PARIS — Desert locusts in Israel hatched and formed groups of juveniles known as hoppers for the first time in more than 50 years, threatening crops, the U.N. Food & Agriculture Organization (FAO) reported.

Spraying of hoppers is in progress to treat as many infestations as possible before the immature plague insects become adults that could form swarms and threaten agriculture, the Rome-based FAO wrote on its Locust Watch website today.

Adult desert locusts can eat their own weight of about 2 grams (0.07 ounces) in food daily, and swarms can cover several hundred square kilometers, with between 40 million and 80 million locusts per square kilometer (0.4 square miles), according to the FAO. The last time locusts hatched and formed hopper groups in Israel was in April 1961, the U.N. agency said.

“Hatching occurred from mid-April onwards in the western Negev Desert of Israel and in the Sinai Peninsula of Egypt where hoppers are now forming groups and bands in both areas,” the FAO wrote.

In Egypt, insecurity is hampering survey and control operations in the Sinai, according to the FAO. Locust breeding has been detected and hopper groups may be forming in inaccessible areas, according to the report.

Flying South

Any adult groups and swarms that may form in either country will probably fly south in June to summer breeding areas in the interior of central Sudan to western Eritrea, the FAO said.

Locusts are also breeding in Saudi Arabia, including on the edges of irrigated alfalfa crops. Groups of adults moved to the country’s interior and there’s a risk that small groups could reach southwest Iran and move east, the FAO said. Hopper bands are forming in Sudan along the Nile River that could threaten crops this month, it said.

The locust-risk level in Israel, Saudi Arabia, and Sudan is orange, the second-highest category, meaning surveys and controls must be undertaken and there’s a threat to crops, according to the FAO. The level is yellow in Egypt, a lower risk assesment that calls for increased vigilence.

In northwest Africa, spring breeding is in progress in the northern Sahara of Algeria and on the southern side of the Atlas Mountains in Morocco, according to the report. Spraying has taken place in Algeria, the FAO said.

Desert-locust distribution can extend over 60 countries during plague years, covering about 29 million square kilometers, according to the FAO.