Found these tiny white barrel-shaped things neatly lined up on the underside of a leaf. They look like a microscopic drum set. Should I be worried?

you have repeated heavy infestations across multiple plants, then it may be worth talking with your local extension office about options appropriate for your crop and region. But for most home gardeners, eggs are the stage where physical removal is the smartest first move.

11. Where to check next if you found one cluster

Once you find one egg mass, inspect nearby leaves right away. Check the undersides of leaves within about 12 to 18 inches of where you found the first cluster, then move to neighboring plants. Focus on tender