What is a significant characteristic of the army worm in crop damage?

The significant characteristic of the army worm in crop damage is its movement in large numbers. Army worms are known for their swarming behavior, which allows them to cause extensive and rapid damage to crops. When they appear in large populations, they can strip entire fields of foliage within a short time, leading to severe economic losses for farmers. This mass movement and feeding behavior are key features that distinguish them from other pests which may not exhibit such overwhelming presence and impact.

The other characteristics, while they may pertain to different pest behaviors or effects, do not encapsulate the army worm's most notable threat to crops as effectively. Roots feeding pertains to pests that damage the root systems directly, which army worms do not primarily do. Leaf burrowing describes a different type of pest behavior where insects create tunnels in the leaves, typically seen with pests like caterpillars that remain stationary in their feeding sites rather than moving en masse. Transmitting diseases is also a characteristic associated with certain pests, but army worms are not known for this trait; their primary damage comes from their relentless feeding rather than disease spread.