Earwigs, belonging to the insect order Dermaptera, are recognized by their elongated bodies and the distinctive pincer-like appendages (cerci) at their rear. These insects are a frequent sight in gardens and homes. While the vast majority of the approximately 2,000 earwig species are quite small, the range of size across the order is much wider than most people expect. Size variability depends greatly on the specific species encountered and whether the measurement includes the cerci.
Typical Dimensions of Common Earwigs
The earwig most often encountered in North America and Europe is the European earwig, Forficula auricularia. This species sets the standard for typical earwig size, representing the dimensions of the insects that most people find around their homes. The main body length of an adult European earwig usually falls within the range of 12 to 16 millimeters (roughly a half-inch to five-eighths of an inch).
This measurement represents the standard body length, excluding the prominent pincer-like structures called cerci at the end of the abdomen. The size of this common species is typical for the majority of earwigs found worldwide, making them relatively small insects overall.
The Absolute Maximum: Record-Holding Species
The question of how big earwigs can get is answered by an exceptional species, the Saint Helena giant earwig, Labidura herculeana. This massive insect was endemic to the remote island of Saint Helena in the South Atlantic Ocean and represented the absolute maximum size for the order Dermaptera. The largest recorded specimens reached a total length of up to 84 millimeters (approximately 3.3 inches), including its powerful cerci.
This enormous size is a geographical anomaly, contrasting sharply with the small dimensions of common species. The Saint Helena giant earwig’s body length alone could be up to 53 millimeters, significantly larger than any other known earwig. Unfortunately, this record-holder is now classified as extinct by the International Union for Conservation of Nature (IUCN), with the last live sighting occurring in 1967. The species’ extinction is attributed to habitat destruction and predation from invasive species like rats and centipedes.
Why Earwigs Look Bigger Than They Are
A common reason earwigs are perceived as larger than their actual body length suggests is due to the visual impact of their cerci. These prominent, forceps-like appendages extend directly from the rear of the abdomen, adding considerable visual length to the insect. While scientific measurements often focus only on the length of the main body, the overall impression includes these long, intimidating structures.
The cerci themselves can be substantial, especially on males of the common European earwig, where they may measure up to 9.5 millimeters. Male earwigs generally possess longer and more curved cerci compared to the shorter, straighter structures found on females. This sexual dimorphism means that the largest visually perceived earwigs an observer sees are often males of the species. The combined effect of the body and the cerci creates a total length that is more pronounced, making the insect appear significantly more substantial than its core body size would indicate.