrations are subject to change, and changes may have occurred since this article was written. The pesticide user is always responsible for applying products in accordance with label directions. Always read and carefully follow the instructions on the container label.
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