Ichneumon flies are part of a diverse group of parasitic wasps that use other insects as hosts for their eggs. There are several synonyms for the term ichneumon fly, including the ichneumon wasp, ichneumonid, and ichneumonoid. These insects are recognized for their long ovipositor, which they use to implant eggs into the host insect, often causing its death. Another term that is used to describe ichneumonid wasps is the "parasitoid," which highlights their behavior of parasitizing hosts but often killing them in the process. There are over 100,000 species of ichneumonids, making them an important component of many ecosystems.