When I was a small girl I went to an excellent Sunday school where we were introduced to lots of Bible stories with very few be-good-or-else threats attached. I learned a great many interesting things, including knowing by heart the seven plagues that were inflicted on Pharaoh and his people. This is where I first encountered locusts. As a child they were associated in my mind with the swarms of midges that can spoil many a summer evening on the west coast of Scotland.

Winston Churchill brought the phrase “the years the locust has eaten” into common British idiom in the 1930s by repeatedly referring to the period during which the U.K. failed to rearm, despite Germany’s doing so, as “the locust years.” The expression was taken up in other contexts. In woodland conservation literature, for example, the decades between 1950 and 1980 are called the locust years because of the way tax-incentivized plantations gobbled up vast areas of Scottish landscape, permanently damaging both views and ecology. Nowadays the term has become personal; people speak of difficult periods in their lives as locust years and often draw comfort from Joel’s prophecy.

Only recently have I begun to understand the terrible devastation that locusts inflict on agricultural communities. I used the expression fairly lightheartedly with a Moroccan friend, and she responded with both anger and distress. The 2004 desert locust invasion in Africa did not merely cause significant crop losses; it had an effect on harvests for the following two years, with a serious negative impact on the region’s food security.