The life cycle of locusts is such that for many months of the year they are not a threat. But for five months of the year locusts can appear (depending on environmental conditions favourable to them). Within that five‑month window, locusts can appear in a given area for a short period before they ride the winds elsewhere. Again, it is possible that a second wave of locusts enters your area to attack your crop a second time. The point is that locusts are migratory pests so that they trouble you for short periods of time (though the result of their visit remains with you for a long time). The Lord, however, instructs these locusts to “torment them for five months,” which means that they do not move along but stay put so as to be able to torture continually—until their season is past.
5 They were allowed to torment them for five months, but not to kill them, and their torment was like the torment of a scorpion when it stings someone.