Army Worm
2 of the 7 encyclopedias on this shelf carry an entry for Army Worm. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
the caterpillar of a dull brown nocturnal moth. The larvae take the name from a habit of marching from field to field in a host. The full grown caterpillar is about an inch and a half long, and is marked with green, black, and yellow stripes. It may be found almost anywhere east of the Rocky Mountains , but attracts attention only in years of unusual prevalence. If taken in time, a colony may be extinguished by spraying with paris green . About the only way to stop the army-worm when on the march is to dig a shallow ditch, steep on the far side, with pits here and there. The "worms" follow the steep edge seeking a chance to climb up, and fall into the pits, where they may be taken by the bushel. Instances are not uncommon of fields of grain and of orchards destroyed by army-worms, but birds and parasites prevent their becoming a dangerous pest. See Insect 2026 Editor's Note: The marc hing caterpillar became a global threat this entry never foresaw: the fall armyworm , native to the Americas, invaded Africa in 2016 and swept across Asia, devouring maize and threatening the food security of hundreds of millions — now one of the world's most feared crop pests. (Ed: BR 2026-07-17)
Collier's New Encyclopedia (1921)
the very destructive larva of the moth heliophila or leucania unipuncta, so called from its habit of marching in compact bodies of enormous number, devouring almost every green thing it meets. It is about 1/2 inches long, greenish in color, with black stripes, and is found in various parts of the world, but is particularly destructive in North America. The larva of sciara militaris, a European two-winged fly, is also called army worm.