Biting flies alter livestock routines during Khareef

SALALAH, AUGUST 22
For livestock owners in Dhofar, the night-time movement of cattle is a familiar feature of Khareef — a seasonal routine shaped by tiny blood-feeding flies whose numbers increase as the monsoon transforms the mountains.
During this period, many cattle are kept in dark shelters during the day and released to graze after sunset, reducing their exposure to the biting insects.
For Mohammed bin Muslim bin Ahmed, who raises cattle and camels, the arrival of the seasonal flies changes not only when his animals graze, but also where they are taken.
“When the fly season begins, the cattle remain inside during the day,” he told the Observer.
Camels are managed differently. “We take them out early in the morning before sunrise and allow them to graze for a short time,” he said. “When the sun rises, we move them away from the grazing areas.”
Some are taken to drier ground between the mountains and the Nejd, where pasture is limited and the influence of Khareef is weaker.
“These are dry places where Khareef does not reach strongly, and they are more suitable for camels during this period,” Mohammed said.
Other livestock owners move their camels towards the coastal plain, where he said the biting flies are considerably less troublesome.
“Some of our people move towards the plain near the sea, where the effect of these flies is much weaker,” he said.
His account reflects a wider seasonal pattern across rural Dhofar. While cattle alter their grazing hours, some camel herds change their location altogether.
Scientific research shows that the phenomenon involves several species of blood-feeding flies rather than a single species.
A 2011 study published by Sultan Qaboos University identified Haematobia minuta, Musca crassirostris and Forcipomyia whitcombei among species that feed on domesticated animals in Dhofar.
The study found that the flies can restrict grazing in some areas during the rainy season, making them a limiting ecological factor.
Their seasonal abundance is closely linked to the environmental changes brought by Khareef.
For much of the year, Dhofar’s mountain environment is relatively dry. During the monsoon, persistent moisture, fog and drizzle stimulate rapid vegetation growth, while wet soils and organic material remain moist for longer.
These conditions can also create favourable breeding environments for biting flies.
Sultan Qaboos University notes that wet soil, animal manure and decomposing vegetation are among the environments in which some biting flies can breed.
One of the best-known locally is Forcipomyia whitcombei, commonly referred to as Al Arnout or Al Khanyout. Sultan Qaboos University says the tiny biting fly is particularly common around mountain and spring areas, with activity concentrated mainly between July and September.
Al Arnout, however, is only one component of the wider phenomenon affecting livestock.
The available scientific evidence does not support treating all of Dhofar’s seasonal biting flies as a single species, nor does it establish a precise date when the phenomenon begins or peaks.
Rather, the wider Khareef period creates environmental conditions that allow these insects to flourish. As the season recedes and the landscape becomes drier, those conditions diminish.
The response described by Mohammed is not new.
The 2011 SQU study documented precautionary measures used by Dhofar’s pastoralists against blood-feeding flies, including changes in grazing practices during Khareef.
A separate study of contemporary pastoralism in Jabal Qamar, published in Human Ecology in 2020, provides further evidence of seasonal movement.
From around mid-June to mid-September, researchers found that abundant moisture stimulates vegetation growth, soils become saturated and blood-feeding flies become more prevalent.
The conditions are particularly challenging for camels. The study found that camels and goats are moved from the escarpments towards the plateau or coastal plains during Khareef, while cattle generally remain on the escarpments.
The scientific findings closely mirror what livestock owners continue to describe on the ground.
It is a pastoral system based on reading both time and terrain — knowing when insects are most active, where Khareef moisture is strongest, where the ground becomes too wet and where animals can be moved to drier conditions.
The insects may also have a less obvious effect on Dhofar’s vegetation.
The 2011 SQU study suggested that by restricting livestock grazing in certain areas during Khareef, blood-feeding flies can act as a natural limiting factor, indirectly giving vegetation more opportunity to grow during its most productive season.
That does not mean the insects are beneficial to livestock. Their bites cause irritation and restrict the time and areas available for grazing. The same SQU research noted that the potential for these flies to act as disease vectors had not been investigated in Oman.
In 2024, Sultan Qaboos University said detailed knowledge of the biology and population dynamics of Al Arnout in Oman remained limited. Dhofar Municipality, working with academic and government institutions, has supported research aimed at developing more effective and sustainable methods of managing the insect.
For livestock owners, however, adapting to the flies remains part of the annual rhythm of Khareef.
The consequences become particularly visible after sunset.
Cattle leave their shelters and head towards pasture, sometimes appearing on mountain roads just as darkness, fog and drizzle reduce visibility.