Gardening can be so rewarding but there are also many pests around. If you grow celery you may have noticed caterpillars on it. These tend to show up in gardens on any number of plants. The thing to think about is whether or not they are harmful. You don’t want your produce to be toxic to anyone.
- Caterpillars of the black swallowtail butterfly is celery worms. The young worms resemble bird droppings, then develop dark and light strips with bright yellow spots as they age.
- The black swallowtail butterflies are not species in danger of extinction. They may not indicate a serious problem. You can leave them on the plants or exterminate them.
- They can be controlled by handpicking if only a few, and by spraying with Bacillus thuringiensis, best on young caterpillars or Neem spray on older ones.
“Gardeners often feel more regret about dispatching butterfly caterpillars than they would about exterminating stinkbugs or garden spiders.”