Department of Entomology, Oklahoma State University, Stillwater, Oklahoma 74074
Keys, descriptions, distribution records, and host information are presented for the four species of earwigs known to occur in Oklahoma.
About 900 species of earwigs are known, most being tropical. They are most easily distinguished by the forceps at the tip of the abdomen. The forceps are used for defense, for seizing and holding prey while feeding, and for folding and unfolding the wings when wings are present. About 20 species are established in the United States. Many of these, including three of the four species found in Oklahoma, have been introduced from other parts of the world. Only Vostox brunneipennis (Serville) is thought to be native to Oklahoma.
Earwigs are not common in Oklahoma and only a limited number of collections have been available for study. Hopefully, this paper will stimulate interest in the group and more collections will be made in the future.
[Modified from Langston and Powell (1) and Helfer (2)]
|1||Antenna with 20 or more segments, segment I longer than segments IV-VI combined; large, winged species||Labidura riparia|
|Antenna with 12 to 16 segments, segment I equal to or shorter than segments IV-VI combined; smaller species||2|
|2||Adult wingless; femora with dark bands; two or three subapical antennal segments usually paler than other segments||Euborellia annulipes|
|Adults winged; femora not banded; antennae without pale segments||3|
|3||Eye longer than side of head behind eye; length 9-12 mm.; not heavily pubescent||Vostox brunneipennis|
|Eye shorter than side of head behind eye; length 7 mm. or less; body thickly pubescent||Labia minor|
Euborellia annulipes (Lucas)
Color dark brown except legs and subapical antennal segments, which are pale yellowish. Femora and often tibiae with brown bands. Male forceps asymmetrical, the right arm more strongly curved than the left. Antennae with 14 to 16 segments. Length 9 to 13 mm. A general feeder, damaging plants and plant products and also predaceous on other insects. Often found in buildings in Oklahoma but has also been taken in dead leaves and rotting manure out of doors.
County records: Jackson, Muskogee, and Payne.
Vostox brunneipennis (Serville)
Color brown, except legs and a large spot on the exposed portion of each wing lighter. Male forceps symmetrical, with a small tooth internally near the middle. Antennae with 12 to 16 segments. Length 9 to 12 mm. Found under loose bark of dead trees.
County records: Mayes and Tulsa.
Labia minor (L.)
Color brownish except legs, which are lighter. Most of body, legs, head, and antennae covered with short hairs. Male forceps symmetrical, with several small teeth internally. Antennae with 12 to 15 segments. Length 4 to 7 mm.
County records: Craig, McCurtain, Payne, and Pontotoc.
Labidura riparia (Pallas)
Color dark brown with appendages and variable markings on the body tan. Male forceps symmetrical, with a tooth internally past the middle. Antennae with 25 to 29 segments. Length 18 to 26 mm. Langston and Powell (1) conclude it is primarily predaceous, seldom feeding on plant material.
County records: One specimen, Perkins, Payne Co., 30 August 1964, at light, D.C. Arnold.
1. R. L. LANGSTON and J. A. POWELL, Bull. Calif. Insect Surv. 20: 1-25 (1975).
2. J. R. HELFER, How to Know the Grasshoppers, Cockroaches, and Their Allies, Wm. C. Brown Co., Dubuque, Iowa, 1953, pp. 13-18.