Smith's Bible Dictionary
Palmer-worm. (Hebrew, gazam). Palmerworm occurs in Joel 1:4; Joel 2:25; Amos 4:9. It is maintained by many that gazam denotes some species of locust, but it is more probably, a caterpillar.
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Smith, William, Dr. Entry for 'Palmer-worm'. Smith's Bible Dictionary. https://www.studylight.org/dictionaries/eng/sbd/p/palmer-worm.html. 1901.