**14.5 Tsetse flies** *Glossina* **sp.**

known as biting house flies. They can be distinguished from house flies and other similar looking flies by their forwarded pointing mouthparts. They may be confused with tsetse flies (Glossina), and these can be distinguished from tsetse flies, which also have forward-pointing mouthparts, by their smaller size and the position of wings, which do not overlap at the back in stable flies when at rest. These create painful bites and are a severe annoyance to humans and animals. They are not significant as vectors of diseases. But, they occasionally play a part in spread of myiasis by carrying eggs of myiasis-producing fly *Dermatobia hominis*

Fly *Stomoxys calcitrans* (**Figure 16**), is commonly called the stable fly, barn fly, biting house fly, dog fly or power mower fly. Unlike most members of the family Muscidae, *S. calcitrans* (sharp mouth plus kicking) and others of its genus suck blood from mammals. The eggs are put down in decomposing vegetation or manure and in the same location, larval and pupal stages progress by taking nearly 3 weeks to complete life cycle. Equally, females and males are blood feeders and severe pests of both animals and man. The larvae are creamy white in color and resemble those of the house fly. The pupae develop in dry areas in the soil. Development from egg to adult takes from 12 days to 2 months, depending on the temperature. They are not as important as vectors of disease; however, stable fly can transmit many organisms including anaplasmosis, anthrax and other blood-borne organisms [82].

Although a small fly, the adult of this species (Muscidae) is one of the most important ectoparasites of pastured cattle. Adults are half the size of a house fly (7 mm), gray in color with the large compound eyes and reduced antenna (**Figure 17**). In the life cycle, the eggs are laid on newly passed feces. Larvae are approximately 7 mm long, of pale yellow color and with a simple elongate body that lacks a sclerotized head. In that atmosphere, the complete life cycle takes place, generally taking about 2 weeks for completion. Typically, the adults exist in great numbers along the withers, base of the horns and caudal folds. The adults stay on animal for the whole time (excluding when eggs are being set down), however they feed only once or twice a day and males and females both are blood feeders. The adults fly typically takes position by face downward when sitting on an animal. Besides loss of blood along with heavy constant invasion, this fly looks to cause an excessive annoyance and irritation. Infection conduction comprises anaplasmosis

(Linnaeus) [81].

*Life Cycle and Development of Diptera*

**14.4 Horn fly** *Haematobia irritans* **(Linnaeus)**

and other blood-borne organisms.

**Figure 17.** Haematobia irritans*.*

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Tsetse flies occur only in tropical Africa and include all the species in the genus *Glossina*, which are placed in their own family Glossinidae. They are yellowish or dark brown, medium-sized flies and 6–15 mm in length. They can be distinguished from other large biting Diptera by their forward-pointing mouthparts. Tsetse flies bend their wings completely once they are relaxing so that one wing directly rests on top of other above their abdomens. Tsetse fly has also a long proboscis that spreads directly frontward and is attached to bottom of its head by a distinct bulb. Both sexual category are blood feeders and nourish on a wide-ranging of hosts also comprising man. Eggs hatch in the body of female and later on larval growth takes place, and then dropped larvae pupate instantly. The pupal stage nearly lasts for 3 weeks. This fly is a powerful vector for some diseases of man and animals comprising trypanosomiasis. They have a prominent economic impact in sub-Saharan Africa as the biological vectors of trypanosomes, which cause human sleeping sickness and animal trypanosomiasis, for instance, *Glossina brevipalpis* (Newstead) (**Figure 18**) is a vector of *Trypanosoma congolense* and *Trypanosoma vivax* [84].
