Dar-e Kalan district, Afghanista ? In this Afghan offensive, village men are digging trenches to fight a relentlessly advancing enemy whose hunger for territory is both legendary and insatiable: locusts.

Northern Afghanistan, which has endured poverty, war, drought and hunger, is now facing its worst plague of locusts in nearly 30 years, U.N. Food and Agriculture Organization officials say.

The insects are threatening the part of the country hit hardest by three years of drought just as it is finally blooming with crops and with peace.

Locusts are not new here, but they have thrived while many Afghans have been spending more time killing each other than combatting their common six-legged foe.

The end of the drought and a mild winter also helped locusts breed, said Andrew Harvey, an FAO official in northern Afghanistan’s main city, Mazar-e-Sharif, and the general in the agency’s war against the pests.

Aid groups have declared an emergency situation and are racing against time in the “locust triangle” a region between the northern cities of Kunduz, Pul-e-Khumri and Samangan where the insects are most concentrated.

By late next week, the locusts, now just able to hop, will finish growing wings and take to the skies, becoming much harder to control.

“We’re really anxious that people don’t see their last effort of growing crops go down the jaws of locusts,” Harvey said.

On Friday, a leaping horde of thousands of brown locusts was eating its way across hills green with a light stubble of fresh growth in Dar-e Kalan district, 50 miles southeast of Mazar-e-Sharif. Clusters of the bugs piled on to any piece of greenery they could find across their twisting line of advance, which extended hundreds of yards across the valley.

In their way stood a group of about 50 men from local villages. As a tractor dug a small trench ahead of them, the men waved pieces of plastic, scarves and blankets to herd the swarm into the hole where they crushed them with their feet.

Abdul Ghafar, 50, an Islamic studies teacher, took the day off Friday to fight against what he labeled nothing less than “the enemy of the people of Islam.”

“We have to kill all the locusts. We have gardens, we have shops, we have houses in the city,” he said. “They will eat everything.”

The manual effort “makes a difference how big of a difference depends on how many people you can motivate,” said Jonathan Brass, an agriculturalist with the Irish aid agency GOAL, which is helping fight the locust menace. “Every day they’re out doing this, they’re not earning anything.”