ABSTRACT
Diagnosis: L. 10-12 mm; body soft, with flexible integument; white, gray, or yellowish gray to brown; body somewhat flattened, with pigmented scales. Mouthparts primitive, mandibles long, with a single condyle and a molar area well separated from the terminal incisor. Large compound eyes, meeting dorsally; ocelli present. Thorax strongly arched. Abdominal segments 2 through 9 with ventral styles and 1 through 7 usually with one or two pairs of exsertile vesicles. Median apical ftlament much longer than the lateral cerci. Immature stages resemble the adult with no noticeable external metamorphosis. This group, once considered a part of the order Thysanura, is now placed in a separate subclass of the insects, the Archaeognatha, a classification based primarily on the structure of the mandibles, but also on features of the eyes (for example, the ommatidium is primitive, resembling that of the Collembola, with only a single-layered retina and other details).
