Sandflies are pale brown flies that move in a series of flying 'hops'. Flies live in the humid earthen burrows of rodents and other small mammals. In general, the flies feed at night after twilight. Eggs are deposited in warm, humid dark places. The flies have long slender bodies and it is the female that feeds on blood.
Transmission occurs through the mouthparts which are designed to cut the skin.
Tsetse flies are dark in colour, look similar to house flies and are almost entirely confined to sub-Saharan Africa. G. mortisans prefers open savanna environments whereas G. palpalis is more riverine in preference. In fact, they are of as much concern agriculturally as medically with infected flies rendering millions of square kilometres of land unusable for cattle-rearing. Both sexes of fly feed on blood and transmission to and from the fly takes place through mouthparts designed for biting. Flies feed during the day.