Entomophobia is a specific phobia characterized by an excessive or unrealistic fear of one or more classes of insect, and classified as a phobia by the DSM-5. More specific cases included katsaridaphobia (fear of cockroaches), melissophobia (fear of bees), myrmecophobia (fear of ants), and lepidopterophobia (fear of moths and butterflies). One book claims 6% of all US inhabitants have this phobia.
Entomophobia can be developed in some ways. One of them is by having a frightening experience or if the person believes that the insect is dangerous. For example, if the person thinks a butterfly is venomous, they will do anything they can to avoid getting close to it.
Entomophobia may develop after the person has had a traumatic experience with the insect(s) in question. It may develop early or later in life and is quite common among animal phobias. Typically one has a fear of one specific type of insect, but in some cases this may encompass most, if not all other insects, and possibly other animals of the phylum Arthropoda. Entomophobia leads to behavioral changes: the person with entomophobia will avoid situations where they may encounter the specific type of insect. Cognitive behavioral therapy is considered an effective treatment.