Eastern Africa is being threatened by giant swarms of locusts which are feeding and breeding in the Horn of Africa, according to the chairman of the seven-nation Desert Locust Control Organization of Eastern Africa. The official, John Malecela, who has just returned from an inspection tour of locust-infested areas of Ethiopia, said: "The situation is very dangerous."

For the impoverished countries of eastern Africa, where just feeding the population is a massive task, destruction wrought by locusts can readily lead to famine. The situation is complicated by political conflicts and unusually heavy rains in the locust-breeding areas.

The desert locust has, down through the ages, been a scourge to subsistence farmers from Morocco to India. The latest outbreak, the worst since 1969, has brought about unified action by the seven often warring countries of eastern Africa. Yet their scant resources - the Locust Control Body's annual budget is only $2 million - are inadequate for an effective offensive against the flying pests.

"Our organization cannot control the situation alone," explained Malecela.

The organization's chairman, who is Tanzania's minister of agriculture, made an urgent appeal for international assistance which "must arrive within the next two months."

Malecela reported that so far 43 swarms have been spotted in Ethiopia and 17 in Somalia, most spreading over 10 to 40 square miles.

"I want to stress that what I saw was something very very serious. It was frightening. At times the locusts were so thick our pilot could not see out the windscreen of the plane," he said.

Malecela said that one square mile of locusts devours 14 tons of vegetation each day and travels over 100 miles. This means that at the moment the locusts in the Horn of Africa are eating between 8,000 and 34,000 tons each day.

A specialist for the U.S. Agriculture Department said it is estimated that a ton of locusts can eat as much food each day as 250 persons. The specialist, H. Charles Treakle, of the department's Economic Statistics and Co-operative Service, said that there can be "many, many tons" of locusts in a single swarm.

Two weeks ago Ethiopia said that from 600,00 to 1 million people were facing starvation in the northeastern province of Wollo because of the locusts, drought and ergot, an agricultural disease.

Ethiopia, which has pledged $1 million to fight the current infestation, has appealed to its people to report any new swarms and attack them with tradional methods, including burning, and beating them and burying them in pits.

Nevertheless, the most effective - and most costly - method is aerial spraying with insecticides.

Malecela said the locusts entered the Horn about 12 months ago from North Yemen and Saudi Arabia. He explained that control has been complicated because "most of the breeding areas are where there have been recent political troubles - in Eritrea, between Dijibouti and Ethiopia. Therefore, the breeding was not properly controlled and there has now been a great outburst."

Malecela said there is a grave danger that the locusts will move south.

"Millions of new locusts will hatch in August and September. Then towards the end of the year when the monsoon winds start blowing south it will be very easy for the locusts to be brought into Kenya and northern Tanzania."

His organization, which represents Tanzania, Kenya, Uganda, Sudan, Somalia, Ethiopia and Djibouti and is headquartered in Addis Ababa, Ethiopia, has drawn up a list of requirements they are seeking from international aid agencies. It includes vehicles, radios, insecticides and $1 million dollars for expenses and additional staff.

About 50 countries from the Atlantic to the Himalayas may face a full scale locust plague unless Ethiopia and Somalia take immediate action against their outbreaks, the Food and Agriculture Oganization (FAO) warned yesterday.

Edouard Saouma, director general of FAO, added here that if the two countries did not keep their plagues from spreading, seasonal winds might carry swarms of the insect as far as Morocco in the west and Iran and Pakistan in the east.