Allacrotelsa spinulata

The species name 'spinulata' refers to the small spines on the caudal filaments, a key diagnostic feature distinguishing it from other Allacrotelsa species and many Lepismatidae. The genus Allacrotelsa is separated from the common silverfish genus Lepisma by differences in abdominal sternite structure and chaetotaxy. Accurate identification to species level requires examination of caudal filament spination and other microscopic features.

Elongate, flattened, wingless insect with a silvery-gray coloration. Body covered in scales. Three long, thread-like caudal filaments (two lateral cerci and one median caudal filament) extend from the abdomen tip. Distinguished by the presence of prominent spines on these filaments, as indicated by the species epithet 'spinulata'. Antennae are long and filamentous. Compound eyes are absent or reduced; ocelli may be present. Body length approximately 10-15 mm.

Has been observed in human-modified environments including buildings, basements, and storage areas, as well as natural habitats such as leaf litter, under bark, and in rock crevices. Prefers dark, humid microhabitats with stable temperatures.

Documented from North America. Distribution records indicate presence across the continent, though specific range boundaries are not well-defined in available sources.

Active year-round in suitable microhabitats, particularly indoors. Activity patterns likely influenced by humidity and temperature rather than photoperiod.

Feeds on materials containing starch, cellulose, and proteins. Documented food sources include paper, book bindings, glue, cereals, and other stored products. Also consumes detritus and decaying plant matter in natural settings.

Development is ametabolous (no metamorphosis). Juveniles resemble adults in form, differing only in size and sexual maturity. Molting continues throughout life, with individuals capable of numerous molts. Reproduction involves indirect sperm transfer via spermatophores deposited on substrate. Females lay small numbers of eggs in crevices.

Nocturnal and thigmotactic (seeking contact with surfaces). Rapid, sinuous running movements when disturbed. Cannot climb smooth vertical surfaces as effectively as some other silverfish species. Aggregates in favorable microhabitats.

Decomposer in natural ecosystems, breaking down cellulose and organic detritus. In human environments, acts as a nuisance pest of stored products and paper goods. Serves as prey for various arthropod predators including spiders and centipedes.

Household pest of minor economic importance. Can damage books, documents, wallpaper, and stored food products. Control typically involves reducing humidity and removing food sources rather than chemical treatment. Not known to transmit disease.

• Lepisma saccharinaCommon silverfish; distinguished by lack of prominent spines on caudal filaments and different abdominal sternite structure
• Ctenolepisma speciesOther domestic silverfish; separated by differences in scale patterns and caudal filament morphology

• silverfish
• household pest
• wingless insect
• North America
• decomposer
• thigmotactic

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon