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any of approximately 370 species of primitive, wingless insects of the subclass Apterygota that measure from 5 to 20 mm (0.2 to 0.8 inch) in length when they are fully grown and have three slender, bristlelike appendages at the tip of the abdomen. The compound eyes are small and the mouth parts are external. Some species have scales covering the body. Young bristletails resemble adults except in size. Sexual maturity is attained in two to three years, and the life span of some species may be as long as seven years. A bristletail molts as many as 35 times during its life (three to five times per year). Bristletails eat starchy material, often causing damage to books and papers. Bristletail is also the common name for members of the order Archaeognatha, which is now separated from the Thysanura.