Yahweh keeps them safe from locusts (Mal 3:11-3:11)

“‘I will rebuke

The locust

For you.

Thus,

It will not destroy

The produce

Of your soil.

Your vine

In the field

Shall not be barren.’

Says Yahweh of hosts.”

Yahweh, via Malachi, said that he was going to hold back the locusts from them.  These locusts would not destroy the products that they planted.  In fact, their vineyards would not be barren, but fruitful.