Silverfish

Silverfish

Structure, Appearance and Characteristics

• Body flat, long and slender, tapering toward rear.
• Covered with scales.
• Series of bristle combs on back
• Antennae long and slender.
• Wingless.
• Chewing mouth parts.
• Three long appendages, i.e. a pair of cerci and an appendix dorsalis
• Often silver in colour.
• Size varies from 15-25mm for mature adults.
• Young are similar to adults but smaller.
• Fast moving.
• Nocturnal - prefer dark undisturbed places
• Cannot climb smooth surfaces.

Life Cycle

Primitive metamorphosis. (Egg – nymph – adult (continual moult). Eggs laid singly or in small batches (2-20). Eggs are light-yellowish and about the size of a pinhead. Eggs hatch in 2-8 weeks. 1st Instar - no scales, stylets. 4th Instar - scales appear, one pair of stylets. 9/11th Instar - other pair of stylets. 13th Instar - sexually mature. Sexual maturity in 24-36 months. Adult life span up to 4 years. Adults continue to moult through entire life. Favoured breeding temperature 24 C.

Habitat

Natural - Under bark, leaf litter, rotting logs. Prefer warm temperatures. Activity ceases below 13 C. Death occurs above 40 C. Indoors - Found in roof cavities, wall voids, subfloor areas and within dwellings. Found around heat / water sources.

Food

Foods containing proteins and carbohydrates (e.g. rolled oats, flour, starch, sugar, glue, linen and some synthetic fibres.) Can live for long periods of time without food. Often do not feed during last third of each instar. Omnivorous. Feeding marks are irregular and may not even penetrate paper.

Pest Status

Consume small amounts of human foods.Contamination with scales and droppings. Considerable damage to natural/synthetic fibres, books and other paper products while trying to feed on glues or other starchy substances (e.g. wallpaper). Can leave yellow stains, especially on linens. Adults and nymphs are both considered pests.

Control

Strengths are agility and speed, variety of food sources and habitats especially in the human environment, can survive in cooler temperatures. Weaknesses include lack of ability to climb smooth surfaces resulting in being trapped in open places such as baths. Because of a preference for darker, secluded areas, susceptible commodities such as books etc should be checked and if necessary storage of such items changed to environments less suited to silverfish. Chemical treatments involve dusting or surface sprays where they might dwell or run, space/aerosol sprays to eradicate an existing population if it is more confined. The best form of control is to remove the food source if possible.