The mating mechanism of T. lineola has not often been observed experimentally or in the field so little is known regarding their mating system.
After mating, Tabanus lineola females require a blood meal from a vertebrate host in order to oviposit her eggs. Females then need to select a suitable oviposition site, generally on the tips of salt marsh grasses. Tabanus lineola lays an average egg mass size of 208 eggs, which takes approximately 30 minutes to complete. Female flies obtain energy for the oviposition from stored carbohydrates. After several days, spindle-shaped larvae hatch which measure an average 2 mm in length. This species completes 8 to 10 instars. After completing the last instar, larvae will pupate. Pupae average 11 to 19 mm in length. The pupal stage typically lasts from 7 to 16 days, after which a sexually mature adult emerges.
Breeding season: Tabanus lineola breed in the spring and summer months, which varies geographically.
Average eggs per season: 208.
Key Reproductive Features: semelparous ; seasonal breeding ; sexual ; fertilization ; oviparous
There is little available evidence of parental investment for Tabanus lineola.
Parental Investment: no parental involvement; pre-fertilization (Provisioning, Protecting: Female)
Tabanus lineola may sense changes in its environment such as variation in temperature and cloud cover. Behaviors and flying activity may change in response to these external changes. For example, a temperature drop will cause flight activity to decline and thus T. lineola are less active in times of cooler temperatures. There is currently little significant research in regards to what sense organs allows these flies to perceive environmental changes or how T. lineola communicates with one another.
Tabanus lineola is found across a broad distribution and is especially common in the eastern parts of North America. This species appears to be fairly easy to capture for experimental purposes due to their abundant presence. Being that they are so common, they do not appear to be at any risk of endangerment. There are currently no conservation efforts because of the negative impact this pest has on humans and domesticated animals.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Tabanus lineola goes through holometabolous metamorphosis as a means of development. Tabanus lineola always lays its eggs in clusters. The size of the group of eggs may vary but is usually about 10 mm long and 4 mm wide. Each individual egg is approximately 2 mm long and .3 mm thick. The eggs that are first deposited are white in color, but after about a day or so they gradually turn to a dark gray. The eggs remain this color until they hatch. The amount of time for incubation varies based on temperature, but lasts 3 to 5 days on average. The higher the temperature and more intense the sunlight, the faster the eggs will hatch.
The larval period for Tabanus lineola is about 48 days. Tabanus lineola larvae are usually pale white in color, although other colors such as light yellow or pink have been observed. The length of the larval stage is quite short and may only last a month. Larvae reside mostly in the mud of ponds. Tabanus lineola go through 8 to 10 larval stages or instars. The larvae of most Tabanidae will usually molt right after hatching occurs. However, this process has been seen to take a few days in T. lineola.
The pupal period of T. lineola is also brief, ranging from 7 to 16 days. The number of days may lessen in higher temperatures. Pupae are about 11 to 19 mm long and 3 mm wide. After the pupal state, an adult T. lineola emerges from the pupa. Often this emergence occurs in a dry and sandy environment. The total development period of T. lineola, including egg, larval, pupal, and the period before oviposition is approximately 69.9 days.
Development - Life Cycle: metamorphosis
Tabanus lineola is a major annoyance to domesticated animals being that they suck their blood for nutrients. This causes a decrease in livestock production because the animals may experience irritation, a large loss of blood, and exposure to diseases vectored by T. lineola. Humans must try to methodically control these pest populations so that livestock production is not affected. There have been efforts to prevent T. lineola from harming domesticated animals through the use of insecticides, such as fenvalerate. Although some T. lineola are unharmed by these efforts, many are killed or unable to feed on enough blood. Many flies have built up a resistance to these insecticides so they may no longer be effective. An alternative possibility in controlling these pest populations is to infect them with spiroplasmas.
Negative Impacts: injures humans (bites or stings); causes or carries domestic animal disease
Tabanus lineola does not appear to have any beneficial effects on humans.
This species acts as a parasite to both domesticated animals, such as hogs, horses, and mules, as well as humans. At every stage of its life, Tabanus lineola serves as prey to a wide variety of other organisms. Adults of this species are also potential pollinators for local plants, due to their mainly nectivorous diet.
In addition to acting as a parasite, there has also been occurrences of Tabanus lineola being the infected host for the larvae of arterial worms (Elaeophora schneideri). Although third stage larvae of this species have been found to infect T. lineola, the prevalence is quite low. Tabanus lineola are also hosts for bacteria of the genus Spiroplasma. They most likely acquire these bacteria through their environment as it is passed to other flies at common feeding sites that contain carbohydrates like honeydew or tree sap. This association may allow humans to control T. lineola populations using spiroplasmas.
Ecosystem Impact: parasite
Species Used as Host:
Tabanus lineola feeds on both the blood of its hosts as well as plant nectar. Only females feed on blood, which is primarily used for oviposition and the development of eggs. Their digestive systems are unique and are able to store the ingested sugar and blood separately. Adults will feed on blood by cutting through their hosts' skin and suctioning out a blood meal. Common hosts include cattle, horses, mules, and humans. They usually will feed from about 9 a.m. to 6 p.m. Although blood meals are required for successful reproduction, females who cannot obtain blood meals may still live just as long as those who do. Therefore, is can be assumed that carbohydrates are what keeps T. lineola alive rather than nutrients in blood.
When reared in captivity, larvae are known to feed on various foods. They appear to prefer snails, worms, and the abdomen of crustaceans. However, when larvae are about to transform between instars during development, they experience a time of complete rest where the will refuse any food.
Animal Foods: blood; mollusks; terrestrial worms; aquatic crustaceans
Plant Foods: nectar
Primary Diet: herbivore (Nectarivore )
Tabanus lineola has been found to exist across all of the United Sates and Canada. This species is principally found in coastal regions across eastern and southern United States. Tabanus lineola is present in great density in places such as Ohio, Michigan, Alabama, and South Carolina. This species is also commonly found along the coast of New Jersey and Georgia.
Biogeographic Regions: nearctic
Tabanus lineola mostly resides in coastal salt marshes and wetlands. The majority of flies are found 1.5 to 3 feet from the surface of the salt marsh. Tabanus lineola temporarily spends time on its hosts which include humans and several domesticated animals such as horses and hogs.
Habitat Regions: temperate ; terrestrial ; saltwater or marine
Aquatic Biomes: coastal
Under laboratory conditions, female flies may survive 4 or 5 days without a source of carbohydrates. Others, who are provided carbohydrates may survive up to 42 days.
Status: captivity: 2 to 42 days.
Tabanus lineola is a striped, green-headed horse fly. The length of this species is approximately 12 to 15 mm. Tabanus lineola weighs approximately 50 milligrams and its total volume of blood accounts for about 20% of this mass. They have large, bright green eyes, which usually feature a purple stripe crossing over them. This species has either a black or brown abdomen containing three gray stripes. The appearance of T. lineola may slightly vary between flies living in different habitats. Those found in coastal habitats may be lighter in color with wider frons than those found inland. This species exhibits no sexual dimorphism.
Average mass: 0.050 g.
Range length: 12 to 15 mm.
Sexual Dimorphism: sexes alike
Other Physical Features: ectothermic ; bilateral symmetry
There is little available information regarding the predators of Tabanus lineola. Larvae are very vulnerable, and are likely consumed by many insectivorous organisms including birds, amphibians, reptiles, mammals, and other insects. Adult flies are likely predated by birds and possibly predatory wasps. Tabanus lineola egg masses are known to be eaten by seriate lady beetles.
T. lineola females have a pale median stripe on their abdomen and are known for biting. The male does not bite and lacks hair on eyes.