The word 'locust' entered Middle English around 1200 from Old French 'locuste,' itself from Latin 'locusta.' The Latin word is one of etymology's more curious specimens: it denoted both the swarming grasshopper that devastated crops and the lobster that inhabited the sea. The Romans apparently perceived a structural similarity between the two creatures — both possess segmented exoskeletons, jointed appendages, and elongated bodies — and used a single word for both. The deeper origin of 'locusta' is unknown; no convincing Indo-European etymology has been established, and the word may be a pre-Latin substrate borrowing.
The dual meaning of 'locusta' left a lasting imprint on the Romance languages. Spanish 'langosta' (from Vulgar Latin *lacusta, a variant of 'locusta') still means both 'lobster' and 'locust,' with context determining which creature is intended — a fisherman's 'langosta' is a lobster, while a farmer's 'langosta' is a locust. French split the meanings: 'langouste' became specialized for the spiny lobster, while 'locuste' was retained for the insect, though the more common modern French term for locust is 'criquet pèlerin' (pilgrim cricket) or 'sauterelle' (jumper). Portuguese 'lagosta' settled
English inherited only the insect meaning. The marine creature had already been named 'lobster' from Old English 'loppestre' (possibly a corruption of Latin 'locusta' itself, via a separate early borrowing path, though the details are disputed). The result is that English 'locust' and 'lobster' may ultimately derive from the same Latin word, having arrived in the language by different routes at different times and settled on different referents.
The locust holds a unique place in the cultural imagination, particularly in the Abrahamic traditions. The eighth plague of Egypt in the Book of Exodus is a locust swarm, and the image of locusts darkening the sky and consuming every green thing became a powerful biblical metaphor for divine punishment and overwhelming destruction. John the Baptist is described as eating 'locusts and wild honey' in the wilderness — a passage that has generated centuries of debate about whether 'locusts' here means the insects (a common food source in the ancient Near East, still eaten today in many cultures) or the pods of the carob tree, sometimes called 'locust beans.'
The biology of locust swarming is as dramatic as the word's history. Locusts are not a separate species but a phase of certain grasshopper species. Under crowded conditions, desert locusts (Schistocerca gregaria) undergo a remarkable transformation — a phase change triggered by serotonin — from solitary, cryptically colored individuals to gregarious, brightly colored swarm members. A single swarm can contain billions of individuals covering
German took a completely different approach to naming this insect. 'Heuschrecke' literally means 'hay-frightener' (from 'Heu,' hay, and 'Schrecke,' from 'schrecken,' to frighten), vividly capturing the farmer's perspective — the creature that terrorizes the harvest. This descriptive Germanic strategy contrasts with the opaque Latin borrowing that English adopted, and arguably communicates more about the insect's ecological impact in a single compound word than 'locust' manages with all its classical ancestry.