The flea beetles were so small that it was hard to see them with the naked eye. Under a magnifying glass, they were easy to watch: shiny, elongated, black insects, marching around on the surface of the broccoli foliage, munching as they went. But no such proof was needed. The damage was unmistakable — leaves stippled with holes so numerous that some were more hole than leaf.
Touch a flea beetle with your finger and it will disappear like magic, launching itself into the air with its strong hind legs — the leap that gives it its name — only to return and continue the business at hand. This pest is mostly a spring visitor that emerges from its winter home in the soil to gorge, then returns to the soil to lay eggs. These hatch into soil-dwelling larvae, but it’s the adult beetle stage that gives gardeners fits. (The larvae might nibble on the plants’ roots, but only with a root crop, chiefly the potato, is this a problem.) An attack on young seedlings, however, can do them in, because they have little foliage to spare. Some recover, some don’t, and for our broccoli the future did not look bright.