Gardening in 1910:

1. Observe damage. Obviously something's eating the plant.
2. Find culprits--ah, green caterpillars!
   
3. Pick and squish the critters.

Gardening in 2010:

1. Observe damage. Obviously something's eating the plant.
2. Google "Brussels sprouts" and "damage" and, oh, look, a new post by John Spencer....Remember why I turned on computer. Spend half hour reading about cabbage moth caterpillars, their economic damage, the identifying characteristics, their life cycle. Learn what cabbage moth eggs look like. Note that they're laid a single egg at a time. Google best way to control them.
3. Find culprits--ah, green caterpillars!
4. Pick and squish the critters.