A Rite to Kill

Wendy Adams was the island's top gardener. She had tremendous success with all types of plants. She even grew a lot of things that wisdom said would not grow there.
When asked how she managed to keep such healthy plants in that kind of insect-infested place she answered that she had almost a set of rites she always followed. It got rid of the pests very effectively.
Then a few pests died in her garden who were not insects, snails, mites, or mice.